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-rw-r--r--synapse/__init__.py2
-rw-r--r--synapse/api/errors.py3
-rw-r--r--synapse/api/room_versions.py5
-rw-r--r--synapse/app/_base.py4
-rw-r--r--synapse/config/appservice.py5
-rw-r--r--synapse/config/consent_config.py4
-rw-r--r--synapse/config/password_auth_providers.py4
-rw-r--r--synapse/config/repository.py5
-rw-r--r--synapse/config/server.py12
-rw-r--r--synapse/config/server_notices_config.py4
-rw-r--r--synapse/federation/federation_server.py13
-rw-r--r--synapse/federation/sender/__init__.py11
-rw-r--r--synapse/federation/transport/server.py8
-rw-r--r--synapse/handlers/deactivate_account.py37
-rw-r--r--synapse/handlers/federation.py9
-rw-r--r--synapse/handlers/register.py10
-rw-r--r--synapse/handlers/room_list.py341
-rw-r--r--synapse/handlers/room_member.py4
-rw-r--r--synapse/handlers/stats.py1
-rw-r--r--synapse/http/__init__.py6
-rw-r--r--synapse/http/client.py12
-rw-r--r--synapse/logging/opentracing.py9
-rw-r--r--synapse/logging/utils.py20
-rw-r--r--synapse/metrics/__init__.py4
-rw-r--r--synapse/metrics/_exposition.py4
-rw-r--r--synapse/python_dependencies.py17
-rw-r--r--synapse/rest/client/v1/room.py8
-rw-r--r--synapse/rest/media/v1/_base.py2
-rw-r--r--synapse/rest/media/v1/thumbnailer.py14
-rw-r--r--synapse/rest/media/v1/upload_resource.py8
-rw-r--r--synapse/state/__init__.py24
-rw-r--r--synapse/storage/client_ips.py175
-rw-r--r--synapse/storage/deviceinbox.py37
-rw-r--r--synapse/storage/devices.py49
-rw-r--r--synapse/storage/engines/postgres.py7
-rw-r--r--synapse/storage/engines/sqlite.py8
-rw-r--r--synapse/storage/events.py53
-rw-r--r--synapse/storage/events_bg_updates.py61
-rw-r--r--synapse/storage/events_worker.py14
-rw-r--r--synapse/storage/media_repository.py13
-rw-r--r--synapse/storage/push_rule.py16
-rw-r--r--synapse/storage/registration.py122
-rw-r--r--synapse/storage/room.py246
-rw-r--r--synapse/storage/roommember.py307
-rw-r--r--synapse/storage/schema/delta/56/destinations_retry_interval_type.sql.postgres18
-rw-r--r--synapse/storage/schema/delta/56/drop_unused_event_tables.sql20
-rw-r--r--synapse/storage/schema/delta/56/public_room_list_idx.sql16
-rw-r--r--synapse/storage/schema/delta/56/redaction_censor2.sql20
-rw-r--r--synapse/storage/schema/delta/56/redaction_censor3_fix_update.sql.postgres26
-rw-r--r--synapse/storage/schema/delta/56/unique_user_filter_index.py46
-rw-r--r--synapse/storage/search.py55
-rw-r--r--synapse/storage/state.py396
-rw-r--r--synapse/storage/stats.py3
-rw-r--r--synapse/storage/user_directory.py178
-rw-r--r--synapse/types.py3
-rw-r--r--synapse/util/async_helpers.py10
-rw-r--r--synapse/util/caches/__init__.py3
-rw-r--r--synapse/util/caches/descriptors.py22
-rw-r--r--synapse/util/caches/treecache.py4
-rw-r--r--synapse/util/metrics.py6
-rw-r--r--synapse/util/module_loader.py2
-rw-r--r--synapse/util/retryutils.py2
62 files changed, 1507 insertions, 1041 deletions
diff --git a/synapse/__init__.py b/synapse/__init__.py
index 4401fd52f0..1055f54e00 100644
--- a/synapse/__init__.py
+++ b/synapse/__init__.py
@@ -38,7 +38,7 @@ try:
 except ImportError:
     pass
 
-__version__ = "1.4.0rc1"
+__version__ = "1.4.0"
 
 if bool(os.environ.get("SYNAPSE_TEST_PATCH_LOG_CONTEXTS", False)):
     do_patch()
diff --git a/synapse/api/errors.py b/synapse/api/errors.py
index cf1ebf1af2..1bb2e86789 100644
--- a/synapse/api/errors.py
+++ b/synapse/api/errors.py
@@ -17,6 +17,7 @@
 """Contains exceptions and error codes."""
 
 import logging
+from typing import Dict
 
 from six import iteritems
 from six.moves import http_client
@@ -111,7 +112,7 @@ class ProxiedRequestError(SynapseError):
     def __init__(self, code, msg, errcode=Codes.UNKNOWN, additional_fields=None):
         super(ProxiedRequestError, self).__init__(code, msg, errcode)
         if additional_fields is None:
-            self._additional_fields = {}
+            self._additional_fields = {}  # type: Dict
         else:
             self._additional_fields = dict(additional_fields)
 
diff --git a/synapse/api/room_versions.py b/synapse/api/room_versions.py
index 95292b7dec..c6f50fd7b9 100644
--- a/synapse/api/room_versions.py
+++ b/synapse/api/room_versions.py
@@ -12,6 +12,9 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+
+from typing import Dict
+
 import attr
 
 
@@ -102,4 +105,4 @@ KNOWN_ROOM_VERSIONS = {
         RoomVersions.V4,
         RoomVersions.V5,
     )
-}  # type: dict[str, RoomVersion]
+}  # type: Dict[str, RoomVersion]
diff --git a/synapse/app/_base.py b/synapse/app/_base.py
index c30fdeee9a..2ac7d5c064 100644
--- a/synapse/app/_base.py
+++ b/synapse/app/_base.py
@@ -263,7 +263,9 @@ def start(hs, listeners=None):
         refresh_certificate(hs)
 
         # Start the tracer
-        synapse.logging.opentracing.init_tracer(hs.config)
+        synapse.logging.opentracing.init_tracer(  # type: ignore[attr-defined] # noqa
+            hs.config
+        )
 
         # It is now safe to start your Synapse.
         hs.start_listening(listeners)
diff --git a/synapse/config/appservice.py b/synapse/config/appservice.py
index 8387ff6805..28d36b1bc3 100644
--- a/synapse/config/appservice.py
+++ b/synapse/config/appservice.py
@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import logging
+from typing import Dict
 
 from six import string_types
 from six.moves.urllib import parse as urlparse
@@ -56,8 +57,8 @@ def load_appservices(hostname, config_files):
         return []
 
     # Dicts of value -> filename
-    seen_as_tokens = {}
-    seen_ids = {}
+    seen_as_tokens = {}  # type: Dict[str, str]
+    seen_ids = {}  # type: Dict[str, str]
 
     appservices = []
 
diff --git a/synapse/config/consent_config.py b/synapse/config/consent_config.py
index 94916f3a49..48976e17b1 100644
--- a/synapse/config/consent_config.py
+++ b/synapse/config/consent_config.py
@@ -73,8 +73,8 @@ DEFAULT_CONFIG = """\
 
 
 class ConsentConfig(Config):
-    def __init__(self):
-        super(ConsentConfig, self).__init__()
+    def __init__(self, *args):
+        super(ConsentConfig, self).__init__(*args)
 
         self.user_consent_version = None
         self.user_consent_template_dir = None
diff --git a/synapse/config/password_auth_providers.py b/synapse/config/password_auth_providers.py
index 788c39c9fb..c50e244394 100644
--- a/synapse/config/password_auth_providers.py
+++ b/synapse/config/password_auth_providers.py
@@ -13,6 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from typing import Any, List
+
 from synapse.util.module_loader import load_module
 
 from ._base import Config
@@ -22,7 +24,7 @@ LDAP_PROVIDER = "ldap_auth_provider.LdapAuthProvider"
 
 class PasswordAuthProviderConfig(Config):
     def read_config(self, config, **kwargs):
-        self.password_providers = []
+        self.password_providers = []  # type: List[Any]
         providers = []
 
         # We want to be backwards compatible with the old `ldap_config`
diff --git a/synapse/config/repository.py b/synapse/config/repository.py
index 52e014608a..14740891f3 100644
--- a/synapse/config/repository.py
+++ b/synapse/config/repository.py
@@ -15,6 +15,7 @@
 
 import os
 from collections import namedtuple
+from typing import Dict, List
 
 from synapse.python_dependencies import DependencyException, check_requirements
 from synapse.util.module_loader import load_module
@@ -61,7 +62,7 @@ def parse_thumbnail_requirements(thumbnail_sizes):
         Dictionary mapping from media type string to list of
         ThumbnailRequirement tuples.
     """
-    requirements = {}
+    requirements = {}  # type: Dict[str, List]
     for size in thumbnail_sizes:
         width = size["width"]
         height = size["height"]
@@ -130,7 +131,7 @@ class ContentRepositoryConfig(Config):
         #
         # We don't create the storage providers here as not all workers need
         # them to be started.
-        self.media_storage_providers = []
+        self.media_storage_providers = []  # type: List[tuple]
 
         for provider_config in storage_providers:
             # We special case the module "file_system" so as not to need to
diff --git a/synapse/config/server.py b/synapse/config/server.py
index 5ad7ee911d..709bd387e5 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -19,6 +19,7 @@ import logging
 import os.path
 import re
 from textwrap import indent
+from typing import List
 
 import attr
 import yaml
@@ -243,7 +244,7 @@ class ServerConfig(Config):
         # events with profile information that differ from the target's global profile.
         self.allow_per_room_profiles = config.get("allow_per_room_profiles", True)
 
-        self.listeners = []
+        self.listeners = []  # type: List[dict]
         for listener in config.get("listeners", []):
             if not isinstance(listener.get("port", None), int):
                 raise ConfigError(
@@ -287,7 +288,10 @@ class ServerConfig(Config):
                 validator=attr.validators.instance_of(bool), default=False
             )
             complexity = attr.ib(
-                validator=attr.validators.instance_of((int, float)), default=1.0
+                validator=attr.validators.instance_of(
+                    (float, int)  # type: ignore[arg-type] # noqa
+                ),
+                default=1.0,
             )
             complexity_error = attr.ib(
                 validator=attr.validators.instance_of(str),
@@ -366,7 +370,7 @@ class ServerConfig(Config):
             "cleanup_extremities_with_dummy_events", True
         )
 
-    def has_tls_listener(self):
+    def has_tls_listener(self) -> bool:
         return any(l["tls"] for l in self.listeners)
 
     def generate_config_section(
@@ -742,7 +746,7 @@ class ServerConfig(Config):
         #
         # Defaults to `7d`. Set to `null` to disable.
         #
-        redaction_retention_period: 7d
+        #redaction_retention_period: 28d
 
         # How long to track users' last seen time and IPs in the database.
         #
diff --git a/synapse/config/server_notices_config.py b/synapse/config/server_notices_config.py
index eaac3d73bc..6d4285ef93 100644
--- a/synapse/config/server_notices_config.py
+++ b/synapse/config/server_notices_config.py
@@ -59,8 +59,8 @@ class ServerNoticesConfig(Config):
             None if server notices are not enabled.
     """
 
-    def __init__(self):
-        super(ServerNoticesConfig, self).__init__()
+    def __init__(self, *args):
+        super(ServerNoticesConfig, self).__init__(*args)
         self.server_notices_mxid = None
         self.server_notices_mxid_display_name = None
         self.server_notices_mxid_avatar_url = None
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index da06ab379d..21e52c9695 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -36,7 +36,6 @@ from synapse.api.errors import (
     UnsupportedRoomVersionError,
 )
 from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
-from synapse.crypto.event_signing import compute_event_signature
 from synapse.events import room_version_to_event_format
 from synapse.federation.federation_base import FederationBase, event_from_pdu_json
 from synapse.federation.persistence import TransactionActions
@@ -322,18 +321,6 @@ class FederationServer(FederationBase):
         pdus = yield self.handler.get_state_for_pdu(room_id, event_id)
         auth_chain = yield self.store.get_auth_chain([pdu.event_id for pdu in pdus])
 
-        for event in auth_chain:
-            # We sign these again because there was a bug where we
-            # incorrectly signed things the first time round
-            if self.hs.is_mine_id(event.event_id):
-                event.signatures.update(
-                    compute_event_signature(
-                        event.get_pdu_json(),
-                        self.hs.hostname,
-                        self.hs.config.signing_key[0],
-                    )
-                )
-
         return {
             "pdus": [pdu.get_pdu_json() for pdu in pdus],
             "auth_chain": [pdu.get_pdu_json() for pdu in auth_chain],
diff --git a/synapse/federation/sender/__init__.py b/synapse/federation/sender/__init__.py
index d46f4aaeb1..2b2ee8612a 100644
--- a/synapse/federation/sender/__init__.py
+++ b/synapse/federation/sender/__init__.py
@@ -38,7 +38,7 @@ from synapse.metrics import (
     events_processed_counter,
 )
 from synapse.metrics.background_process_metrics import run_as_background_process
-from synapse.util.metrics import measure_func
+from synapse.util.metrics import Measure, measure_func
 
 logger = logging.getLogger(__name__)
 
@@ -183,8 +183,8 @@ class FederationSender(object):
                         # Otherwise if the last member on a server in a room is
                         # banned then it won't receive the event because it won't
                         # be in the room after the ban.
-                        destinations = yield self.state.get_current_hosts_in_room(
-                            event.room_id, latest_event_ids=event.prev_event_ids()
+                        destinations = yield self.state.get_hosts_in_room_at_events(
+                            event.room_id, event_ids=event.prev_event_ids()
                         )
                     except Exception:
                         logger.exception(
@@ -207,8 +207,9 @@ class FederationSender(object):
 
                 @defer.inlineCallbacks
                 def handle_room_events(events):
-                    for event in events:
-                        yield handle_event(event)
+                    with Measure(self.clock, "handle_room_events"):
+                        for event in events:
+                            yield handle_event(event)
 
                 events_by_room = {}
                 for event in events:
diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
index 7f8a16e355..0f16f21c2d 100644
--- a/synapse/federation/transport/server.py
+++ b/synapse/federation/transport/server.py
@@ -765,6 +765,10 @@ class PublicRoomList(BaseFederationServlet):
         else:
             network_tuple = ThirdPartyInstanceID(None, None)
 
+        if limit == 0:
+            # zero is a special value which corresponds to no limit.
+            limit = None
+
         data = await maybeDeferred(
             self.handler.get_local_public_room_list,
             limit,
@@ -800,6 +804,10 @@ class PublicRoomList(BaseFederationServlet):
         if search_filter is None:
             logger.warning("Nonefilter")
 
+        if limit == 0:
+            # zero is a special value which corresponds to no limit.
+            limit = None
+
         data = await self.handler.get_local_public_room_list(
             limit=limit,
             since_token=since_token,
diff --git a/synapse/handlers/deactivate_account.py b/synapse/handlers/deactivate_account.py
index d83912c9a4..63267a0a4c 100644
--- a/synapse/handlers/deactivate_account.py
+++ b/synapse/handlers/deactivate_account.py
@@ -120,6 +120,10 @@ class DeactivateAccountHandler(BaseHandler):
         # parts users from rooms (if it isn't already running)
         self._start_user_parting()
 
+        # Reject all pending invites for the user, so that the user doesn't show up in the
+        # "invited" section of rooms' members list.
+        yield self._reject_pending_invites_for_user(user_id)
+
         # Remove all information on the user from the account_validity table.
         if self._account_validity_enabled:
             yield self.store.delete_account_validity_for_user(user_id)
@@ -129,6 +133,39 @@ class DeactivateAccountHandler(BaseHandler):
 
         return identity_server_supports_unbinding
 
+    @defer.inlineCallbacks
+    def _reject_pending_invites_for_user(self, user_id):
+        """Reject pending invites addressed to a given user ID.
+
+        Args:
+            user_id (str): The user ID to reject pending invites for.
+        """
+        user = UserID.from_string(user_id)
+        pending_invites = yield self.store.get_invited_rooms_for_user(user_id)
+
+        for room in pending_invites:
+            try:
+                yield self._room_member_handler.update_membership(
+                    create_requester(user),
+                    user,
+                    room.room_id,
+                    "leave",
+                    ratelimit=False,
+                    require_consent=False,
+                )
+                logger.info(
+                    "Rejected invite for deactivated user %r in room %r",
+                    user_id,
+                    room.room_id,
+                )
+            except Exception:
+                logger.exception(
+                    "Failed to reject invite for user %r in room %r:"
+                    " ignoring and continuing",
+                    user_id,
+                    room.room_id,
+                )
+
     def _start_user_parting(self):
         """
         Start the process that goes through the table of users
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index f72b81d419..50fc0fde2a 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -2570,7 +2570,7 @@ class FederationHandler(BaseHandler):
         )
 
         try:
-            self.auth.check_from_context(room_version, event, context)
+            yield self.auth.check_from_context(room_version, event, context)
         except AuthError as e:
             logger.warn("Denying third party invite %r because %s", event, e)
             raise e
@@ -2599,7 +2599,12 @@ class FederationHandler(BaseHandler):
                 original_invite_id, allow_none=True
             )
         if original_invite:
-            display_name = original_invite.content["display_name"]
+            # If the m.room.third_party_invite event's content is empty, it means the
+            # invite has been revoked. In this case, we don't have to raise an error here
+            # because the auth check will fail on the invite (because it's not able to
+            # fetch public keys from the m.room.third_party_invite event's content, which
+            # is empty).
+            display_name = original_invite.content.get("display_name")
             event_dict["content"]["third_party_invite"]["display_name"] = display_name
         else:
             logger.info(
diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index 06bd03b77c..53410f120b 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -217,10 +217,9 @@ class RegistrationHandler(BaseHandler):
 
         else:
             # autogen a sequential user ID
-            attempts = 0
             user = None
             while not user:
-                localpart = yield self._generate_user_id(attempts > 0)
+                localpart = yield self._generate_user_id()
                 user = UserID(localpart, self.hs.hostname)
                 user_id = user.to_string()
                 yield self.check_user_id_not_appservice_exclusive(user_id)
@@ -238,7 +237,6 @@ class RegistrationHandler(BaseHandler):
                     # if user id is taken, just generate another
                     user = None
                     user_id = None
-                    attempts += 1
 
         if not self.hs.config.user_consent_at_registration:
             yield self._auto_join_rooms(user_id)
@@ -379,10 +377,10 @@ class RegistrationHandler(BaseHandler):
                 )
 
     @defer.inlineCallbacks
-    def _generate_user_id(self, reseed=False):
-        if reseed or self._next_generated_user_id is None:
+    def _generate_user_id(self):
+        if self._next_generated_user_id is None:
             with (yield self._generate_user_id_linearizer.queue(())):
-                if reseed or self._next_generated_user_id is None:
+                if self._next_generated_user_id is None:
                     self._next_generated_user_id = (
                         yield self.store.find_next_generated_user_id_localpart()
                     )
diff --git a/synapse/handlers/room_list.py b/synapse/handlers/room_list.py
index a7e55f00e5..c615206df1 100644
--- a/synapse/handlers/room_list.py
+++ b/synapse/handlers/room_list.py
@@ -16,8 +16,7 @@
 import logging
 from collections import namedtuple
 
-from six import PY3, iteritems
-from six.moves import range
+from six import iteritems
 
 import msgpack
 from unpaddedbase64 import decode_base64, encode_base64
@@ -27,7 +26,6 @@ from twisted.internet import defer
 from synapse.api.constants import EventTypes, JoinRules
 from synapse.api.errors import Codes, HttpResponseException
 from synapse.types import ThirdPartyInstanceID
-from synapse.util.async_helpers import concurrently_execute
 from synapse.util.caches.descriptors import cachedInlineCallbacks
 from synapse.util.caches.response_cache import ResponseCache
 
@@ -37,7 +35,6 @@ logger = logging.getLogger(__name__)
 
 REMOTE_ROOM_LIST_POLL_INTERVAL = 60 * 1000
 
-
 # This is used to indicate we should only return rooms published to the main list.
 EMPTY_THIRD_PARTY_ID = ThirdPartyInstanceID(None, None)
 
@@ -72,6 +69,8 @@ class RoomListHandler(BaseHandler):
                 This can be (None, None) to indicate the main list, or a particular
                 appservice and network id to use an appservice specific one.
                 Setting to None returns all public rooms across all lists.
+            from_federation (bool): true iff the request comes from the federation
+                API
         """
         if not self.enable_room_list_search:
             return defer.succeed({"chunk": [], "total_room_count_estimate": 0})
@@ -89,16 +88,8 @@ class RoomListHandler(BaseHandler):
             # appservice specific lists.
             logger.info("Bypassing cache as search request.")
 
-            # XXX: Quick hack to stop room directory queries taking too long.
-            # Timeout request after 60s. Probably want a more fundamental
-            # solution at some point
-            timeout = self.clock.time() + 60
             return self._get_public_room_list(
-                limit,
-                since_token,
-                search_filter,
-                network_tuple=network_tuple,
-                timeout=timeout,
+                limit, since_token, search_filter, network_tuple=network_tuple
             )
 
         key = (limit, since_token, network_tuple)
@@ -119,7 +110,6 @@ class RoomListHandler(BaseHandler):
         search_filter=None,
         network_tuple=EMPTY_THIRD_PARTY_ID,
         from_federation=False,
-        timeout=None,
     ):
         """Generate a public room list.
         Args:
@@ -132,240 +122,116 @@ class RoomListHandler(BaseHandler):
                 Setting to None returns all public rooms across all lists.
             from_federation (bool): Whether this request originated from a
                 federating server or a client. Used for room filtering.
-            timeout (int|None): Amount of seconds to wait for a response before
-                timing out.
         """
-        if since_token and since_token != "END":
-            since_token = RoomListNextBatch.from_token(since_token)
-        else:
-            since_token = None
 
-        rooms_to_order_value = {}
-        rooms_to_num_joined = {}
+        # Pagination tokens work by storing the room ID sent in the last batch,
+        # plus the direction (forwards or backwards). Next batch tokens always
+        # go forwards, prev batch tokens always go backwards.
 
-        newly_visible = []
-        newly_unpublished = []
         if since_token:
-            stream_token = since_token.stream_ordering
-            current_public_id = yield self.store.get_current_public_room_stream_id()
-            public_room_stream_id = since_token.public_room_stream_id
-            newly_visible, newly_unpublished = yield self.store.get_public_room_changes(
-                public_room_stream_id, current_public_id, network_tuple=network_tuple
-            )
-        else:
-            stream_token = yield self.store.get_room_max_stream_ordering()
-            public_room_stream_id = yield self.store.get_current_public_room_stream_id()
-
-        room_ids = yield self.store.get_public_room_ids_at_stream_id(
-            public_room_stream_id, network_tuple=network_tuple
-        )
-
-        # We want to return rooms in a particular order: the number of joined
-        # users. We then arbitrarily use the room_id as a tie breaker.
-
-        @defer.inlineCallbacks
-        def get_order_for_room(room_id):
-            # Most of the rooms won't have changed between the since token and
-            # now (especially if the since token is "now"). So, we can ask what
-            # the current users are in a room (that will hit a cache) and then
-            # check if the room has changed since the since token. (We have to
-            # do it in that order to avoid races).
-            # If things have changed then fall back to getting the current state
-            # at the since token.
-            joined_users = yield self.store.get_users_in_room(room_id)
-            if self.store.has_room_changed_since(room_id, stream_token):
-                latest_event_ids = yield self.store.get_forward_extremeties_for_room(
-                    room_id, stream_token
-                )
-
-                if not latest_event_ids:
-                    return
+            batch_token = RoomListNextBatch.from_token(since_token)
 
-                joined_users = yield self.state_handler.get_current_users_in_room(
-                    room_id, latest_event_ids
-                )
-
-            num_joined_users = len(joined_users)
-            rooms_to_num_joined[room_id] = num_joined_users
+            bounds = (batch_token.last_joined_members, batch_token.last_room_id)
+            forwards = batch_token.direction_is_forward
+        else:
+            batch_token = None
+            bounds = None
 
-            if num_joined_users == 0:
-                return
+            forwards = True
 
-            # We want larger rooms to be first, hence negating num_joined_users
-            rooms_to_order_value[room_id] = (-num_joined_users, room_id)
+        # we request one more than wanted to see if there are more pages to come
+        probing_limit = limit + 1 if limit is not None else None
 
-        logger.info(
-            "Getting ordering for %i rooms since %s", len(room_ids), stream_token
+        results = yield self.store.get_largest_public_rooms(
+            network_tuple,
+            search_filter,
+            probing_limit,
+            bounds=bounds,
+            forwards=forwards,
+            ignore_non_federatable=from_federation,
         )
-        yield concurrently_execute(get_order_for_room, room_ids, 10)
 
-        sorted_entries = sorted(rooms_to_order_value.items(), key=lambda e: e[1])
-        sorted_rooms = [room_id for room_id, _ in sorted_entries]
+        def build_room_entry(room):
+            entry = {
+                "room_id": room["room_id"],
+                "name": room["name"],
+                "topic": room["topic"],
+                "canonical_alias": room["canonical_alias"],
+                "num_joined_members": room["joined_members"],
+                "avatar_url": room["avatar"],
+                "world_readable": room["history_visibility"] == "world_readable",
+                "guest_can_join": room["guest_access"] == "can_join",
+            }
 
-        # `sorted_rooms` should now be a list of all public room ids that is
-        # stable across pagination. Therefore, we can use indices into this
-        # list as our pagination tokens.
+            # Filter out Nones – rather omit the field altogether
+            return {k: v for k, v in entry.items() if v is not None}
 
-        # Filter out rooms that we don't want to return
-        rooms_to_scan = [
-            r
-            for r in sorted_rooms
-            if r not in newly_unpublished and rooms_to_num_joined[r] > 0
-        ]
+        results = [build_room_entry(r) for r in results]
 
-        total_room_count = len(rooms_to_scan)
+        response = {}
+        num_results = len(results)
+        if limit is not None:
+            more_to_come = num_results == probing_limit
 
-        if since_token:
-            # Filter out rooms we've already returned previously
-            # `since_token.current_limit` is the index of the last room we
-            # sent down, so we exclude it and everything before/after it.
-            if since_token.direction_is_forward:
-                rooms_to_scan = rooms_to_scan[since_token.current_limit + 1 :]
+            # Depending on direction we trim either the front or back.
+            if forwards:
+                results = results[:limit]
             else:
-                rooms_to_scan = rooms_to_scan[: since_token.current_limit]
-                rooms_to_scan.reverse()
-
-        logger.info("After sorting and filtering, %i rooms remain", len(rooms_to_scan))
-
-        # _append_room_entry_to_chunk will append to chunk but will stop if
-        # len(chunk) > limit
-        #
-        # Normally we will generate enough results on the first iteration here,
-        #  but if there is a search filter, _append_room_entry_to_chunk may
-        # filter some results out, in which case we loop again.
-        #
-        # We don't want to scan over the entire range either as that
-        # would potentially waste a lot of work.
-        #
-        # XXX if there is no limit, we may end up DoSing the server with
-        # calls to get_current_state_ids for every single room on the
-        # server. Surely we should cap this somehow?
-        #
-        if limit:
-            step = limit + 1
+                results = results[-limit:]
         else:
-            # step cannot be zero
-            step = len(rooms_to_scan) if len(rooms_to_scan) != 0 else 1
-
-        chunk = []
-        for i in range(0, len(rooms_to_scan), step):
-            if timeout and self.clock.time() > timeout:
-                raise Exception("Timed out searching room directory")
-
-            batch = rooms_to_scan[i : i + step]
-            logger.info("Processing %i rooms for result", len(batch))
-            yield concurrently_execute(
-                lambda r: self._append_room_entry_to_chunk(
-                    r,
-                    rooms_to_num_joined[r],
-                    chunk,
-                    limit,
-                    search_filter,
-                    from_federation=from_federation,
-                ),
-                batch,
-                5,
-            )
-            logger.info("Now %i rooms in result", len(chunk))
-            if len(chunk) >= limit + 1:
-                break
-
-        chunk.sort(key=lambda e: (-e["num_joined_members"], e["room_id"]))
-
-        # Work out the new limit of the batch for pagination, or None if we
-        # know there are no more results that would be returned.
-        # i.e., [since_token.current_limit..new_limit] is the batch of rooms
-        # we've returned (or the reverse if we paginated backwards)
-        # We tried to pull out limit + 1 rooms above, so if we have <= limit
-        # then we know there are no more results to return
-        new_limit = None
-        if chunk and (not limit or len(chunk) > limit):
-
-            if not since_token or since_token.direction_is_forward:
-                if limit:
-                    chunk = chunk[:limit]
-                last_room_id = chunk[-1]["room_id"]
+            more_to_come = False
+
+        if num_results > 0:
+            final_entry = results[-1]
+            initial_entry = results[0]
+
+            if forwards:
+                if batch_token:
+                    # If there was a token given then we assume that there
+                    # must be previous results.
+                    response["prev_batch"] = RoomListNextBatch(
+                        last_joined_members=initial_entry["num_joined_members"],
+                        last_room_id=initial_entry["room_id"],
+                        direction_is_forward=False,
+                    ).to_token()
+
+                if more_to_come:
+                    response["next_batch"] = RoomListNextBatch(
+                        last_joined_members=final_entry["num_joined_members"],
+                        last_room_id=final_entry["room_id"],
+                        direction_is_forward=True,
+                    ).to_token()
             else:
-                if limit:
-                    chunk = chunk[-limit:]
-                last_room_id = chunk[0]["room_id"]
-
-            new_limit = sorted_rooms.index(last_room_id)
-
-        results = {"chunk": chunk, "total_room_count_estimate": total_room_count}
-
-        if since_token:
-            results["new_rooms"] = bool(newly_visible)
-
-        if not since_token or since_token.direction_is_forward:
-            if new_limit is not None:
-                results["next_batch"] = RoomListNextBatch(
-                    stream_ordering=stream_token,
-                    public_room_stream_id=public_room_stream_id,
-                    current_limit=new_limit,
-                    direction_is_forward=True,
-                ).to_token()
-
-            if since_token:
-                results["prev_batch"] = since_token.copy_and_replace(
-                    direction_is_forward=False,
-                    current_limit=since_token.current_limit + 1,
-                ).to_token()
-        else:
-            if new_limit is not None:
-                results["prev_batch"] = RoomListNextBatch(
-                    stream_ordering=stream_token,
-                    public_room_stream_id=public_room_stream_id,
-                    current_limit=new_limit,
-                    direction_is_forward=False,
-                ).to_token()
-
-            if since_token:
-                results["next_batch"] = since_token.copy_and_replace(
-                    direction_is_forward=True,
-                    current_limit=since_token.current_limit - 1,
-                ).to_token()
-
-        return results
-
-    @defer.inlineCallbacks
-    def _append_room_entry_to_chunk(
-        self,
-        room_id,
-        num_joined_users,
-        chunk,
-        limit,
-        search_filter,
-        from_federation=False,
-    ):
-        """Generate the entry for a room in the public room list and append it
-        to the `chunk` if it matches the search filter
-
-        Args:
-            room_id (str): The ID of the room.
-            num_joined_users (int): The number of joined users in the room.
-            chunk (list)
-            limit (int|None): Maximum amount of rooms to display. Function will
-                return if length of chunk is greater than limit + 1.
-            search_filter (dict|None)
-            from_federation (bool): Whether this request originated from a
-                federating server or a client. Used for room filtering.
-        """
-        if limit and len(chunk) > limit + 1:
-            # We've already got enough, so lets just drop it.
-            return
+                if batch_token:
+                    response["next_batch"] = RoomListNextBatch(
+                        last_joined_members=final_entry["num_joined_members"],
+                        last_room_id=final_entry["room_id"],
+                        direction_is_forward=True,
+                    ).to_token()
+
+                if more_to_come:
+                    response["prev_batch"] = RoomListNextBatch(
+                        last_joined_members=initial_entry["num_joined_members"],
+                        last_room_id=initial_entry["room_id"],
+                        direction_is_forward=False,
+                    ).to_token()
+
+        for room in results:
+            # populate search result entries with additional fields, namely
+            # 'aliases'
+            room_id = room["room_id"]
+
+            aliases = yield self.store.get_aliases_for_room(room_id)
+            if aliases:
+                room["aliases"] = aliases
 
-        result = yield self.generate_room_entry(room_id, num_joined_users)
-        if not result:
-            return
+        response["chunk"] = results
 
-        if from_federation and not result.get("m.federate", True):
-            # This is a room that other servers cannot join. Do not show them
-            # this room.
-            return
+        response["total_room_count_estimate"] = yield self.store.count_public_rooms(
+            network_tuple, ignore_non_federatable=from_federation
+        )
 
-        if _matches_room_entry(result, search_filter):
-            chunk.append(result)
+        return response
 
     @cachedInlineCallbacks(num_args=1, cache_context=True)
     def generate_room_entry(
@@ -580,18 +446,15 @@ class RoomListNextBatch(
     namedtuple(
         "RoomListNextBatch",
         (
-            "stream_ordering",  # stream_ordering of the first public room list
-            "public_room_stream_id",  # public room stream id for first public room list
-            "current_limit",  # The number of previous rooms returned
+            "last_joined_members",  # The count to get rooms after/before
+            "last_room_id",  # The room_id to get rooms after/before
             "direction_is_forward",  # Bool if this is a next_batch, false if prev_batch
         ),
     )
 ):
-
     KEY_DICT = {
-        "stream_ordering": "s",
-        "public_room_stream_id": "p",
-        "current_limit": "n",
+        "last_joined_members": "m",
+        "last_room_id": "r",
         "direction_is_forward": "d",
     }
 
@@ -599,13 +462,7 @@ class RoomListNextBatch(
 
     @classmethod
     def from_token(cls, token):
-        if PY3:
-            # The argument raw=False is only available on new versions of
-            # msgpack, and only really needed on Python 3. Gate it behind
-            # a PY3 check to avoid causing issues on Debian-packaged versions.
-            decoded = msgpack.loads(decode_base64(token), raw=False)
-        else:
-            decoded = msgpack.loads(decode_base64(token))
+        decoded = msgpack.loads(decode_base64(token), raw=False)
         return RoomListNextBatch(
             **{cls.REVERSE_KEY_DICT[key]: val for key, val in decoded.items()}
         )
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index 19e44b5460..1edc657f8a 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -216,8 +216,8 @@ class RoomMemberHandler(object):
                 yield self.copy_room_tags_and_direct_to_room(
                     predecessor["room_id"], room_id, user_id
                 )
-                # Move over old push rules
-                yield self.store.move_push_rules_from_room_to_room_for_user(
+                # Copy over push rules
+                yield self.store.copy_push_rules_from_room_to_room_for_user(
                     predecessor["room_id"], room_id, user_id
                 )
         elif event.membership == Membership.LEAVE:
diff --git a/synapse/handlers/stats.py b/synapse/handlers/stats.py
index cbac7c347a..c62b113115 100644
--- a/synapse/handlers/stats.py
+++ b/synapse/handlers/stats.py
@@ -293,6 +293,7 @@ class StatsHandler(StateDeltasHandler):
                 room_state["guest_access"] = event_content.get("guest_access")
 
         for room_id, state in room_to_state_updates.items():
+            logger.info("Updating room_stats_state for %s: %s", room_id, state)
             yield self.store.update_room_state(room_id, state)
 
         return room_to_stats_deltas, user_to_stats_deltas
diff --git a/synapse/http/__init__.py b/synapse/http/__init__.py
index 3acf772cd1..3880ce0d94 100644
--- a/synapse/http/__init__.py
+++ b/synapse/http/__init__.py
@@ -42,11 +42,13 @@ def cancelled_to_request_timed_out_error(value, timeout):
 
 
 ACCESS_TOKEN_RE = re.compile(r"(\?.*access(_|%5[Ff])token=)[^&]*(.*)$")
+CLIENT_SECRET_RE = re.compile(r"(\?.*client(_|%5[Ff])secret=)[^&]*(.*)$")
 
 
 def redact_uri(uri):
-    """Strips access tokens from the uri replaces with <redacted>"""
-    return ACCESS_TOKEN_RE.sub(r"\1<redacted>\3", uri)
+    """Strips sensitive information from the uri replaces with <redacted>"""
+    uri = ACCESS_TOKEN_RE.sub(r"\1<redacted>\3", uri)
+    return CLIENT_SECRET_RE.sub(r"\1<redacted>\3", uri)
 
 
 class QuieterFileBodyProducer(FileBodyProducer):
diff --git a/synapse/http/client.py b/synapse/http/client.py
index 51765ae3c0..cdf828a4ff 100644
--- a/synapse/http/client.py
+++ b/synapse/http/client.py
@@ -327,7 +327,7 @@ class SimpleHttpClient(object):
         Args:
             uri (str):
             args (dict[str, str|List[str]]): query params
-            headers (dict[str, List[str]]|None): If not None, a map from
+            headers (dict[str|bytes, List[str|bytes]]|None): If not None, a map from
                header name to a list of values for that header
 
         Returns:
@@ -371,7 +371,7 @@ class SimpleHttpClient(object):
         Args:
             uri (str):
             post_json (object):
-            headers (dict[str, List[str]]|None): If not None, a map from
+            headers (dict[str|bytes, List[str|bytes]]|None): If not None, a map from
                header name to a list of values for that header
 
         Returns:
@@ -414,7 +414,7 @@ class SimpleHttpClient(object):
                 None.
                 **Note**: The value of each key is assumed to be an iterable
                 and *not* a string.
-            headers (dict[str, List[str]]|None): If not None, a map from
+            headers (dict[str|bytes, List[str|bytes]]|None): If not None, a map from
                header name to a list of values for that header
         Returns:
             Deferred: Succeeds when we get *any* 2xx HTTP response, with the
@@ -438,7 +438,7 @@ class SimpleHttpClient(object):
                 None.
                 **Note**: The value of each key is assumed to be an iterable
                 and *not* a string.
-            headers (dict[str, List[str]]|None): If not None, a map from
+            headers (dict[str|bytes, List[str|bytes]]|None): If not None, a map from
                header name to a list of values for that header
         Returns:
             Deferred: Succeeds when we get *any* 2xx HTTP response, with the
@@ -482,7 +482,7 @@ class SimpleHttpClient(object):
                 None.
                 **Note**: The value of each key is assumed to be an iterable
                 and *not* a string.
-            headers (dict[str, List[str]]|None): If not None, a map from
+            headers (dict[str|bytes, List[str|bytes]]|None): If not None, a map from
                header name to a list of values for that header
         Returns:
             Deferred: Succeeds when we get *any* 2xx HTTP response, with the
@@ -516,7 +516,7 @@ class SimpleHttpClient(object):
         Args:
             url (str): The URL to GET
             output_stream (file): File to write the response body to.
-            headers (dict[str, List[str]]|None): If not None, a map from
+            headers (dict[str|bytes, List[str|bytes]]|None): If not None, a map from
                header name to a list of values for that header
         Returns:
             A (int,dict,string,int) tuple of the file length, dict of the response
diff --git a/synapse/logging/opentracing.py b/synapse/logging/opentracing.py
index 308a27213b..cd1ff6a518 100644
--- a/synapse/logging/opentracing.py
+++ b/synapse/logging/opentracing.py
@@ -170,6 +170,7 @@ import inspect
 import logging
 import re
 from functools import wraps
+from typing import Dict
 
 from canonicaljson import json
 
@@ -547,7 +548,7 @@ def inject_active_span_twisted_headers(headers, destination, check_destination=T
         return
 
     span = opentracing.tracer.active_span
-    carrier = {}
+    carrier = {}  # type: Dict[str, str]
     opentracing.tracer.inject(span, opentracing.Format.HTTP_HEADERS, carrier)
 
     for key, value in carrier.items():
@@ -584,7 +585,7 @@ def inject_active_span_byte_dict(headers, destination, check_destination=True):
 
     span = opentracing.tracer.active_span
 
-    carrier = {}
+    carrier = {}  # type: Dict[str, str]
     opentracing.tracer.inject(span, opentracing.Format.HTTP_HEADERS, carrier)
 
     for key, value in carrier.items():
@@ -639,7 +640,7 @@ def get_active_span_text_map(destination=None):
     if destination and not whitelisted_homeserver(destination):
         return {}
 
-    carrier = {}
+    carrier = {}  # type: Dict[str, str]
     opentracing.tracer.inject(
         opentracing.tracer.active_span, opentracing.Format.TEXT_MAP, carrier
     )
@@ -653,7 +654,7 @@ def active_span_context_as_string():
     Returns:
         The active span context encoded as a string.
     """
-    carrier = {}
+    carrier = {}  # type: Dict[str, str]
     if opentracing:
         opentracing.tracer.inject(
             opentracing.tracer.active_span, opentracing.Format.TEXT_MAP, carrier
diff --git a/synapse/logging/utils.py b/synapse/logging/utils.py
index 7df0fa6087..6073fc2725 100644
--- a/synapse/logging/utils.py
+++ b/synapse/logging/utils.py
@@ -119,7 +119,11 @@ def trace_function(f):
         logger = logging.getLogger(name)
         level = logging.DEBUG
 
-        s = inspect.currentframe().f_back
+        frame = inspect.currentframe()
+        if frame is None:
+            raise Exception("Can't get current frame!")
+
+        s = frame.f_back
 
         to_print = [
             "\t%s:%s %s. Args: args=%s, kwargs=%s"
@@ -144,7 +148,7 @@ def trace_function(f):
             pathname=pathname,
             lineno=lineno,
             msg=msg,
-            args=None,
+            args=tuple(),
             exc_info=None,
         )
 
@@ -157,7 +161,12 @@ def trace_function(f):
 
 
 def get_previous_frames():
-    s = inspect.currentframe().f_back.f_back
+
+    frame = inspect.currentframe()
+    if frame is None:
+        raise Exception("Can't get current frame!")
+
+    s = frame.f_back.f_back
     to_return = []
     while s:
         if s.f_globals["__name__"].startswith("synapse"):
@@ -174,7 +183,10 @@ def get_previous_frames():
 
 
 def get_previous_frame(ignore=[]):
-    s = inspect.currentframe().f_back.f_back
+    frame = inspect.currentframe()
+    if frame is None:
+        raise Exception("Can't get current frame!")
+    s = frame.f_back.f_back
 
     while s:
         if s.f_globals["__name__"].startswith("synapse"):
diff --git a/synapse/metrics/__init__.py b/synapse/metrics/__init__.py
index bec3b13397..0b45e1f52a 100644
--- a/synapse/metrics/__init__.py
+++ b/synapse/metrics/__init__.py
@@ -125,7 +125,7 @@ class InFlightGauge(object):
         )
 
         # Counts number of in flight blocks for a given set of label values
-        self._registrations = {}
+        self._registrations = {}  # type: Dict
 
         # Protects access to _registrations
         self._lock = threading.Lock()
@@ -226,7 +226,7 @@ class BucketCollector(object):
         # Fetch the data -- this must be synchronous!
         data = self.data_collector()
 
-        buckets = {}
+        buckets = {}  # type: Dict[float, int]
 
         res = []
         for x in data.keys():
diff --git a/synapse/metrics/_exposition.py b/synapse/metrics/_exposition.py
index 74d9c3ecd3..a248103191 100644
--- a/synapse/metrics/_exposition.py
+++ b/synapse/metrics/_exposition.py
@@ -36,9 +36,9 @@ from twisted.web.resource import Resource
 try:
     from prometheus_client.samples import Sample
 except ImportError:
-    Sample = namedtuple(
+    Sample = namedtuple(  # type: ignore[no-redef] # noqa
         "Sample", ["name", "labels", "value", "timestamp", "exemplar"]
-    )  # type: ignore
+    )
 
 
 CONTENT_TYPE_LATEST = str("text/plain; version=0.0.4; charset=utf-8")
diff --git a/synapse/python_dependencies.py b/synapse/python_dependencies.py
index 0bd563edc7..aa7da1c543 100644
--- a/synapse/python_dependencies.py
+++ b/synapse/python_dependencies.py
@@ -15,7 +15,7 @@
 # limitations under the License.
 
 import logging
-from typing import Set
+from typing import List, Set
 
 from pkg_resources import (
     DistributionNotFound,
@@ -73,6 +73,7 @@ REQUIREMENTS = [
     "netaddr>=0.7.18",
     "Jinja2>=2.9",
     "bleach>=1.4.3",
+    "typing-extensions>=3.7.4",
 ]
 
 CONDITIONAL_REQUIREMENTS = {
@@ -144,7 +145,11 @@ def check_requirements(for_feature=None):
             deps_needed.append(dependency)
             errors.append(
                 "Needed %s, got %s==%s"
-                % (dependency, e.dist.project_name, e.dist.version)
+                % (
+                    dependency,
+                    e.dist.project_name,  # type: ignore[attr-defined] # noqa
+                    e.dist.version,  # type: ignore[attr-defined] # noqa
+                )
             )
         except DistributionNotFound:
             deps_needed.append(dependency)
@@ -159,7 +164,7 @@ def check_requirements(for_feature=None):
     if not for_feature:
         # Check the optional dependencies are up to date. We allow them to not be
         # installed.
-        OPTS = sum(CONDITIONAL_REQUIREMENTS.values(), [])
+        OPTS = sum(CONDITIONAL_REQUIREMENTS.values(), [])  # type: List[str]
 
         for dependency in OPTS:
             try:
@@ -168,7 +173,11 @@ def check_requirements(for_feature=None):
                 deps_needed.append(dependency)
                 errors.append(
                     "Needed optional %s, got %s==%s"
-                    % (dependency, e.dist.project_name, e.dist.version)
+                    % (
+                        dependency,
+                        e.dist.project_name,  # type: ignore[attr-defined] # noqa
+                        e.dist.version,  # type: ignore[attr-defined] # noqa
+                    )
                 )
             except DistributionNotFound:
                 # If it's not found, we don't care
diff --git a/synapse/rest/client/v1/room.py b/synapse/rest/client/v1/room.py
index 6bf924dedc..9c1d41421c 100644
--- a/synapse/rest/client/v1/room.py
+++ b/synapse/rest/client/v1/room.py
@@ -361,6 +361,10 @@ class PublicRoomListRestServlet(TransactionRestServlet):
         limit = parse_integer(request, "limit", 0)
         since_token = parse_string(request, "since", None)
 
+        if limit == 0:
+            # zero is a special value which corresponds to no limit.
+            limit = None
+
         handler = self.hs.get_room_list_handler()
         if server:
             data = yield handler.get_remote_public_room_list(
@@ -398,6 +402,10 @@ class PublicRoomListRestServlet(TransactionRestServlet):
         else:
             network_tuple = ThirdPartyInstanceID.from_string(third_party_instance_id)
 
+        if limit == 0:
+            # zero is a special value which corresponds to no limit.
+            limit = None
+
         handler = self.hs.get_room_list_handler()
         if server:
             data = yield handler.get_remote_public_room_list(
diff --git a/synapse/rest/media/v1/_base.py b/synapse/rest/media/v1/_base.py
index 5fefee4dde..65bbf00073 100644
--- a/synapse/rest/media/v1/_base.py
+++ b/synapse/rest/media/v1/_base.py
@@ -195,7 +195,7 @@ def respond_with_responder(request, responder, media_type, file_size, upload_nam
         respond_404(request)
         return
 
-    logger.debug("Responding to media request with responder %s")
+    logger.debug("Responding to media request with responder %s", responder)
     add_file_headers(request, media_type, file_size, upload_name)
     try:
         with responder:
diff --git a/synapse/rest/media/v1/thumbnailer.py b/synapse/rest/media/v1/thumbnailer.py
index c995d7e043..8cf415e29d 100644
--- a/synapse/rest/media/v1/thumbnailer.py
+++ b/synapse/rest/media/v1/thumbnailer.py
@@ -82,13 +82,21 @@ class Thumbnailer(object):
         else:
             return (max_height * self.width) // self.height, max_height
 
+    def _resize(self, width, height):
+        # 1-bit or 8-bit color palette images need converting to RGB
+        # otherwise they will be scaled using nearest neighbour which
+        # looks awful
+        if self.image.mode in ["1", "P"]:
+            self.image = self.image.convert("RGB")
+        return self.image.resize((width, height), Image.ANTIALIAS)
+
     def scale(self, width, height, output_type):
         """Rescales the image to the given dimensions.
 
         Returns:
             BytesIO: the bytes of the encoded image ready to be written to disk
         """
-        scaled = self.image.resize((width, height), Image.ANTIALIAS)
+        scaled = self._resize(width, height)
         return self._encode_image(scaled, output_type)
 
     def crop(self, width, height, output_type):
@@ -107,13 +115,13 @@ class Thumbnailer(object):
         """
         if width * self.height > height * self.width:
             scaled_height = (width * self.height) // self.width
-            scaled_image = self.image.resize((width, scaled_height), Image.ANTIALIAS)
+            scaled_image = self._resize(width, scaled_height)
             crop_top = (scaled_height - height) // 2
             crop_bottom = height + crop_top
             cropped = scaled_image.crop((0, crop_top, width, crop_bottom))
         else:
             scaled_width = (height * self.width) // self.height
-            scaled_image = self.image.resize((scaled_width, height), Image.ANTIALIAS)
+            scaled_image = self._resize(scaled_width, height)
             crop_left = (scaled_width - width) // 2
             crop_right = width + crop_left
             cropped = scaled_image.crop((crop_left, 0, crop_right, height))
diff --git a/synapse/rest/media/v1/upload_resource.py b/synapse/rest/media/v1/upload_resource.py
index 5d76bbdf68..83d005812d 100644
--- a/synapse/rest/media/v1/upload_resource.py
+++ b/synapse/rest/media/v1/upload_resource.py
@@ -17,7 +17,7 @@ import logging
 
 from twisted.web.server import NOT_DONE_YET
 
-from synapse.api.errors import SynapseError
+from synapse.api.errors import Codes, SynapseError
 from synapse.http.server import (
     DirectServeResource,
     respond_with_json,
@@ -56,7 +56,11 @@ class UploadResource(DirectServeResource):
         if content_length is None:
             raise SynapseError(msg="Request must specify a Content-Length", code=400)
         if int(content_length) > self.max_upload_size:
-            raise SynapseError(msg="Upload request body is too large", code=413)
+            raise SynapseError(
+                msg="Upload request body is too large",
+                code=413,
+                errcode=Codes.TOO_LARGE,
+            )
 
         upload_name = parse_string(request, b"filename", encoding=None)
         if upload_name:
diff --git a/synapse/state/__init__.py b/synapse/state/__init__.py
index 2b0f4c79ee..dc9f5a9008 100644
--- a/synapse/state/__init__.py
+++ b/synapse/state/__init__.py
@@ -33,7 +33,7 @@ from synapse.state import v1, v2
 from synapse.util.async_helpers import Linearizer
 from synapse.util.caches import get_cache_factor_for
 from synapse.util.caches.expiringcache import ExpiringCache
-from synapse.util.metrics import Measure
+from synapse.util.metrics import Measure, measure_func
 
 logger = logging.getLogger(__name__)
 
@@ -191,11 +191,22 @@ class StateHandler(object):
         return joined_users
 
     @defer.inlineCallbacks
-    def get_current_hosts_in_room(self, room_id, latest_event_ids=None):
-        if not latest_event_ids:
-            latest_event_ids = yield self.store.get_latest_event_ids_in_room(room_id)
-        logger.debug("calling resolve_state_groups from get_current_hosts_in_room")
-        entry = yield self.resolve_state_groups_for_events(room_id, latest_event_ids)
+    def get_current_hosts_in_room(self, room_id):
+        event_ids = yield self.store.get_latest_event_ids_in_room(room_id)
+        return (yield self.get_hosts_in_room_at_events(room_id, event_ids))
+
+    @defer.inlineCallbacks
+    def get_hosts_in_room_at_events(self, room_id, event_ids):
+        """Get the hosts that were in a room at the given event ids
+
+        Args:
+            room_id (str):
+            event_ids (list[str]):
+
+        Returns:
+            Deferred[list[str]]: the hosts in the room at the given events
+        """
+        entry = yield self.resolve_state_groups_for_events(room_id, event_ids)
         joined_hosts = yield self.store.get_joined_hosts(room_id, entry)
         return joined_hosts
 
@@ -344,6 +355,7 @@ class StateHandler(object):
 
         return context
 
+    @measure_func()
     @defer.inlineCallbacks
     def resolve_state_groups_for_events(self, room_id, event_ids):
         """ Given a list of event_ids this method fetches the state at each
diff --git a/synapse/storage/client_ips.py b/synapse/storage/client_ips.py
index 539584288d..067820a5da 100644
--- a/synapse/storage/client_ips.py
+++ b/synapse/storage/client_ips.py
@@ -33,16 +33,9 @@ logger = logging.getLogger(__name__)
 LAST_SEEN_GRANULARITY = 120 * 1000
 
 
-class ClientIpStore(background_updates.BackgroundUpdateStore):
+class ClientIpBackgroundUpdateStore(background_updates.BackgroundUpdateStore):
     def __init__(self, db_conn, hs):
-
-        self.client_ip_last_seen = Cache(
-            name="client_ip_last_seen", keylen=4, max_entries=50000 * CACHE_SIZE_FACTOR
-        )
-
-        super(ClientIpStore, self).__init__(db_conn, hs)
-
-        self.user_ips_max_age = hs.config.user_ips_max_age
+        super(ClientIpBackgroundUpdateStore, self).__init__(db_conn, hs)
 
         self.register_background_index_update(
             "user_ips_device_index",
@@ -92,19 +85,6 @@ class ClientIpStore(background_updates.BackgroundUpdateStore):
             "devices_last_seen", self._devices_last_seen_update
         )
 
-        # (user_id, access_token, ip,) -> (user_agent, device_id, last_seen)
-        self._batch_row_update = {}
-
-        self._client_ip_looper = self._clock.looping_call(
-            self._update_client_ips_batch, 5 * 1000
-        )
-        self.hs.get_reactor().addSystemEventTrigger(
-            "before", "shutdown", self._update_client_ips_batch
-        )
-
-        if self.user_ips_max_age:
-            self._clock.looping_call(self._prune_old_user_ips, 5 * 1000)
-
     @defer.inlineCallbacks
     def _remove_user_ip_nonunique(self, progress, batch_size):
         def f(conn):
@@ -304,6 +284,110 @@ class ClientIpStore(background_updates.BackgroundUpdateStore):
         return batch_size
 
     @defer.inlineCallbacks
+    def _devices_last_seen_update(self, progress, batch_size):
+        """Background update to insert last seen info into devices table
+        """
+
+        last_user_id = progress.get("last_user_id", "")
+        last_device_id = progress.get("last_device_id", "")
+
+        def _devices_last_seen_update_txn(txn):
+            # This consists of two queries:
+            #
+            #   1. The sub-query searches for the next N devices and joins
+            #      against user_ips to find the max last_seen associated with
+            #      that device.
+            #   2. The outer query then joins again against user_ips on
+            #      user/device/last_seen. This *should* hopefully only
+            #      return one row, but if it does return more than one then
+            #      we'll just end up updating the same device row multiple
+            #      times, which is fine.
+
+            if self.database_engine.supports_tuple_comparison:
+                where_clause = "(user_id, device_id) > (?, ?)"
+                where_args = [last_user_id, last_device_id]
+            else:
+                # We explicitly do a `user_id >= ? AND (...)` here to ensure
+                # that an index is used, as doing `user_id > ? OR (user_id = ? AND ...)`
+                # makes it hard for query optimiser to tell that it can use the
+                # index on user_id
+                where_clause = "user_id >= ? AND (user_id > ? OR device_id > ?)"
+                where_args = [last_user_id, last_user_id, last_device_id]
+
+            sql = """
+                SELECT
+                    last_seen, ip, user_agent, user_id, device_id
+                FROM (
+                    SELECT
+                        user_id, device_id, MAX(u.last_seen) AS last_seen
+                    FROM devices
+                    INNER JOIN user_ips AS u USING (user_id, device_id)
+                    WHERE %(where_clause)s
+                    GROUP BY user_id, device_id
+                    ORDER BY user_id ASC, device_id ASC
+                    LIMIT ?
+                ) c
+                INNER JOIN user_ips AS u USING (user_id, device_id, last_seen)
+            """ % {
+                "where_clause": where_clause
+            }
+            txn.execute(sql, where_args + [batch_size])
+
+            rows = txn.fetchall()
+            if not rows:
+                return 0
+
+            sql = """
+                UPDATE devices
+                SET last_seen = ?, ip = ?, user_agent = ?
+                WHERE user_id = ? AND device_id = ?
+            """
+            txn.execute_batch(sql, rows)
+
+            _, _, _, user_id, device_id = rows[-1]
+            self._background_update_progress_txn(
+                txn,
+                "devices_last_seen",
+                {"last_user_id": user_id, "last_device_id": device_id},
+            )
+
+            return len(rows)
+
+        updated = yield self.runInteraction(
+            "_devices_last_seen_update", _devices_last_seen_update_txn
+        )
+
+        if not updated:
+            yield self._end_background_update("devices_last_seen")
+
+        return updated
+
+
+class ClientIpStore(ClientIpBackgroundUpdateStore):
+    def __init__(self, db_conn, hs):
+
+        self.client_ip_last_seen = Cache(
+            name="client_ip_last_seen", keylen=4, max_entries=50000 * CACHE_SIZE_FACTOR
+        )
+
+        super(ClientIpStore, self).__init__(db_conn, hs)
+
+        self.user_ips_max_age = hs.config.user_ips_max_age
+
+        # (user_id, access_token, ip,) -> (user_agent, device_id, last_seen)
+        self._batch_row_update = {}
+
+        self._client_ip_looper = self._clock.looping_call(
+            self._update_client_ips_batch, 5 * 1000
+        )
+        self.hs.get_reactor().addSystemEventTrigger(
+            "before", "shutdown", self._update_client_ips_batch
+        )
+
+        if self.user_ips_max_age:
+            self._clock.looping_call(self._prune_old_user_ips, 5 * 1000)
+
+    @defer.inlineCallbacks
     def insert_client_ip(
         self, user_id, access_token, ip, user_agent, device_id, now=None
     ):
@@ -454,53 +538,6 @@ class ClientIpStore(background_updates.BackgroundUpdateStore):
             for (access_token, ip), (user_agent, last_seen) in iteritems(results)
         )
 
-    @defer.inlineCallbacks
-    def _devices_last_seen_update(self, progress, batch_size):
-        """Background update to insert last seen info into devices table
-        """
-
-        last_user_id = progress.get("last_user_id", "")
-        last_device_id = progress.get("last_device_id", "")
-
-        def _devices_last_seen_update_txn(txn):
-            sql = """
-                SELECT u.last_seen, u.ip, u.user_agent, user_id, device_id FROM devices
-                INNER JOIN user_ips AS u USING (user_id, device_id)
-                WHERE user_id > ? OR (user_id = ? AND device_id > ?)
-                ORDER BY user_id ASC, device_id ASC
-                LIMIT ?
-            """
-            txn.execute(sql, (last_user_id, last_user_id, last_device_id, batch_size))
-
-            rows = txn.fetchall()
-            if not rows:
-                return 0
-
-            sql = """
-                UPDATE devices
-                SET last_seen = ?, ip = ?, user_agent = ?
-                WHERE user_id = ? AND device_id = ?
-            """
-            txn.execute_batch(sql, rows)
-
-            _, _, _, user_id, device_id = rows[-1]
-            self._background_update_progress_txn(
-                txn,
-                "devices_last_seen",
-                {"last_user_id": user_id, "last_device_id": device_id},
-            )
-
-            return len(rows)
-
-        updated = yield self.runInteraction(
-            "_devices_last_seen_update", _devices_last_seen_update_txn
-        )
-
-        if not updated:
-            yield self._end_background_update("devices_last_seen")
-
-        return updated
-
     @wrap_as_background_process("prune_old_user_ips")
     async def _prune_old_user_ips(self):
         """Removes entries in user IPs older than the configured period.
diff --git a/synapse/storage/deviceinbox.py b/synapse/storage/deviceinbox.py
index 6b7458304e..70bc2bb2cc 100644
--- a/synapse/storage/deviceinbox.py
+++ b/synapse/storage/deviceinbox.py
@@ -208,11 +208,11 @@ class DeviceInboxWorkerStore(SQLBaseStore):
         )
 
 
-class DeviceInboxStore(DeviceInboxWorkerStore, BackgroundUpdateStore):
+class DeviceInboxBackgroundUpdateStore(BackgroundUpdateStore):
     DEVICE_INBOX_STREAM_ID = "device_inbox_stream_drop"
 
     def __init__(self, db_conn, hs):
-        super(DeviceInboxStore, self).__init__(db_conn, hs)
+        super(DeviceInboxBackgroundUpdateStore, self).__init__(db_conn, hs)
 
         self.register_background_index_update(
             "device_inbox_stream_index",
@@ -225,6 +225,26 @@ class DeviceInboxStore(DeviceInboxWorkerStore, BackgroundUpdateStore):
             self.DEVICE_INBOX_STREAM_ID, self._background_drop_index_device_inbox
         )
 
+    @defer.inlineCallbacks
+    def _background_drop_index_device_inbox(self, progress, batch_size):
+        def reindex_txn(conn):
+            txn = conn.cursor()
+            txn.execute("DROP INDEX IF EXISTS device_inbox_stream_id")
+            txn.close()
+
+        yield self.runWithConnection(reindex_txn)
+
+        yield self._end_background_update(self.DEVICE_INBOX_STREAM_ID)
+
+        return 1
+
+
+class DeviceInboxStore(DeviceInboxWorkerStore, DeviceInboxBackgroundUpdateStore):
+    DEVICE_INBOX_STREAM_ID = "device_inbox_stream_drop"
+
+    def __init__(self, db_conn, hs):
+        super(DeviceInboxStore, self).__init__(db_conn, hs)
+
         # Map of (user_id, device_id) to the last stream_id that has been
         # deleted up to. This is so that we can no op deletions.
         self._last_device_delete_cache = ExpiringCache(
@@ -435,16 +455,3 @@ class DeviceInboxStore(DeviceInboxWorkerStore, BackgroundUpdateStore):
         return self.runInteraction(
             "get_all_new_device_messages", get_all_new_device_messages_txn
         )
-
-    @defer.inlineCallbacks
-    def _background_drop_index_device_inbox(self, progress, batch_size):
-        def reindex_txn(conn):
-            txn = conn.cursor()
-            txn.execute("DROP INDEX IF EXISTS device_inbox_stream_id")
-            txn.close()
-
-        yield self.runWithConnection(reindex_txn)
-
-        yield self._end_background_update(self.DEVICE_INBOX_STREAM_ID)
-
-        return 1
diff --git a/synapse/storage/devices.py b/synapse/storage/devices.py
index 79a58df591..111bfb3d64 100644
--- a/synapse/storage/devices.py
+++ b/synapse/storage/devices.py
@@ -512,17 +512,9 @@ class DeviceWorkerStore(SQLBaseStore):
         return results
 
 
-class DeviceStore(DeviceWorkerStore, BackgroundUpdateStore):
+class DeviceBackgroundUpdateStore(BackgroundUpdateStore):
     def __init__(self, db_conn, hs):
-        super(DeviceStore, self).__init__(db_conn, hs)
-
-        # Map of (user_id, device_id) -> bool. If there is an entry that implies
-        # the device exists.
-        self.device_id_exists_cache = Cache(
-            name="device_id_exists", keylen=2, max_entries=10000
-        )
-
-        self._clock.looping_call(self._prune_old_outbound_device_pokes, 60 * 60 * 1000)
+        super(DeviceBackgroundUpdateStore, self).__init__(db_conn, hs)
 
         self.register_background_index_update(
             "device_lists_stream_idx",
@@ -556,6 +548,31 @@ class DeviceStore(DeviceWorkerStore, BackgroundUpdateStore):
         )
 
     @defer.inlineCallbacks
+    def _drop_device_list_streams_non_unique_indexes(self, progress, batch_size):
+        def f(conn):
+            txn = conn.cursor()
+            txn.execute("DROP INDEX IF EXISTS device_lists_remote_cache_id")
+            txn.execute("DROP INDEX IF EXISTS device_lists_remote_extremeties_id")
+            txn.close()
+
+        yield self.runWithConnection(f)
+        yield self._end_background_update(DROP_DEVICE_LIST_STREAMS_NON_UNIQUE_INDEXES)
+        return 1
+
+
+class DeviceStore(DeviceWorkerStore, DeviceBackgroundUpdateStore):
+    def __init__(self, db_conn, hs):
+        super(DeviceStore, self).__init__(db_conn, hs)
+
+        # Map of (user_id, device_id) -> bool. If there is an entry that implies
+        # the device exists.
+        self.device_id_exists_cache = Cache(
+            name="device_id_exists", keylen=2, max_entries=10000
+        )
+
+        self._clock.looping_call(self._prune_old_outbound_device_pokes, 60 * 60 * 1000)
+
+    @defer.inlineCallbacks
     def store_device(self, user_id, device_id, initial_device_display_name):
         """Ensure the given device is known; add it to the store if not
 
@@ -910,15 +927,3 @@ class DeviceStore(DeviceWorkerStore, BackgroundUpdateStore):
             "_prune_old_outbound_device_pokes",
             _prune_txn,
         )
-
-    @defer.inlineCallbacks
-    def _drop_device_list_streams_non_unique_indexes(self, progress, batch_size):
-        def f(conn):
-            txn = conn.cursor()
-            txn.execute("DROP INDEX IF EXISTS device_lists_remote_cache_id")
-            txn.execute("DROP INDEX IF EXISTS device_lists_remote_extremeties_id")
-            txn.close()
-
-        yield self.runWithConnection(f)
-        yield self._end_background_update(DROP_DEVICE_LIST_STREAMS_NON_UNIQUE_INDEXES)
-        return 1
diff --git a/synapse/storage/engines/postgres.py b/synapse/storage/engines/postgres.py
index 289b6bc281..601617b21e 100644
--- a/synapse/storage/engines/postgres.py
+++ b/synapse/storage/engines/postgres.py
@@ -72,6 +72,13 @@ class PostgresEngine(object):
         """
         return True
 
+    @property
+    def supports_tuple_comparison(self):
+        """
+        Do we support comparing tuples, i.e. `(a, b) > (c, d)`?
+        """
+        return True
+
     def is_deadlock(self, error):
         if isinstance(error, self.module.DatabaseError):
             # https://www.postgresql.org/docs/current/static/errcodes-appendix.html
diff --git a/synapse/storage/engines/sqlite.py b/synapse/storage/engines/sqlite.py
index e9b9caa49a..ac92109366 100644
--- a/synapse/storage/engines/sqlite.py
+++ b/synapse/storage/engines/sqlite.py
@@ -38,6 +38,14 @@ class Sqlite3Engine(object):
         """
         return self.module.sqlite_version_info >= (3, 24, 0)
 
+    @property
+    def supports_tuple_comparison(self):
+        """
+        Do we support comparing tuples, i.e. `(a, b) > (c, d)`? This requires
+        SQLite 3.15+.
+        """
+        return self.module.sqlite_version_info >= (3, 15, 0)
+
     def check_database(self, txn):
         pass
 
diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index ddf7ab6479..bb6ff0595a 100644
--- a/synapse/storage/events.py
+++ b/synapse/storage/events.py
@@ -23,7 +23,7 @@ from functools import wraps
 from six import iteritems, text_type
 from six.moves import range
 
-from canonicaljson import encode_canonical_json, json
+from canonicaljson import json
 from prometheus_client import Counter, Histogram
 
 from twisted.internet import defer
@@ -1389,6 +1389,18 @@ class EventsStore(
             ],
         )
 
+        for event, _ in events_and_contexts:
+            if not event.internal_metadata.is_redacted():
+                # If we're persisting an unredacted event we go and ensure
+                # that we mark any redactions that reference this event as
+                # requiring censoring.
+                self._simple_update_txn(
+                    txn,
+                    table="redactions",
+                    keyvalues={"redacts": event.event_id},
+                    updatevalues={"have_censored": False},
+                )
+
     def _store_rejected_events_txn(self, txn, events_and_contexts):
         """Add rows to the 'rejections' table for received events which were
         rejected
@@ -1552,9 +1564,15 @@ class EventsStore(
     def _store_redaction(self, txn, event):
         # invalidate the cache for the redacted event
         txn.call_after(self._invalidate_get_event_cache, event.redacts)
-        txn.execute(
-            "INSERT INTO redactions (event_id, redacts) VALUES (?,?)",
-            (event.event_id, event.redacts),
+
+        self._simple_insert_txn(
+            txn,
+            table="redactions",
+            values={
+                "event_id": event.event_id,
+                "redacts": event.redacts,
+                "received_ts": self._clock.time_msec(),
+            },
         )
 
     @defer.inlineCallbacks
@@ -1571,36 +1589,29 @@ class EventsStore(
         if self.hs.config.redaction_retention_period is None:
             return
 
-        max_pos = yield self.find_first_stream_ordering_after_ts(
-            self._clock.time_msec() - self.hs.config.redaction_retention_period
-        )
+        before_ts = self._clock.time_msec() - self.hs.config.redaction_retention_period
 
         # We fetch all redactions that:
         #   1. point to an event we have,
-        #   2. has a stream ordering from before the cut off, and
+        #   2. has a received_ts from before the cut off, and
         #   3. we haven't yet censored.
         #
         # This is limited to 100 events to ensure that we don't try and do too
         # much at once. We'll get called again so this should eventually catch
         # up.
-        #
-        # We use the range [-max_pos, max_pos] to handle backfilled events,
-        # which are given negative stream ordering.
         sql = """
-            SELECT redact_event.event_id, redacts FROM redactions
-            INNER JOIN events AS redact_event USING (event_id)
-            INNER JOIN events AS original_event ON (
-                redact_event.room_id = original_event.room_id
-                AND redacts = original_event.event_id
+            SELECT redactions.event_id, redacts FROM redactions
+            LEFT JOIN events AS original_event ON (
+                redacts = original_event.event_id
             )
             WHERE NOT have_censored
-            AND ? <= redact_event.stream_ordering AND redact_event.stream_ordering <= ?
-            ORDER BY redact_event.stream_ordering ASC
+            AND redactions.received_ts <= ?
+            ORDER BY redactions.received_ts ASC
             LIMIT ?
         """
 
         rows = yield self._execute(
-            "_censor_redactions_fetch", None, sql, -max_pos, max_pos, 100
+            "_censor_redactions_fetch", None, sql, before_ts, 100
         )
 
         updates = []
@@ -1621,9 +1632,7 @@ class EventsStore(
                 and original_event.internal_metadata.is_redacted()
             ):
                 # Redaction was allowed
-                pruned_json = encode_canonical_json(
-                    prune_event_dict(original_event.get_dict())
-                )
+                pruned_json = encode_json(prune_event_dict(original_event.get_dict()))
             else:
                 # Redaction wasn't allowed
                 pruned_json = None
diff --git a/synapse/storage/events_bg_updates.py b/synapse/storage/events_bg_updates.py
index 6587f31e2b..5717baf48c 100644
--- a/synapse/storage/events_bg_updates.py
+++ b/synapse/storage/events_bg_updates.py
@@ -67,6 +67,10 @@ class EventsBackgroundUpdatesStore(BackgroundUpdateStore):
             self.DELETE_SOFT_FAILED_EXTREMITIES, self._cleanup_extremities_bg_update
         )
 
+        self.register_background_update_handler(
+            "redactions_received_ts", self._redactions_received_ts
+        )
+
     @defer.inlineCallbacks
     def _background_reindex_fields_sender(self, progress, batch_size):
         target_min_stream_id = progress["target_min_stream_id_inclusive"]
@@ -397,3 +401,60 @@ class EventsBackgroundUpdatesStore(BackgroundUpdateStore):
             )
 
         return num_handled
+
+    @defer.inlineCallbacks
+    def _redactions_received_ts(self, progress, batch_size):
+        """Handles filling out the `received_ts` column in redactions.
+        """
+        last_event_id = progress.get("last_event_id", "")
+
+        def _redactions_received_ts_txn(txn):
+            # Fetch the set of event IDs that we want to update
+            sql = """
+                SELECT event_id FROM redactions
+                WHERE event_id > ?
+                ORDER BY event_id ASC
+                LIMIT ?
+            """
+
+            txn.execute(sql, (last_event_id, batch_size))
+
+            rows = txn.fetchall()
+            if not rows:
+                return 0
+
+            upper_event_id, = rows[-1]
+
+            # Update the redactions with the received_ts.
+            #
+            # Note: Not all events have an associated received_ts, so we
+            # fallback to using origin_server_ts. If we for some reason don't
+            # have an origin_server_ts, lets just use the current timestamp.
+            #
+            # We don't want to leave it null, as then we'll never try and
+            # censor those redactions.
+            sql = """
+                UPDATE redactions
+                SET received_ts = (
+                    SELECT COALESCE(received_ts, origin_server_ts, ?) FROM events
+                    WHERE events.event_id = redactions.event_id
+                )
+                WHERE ? <= event_id AND event_id <= ?
+            """
+
+            txn.execute(sql, (self._clock.time_msec(), last_event_id, upper_event_id))
+
+            self._background_update_progress_txn(
+                txn, "redactions_received_ts", {"last_event_id": upper_event_id}
+            )
+
+            return len(rows)
+
+        count = yield self.runInteraction(
+            "_redactions_received_ts", _redactions_received_ts_txn
+        )
+
+        if not count:
+            yield self._end_background_update("redactions_received_ts")
+
+        return count
diff --git a/synapse/storage/events_worker.py b/synapse/storage/events_worker.py
index c6fa7f82fd..57ce0304e9 100644
--- a/synapse/storage/events_worker.py
+++ b/synapse/storage/events_worker.py
@@ -238,6 +238,20 @@ class EventsWorkerStore(SQLBaseStore):
             # we have to recheck auth now.
 
             if not allow_rejected and entry.event.type == EventTypes.Redaction:
+                if not hasattr(entry.event, "redacts"):
+                    # A redacted redaction doesn't have a `redacts` key, in
+                    # which case lets just withhold the event.
+                    #
+                    # Note: Most of the time if the redactions has been
+                    # redacted we still have the un-redacted event in the DB
+                    # and so we'll still see the `redacts` key. However, this
+                    # isn't always true e.g. if we have censored the event.
+                    logger.debug(
+                        "Withholding redaction event %s as we don't have redacts key",
+                        event_id,
+                    )
+                    continue
+
                 redacted_event_id = entry.event.redacts
                 event_map = yield self._get_events_from_cache_or_db([redacted_event_id])
                 original_event_entry = event_map.get(redacted_event_id)
diff --git a/synapse/storage/media_repository.py b/synapse/storage/media_repository.py
index 6b1238ce4a..84b5f3ad5e 100644
--- a/synapse/storage/media_repository.py
+++ b/synapse/storage/media_repository.py
@@ -15,11 +15,9 @@
 from synapse.storage.background_updates import BackgroundUpdateStore
 
 
-class MediaRepositoryStore(BackgroundUpdateStore):
-    """Persistence for attachments and avatars"""
-
+class MediaRepositoryBackgroundUpdateStore(BackgroundUpdateStore):
     def __init__(self, db_conn, hs):
-        super(MediaRepositoryStore, self).__init__(db_conn, hs)
+        super(MediaRepositoryBackgroundUpdateStore, self).__init__(db_conn, hs)
 
         self.register_background_index_update(
             update_name="local_media_repository_url_idx",
@@ -29,6 +27,13 @@ class MediaRepositoryStore(BackgroundUpdateStore):
             where_clause="url_cache IS NOT NULL",
         )
 
+
+class MediaRepositoryStore(MediaRepositoryBackgroundUpdateStore):
+    """Persistence for attachments and avatars"""
+
+    def __init__(self, db_conn, hs):
+        super(MediaRepositoryStore, self).__init__(db_conn, hs)
+
     def get_local_media(self, media_id):
         """Get the metadata for a local piece of media
         Returns:
diff --git a/synapse/storage/push_rule.py b/synapse/storage/push_rule.py
index 1f878e6575..c4e24edff2 100644
--- a/synapse/storage/push_rule.py
+++ b/synapse/storage/push_rule.py
@@ -183,8 +183,8 @@ class PushRulesWorkerStore(
         return results
 
     @defer.inlineCallbacks
-    def move_push_rule_from_room_to_room(self, new_room_id, user_id, rule):
-        """Move a single push rule from one room to another for a specific user.
+    def copy_push_rule_from_room_to_room(self, new_room_id, user_id, rule):
+        """Copy a single push rule from one room to another for a specific user.
 
         Args:
             new_room_id (str): ID of the new room.
@@ -209,14 +209,11 @@ class PushRulesWorkerStore(
             actions=rule["actions"],
         )
 
-        # Delete push rule for the old room
-        yield self.delete_push_rule(user_id, rule["rule_id"])
-
     @defer.inlineCallbacks
-    def move_push_rules_from_room_to_room_for_user(
+    def copy_push_rules_from_room_to_room_for_user(
         self, old_room_id, new_room_id, user_id
     ):
-        """Move all of the push rules from one room to another for a specific
+        """Copy all of the push rules from one room to another for a specific
         user.
 
         Args:
@@ -227,15 +224,14 @@ class PushRulesWorkerStore(
         # Retrieve push rules for this user
         user_push_rules = yield self.get_push_rules_for_user(user_id)
 
-        # Get rules relating to the old room, move them to the new room, then
-        # delete them from the old room
+        # Get rules relating to the old room and copy them to the new room
         for rule in user_push_rules:
             conditions = rule.get("conditions", [])
             if any(
                 (c.get("key") == "room_id" and c.get("pattern") == old_room_id)
                 for c in conditions
             ):
-                yield self.move_push_rule_from_room_to_room(new_room_id, user_id, rule)
+                yield self.copy_push_rule_from_room_to_room(new_room_id, user_id, rule)
 
     @defer.inlineCallbacks
     def bulk_get_push_rules_for_room(self, event, context):
diff --git a/synapse/storage/registration.py b/synapse/storage/registration.py
index 241a7be51e..6c5b29288a 100644
--- a/synapse/storage/registration.py
+++ b/synapse/storage/registration.py
@@ -493,7 +493,9 @@ class RegistrationWorkerStore(SQLBaseStore):
         """
 
         def _find_next_generated_user_id(txn):
-            txn.execute("SELECT name FROM users")
+            # We bound between '@1' and '@a' to avoid pulling the entire table
+            # out.
+            txn.execute("SELECT name FROM users WHERE '@1' <= name AND name < '@a'")
 
             regex = re.compile(r"^@(\d+):")
 
@@ -785,13 +787,14 @@ class RegistrationWorkerStore(SQLBaseStore):
         )
 
 
-class RegistrationStore(
+class RegistrationBackgroundUpdateStore(
     RegistrationWorkerStore, background_updates.BackgroundUpdateStore
 ):
     def __init__(self, db_conn, hs):
-        super(RegistrationStore, self).__init__(db_conn, hs)
+        super(RegistrationBackgroundUpdateStore, self).__init__(db_conn, hs)
 
         self.clock = hs.get_clock()
+        self.config = hs.config
 
         self.register_background_index_update(
             "access_tokens_device_index",
@@ -807,8 +810,6 @@ class RegistrationStore(
             columns=["creation_ts"],
         )
 
-        self._account_validity = hs.config.account_validity
-
         # we no longer use refresh tokens, but it's possible that some people
         # might have a background update queued to build this index. Just
         # clear the background update.
@@ -822,17 +823,6 @@ class RegistrationStore(
             "users_set_deactivated_flag", self._background_update_set_deactivated_flag
         )
 
-        # Create a background job for culling expired 3PID validity tokens
-        def start_cull():
-            # run as a background process to make sure that the database transactions
-            # have a logcontext to report to
-            return run_as_background_process(
-                "cull_expired_threepid_validation_tokens",
-                self.cull_expired_threepid_validation_tokens,
-            )
-
-        hs.get_clock().looping_call(start_cull, THIRTY_MINUTES_IN_MS)
-
     @defer.inlineCallbacks
     def _background_update_set_deactivated_flag(self, progress, batch_size):
         """Retrieves a list of all deactivated users and sets the 'deactivated' flag to 1
@@ -895,6 +885,54 @@ class RegistrationStore(
         return nb_processed
 
     @defer.inlineCallbacks
+    def _bg_user_threepids_grandfather(self, progress, batch_size):
+        """We now track which identity servers a user binds their 3PID to, so
+        we need to handle the case of existing bindings where we didn't track
+        this.
+
+        We do this by grandfathering in existing user threepids assuming that
+        they used one of the server configured trusted identity servers.
+        """
+        id_servers = set(self.config.trusted_third_party_id_servers)
+
+        def _bg_user_threepids_grandfather_txn(txn):
+            sql = """
+                INSERT INTO user_threepid_id_server
+                    (user_id, medium, address, id_server)
+                SELECT user_id, medium, address, ?
+                FROM user_threepids
+            """
+
+            txn.executemany(sql, [(id_server,) for id_server in id_servers])
+
+        if id_servers:
+            yield self.runInteraction(
+                "_bg_user_threepids_grandfather", _bg_user_threepids_grandfather_txn
+            )
+
+        yield self._end_background_update("user_threepids_grandfather")
+
+        return 1
+
+
+class RegistrationStore(RegistrationBackgroundUpdateStore):
+    def __init__(self, db_conn, hs):
+        super(RegistrationStore, self).__init__(db_conn, hs)
+
+        self._account_validity = hs.config.account_validity
+
+        # Create a background job for culling expired 3PID validity tokens
+        def start_cull():
+            # run as a background process to make sure that the database transactions
+            # have a logcontext to report to
+            return run_as_background_process(
+                "cull_expired_threepid_validation_tokens",
+                self.cull_expired_threepid_validation_tokens,
+            )
+
+        hs.get_clock().looping_call(start_cull, THIRTY_MINUTES_IN_MS)
+
+    @defer.inlineCallbacks
     def add_access_token_to_user(self, user_id, token, device_id, valid_until_ms):
         """Adds an access token for the given user.
 
@@ -1242,36 +1280,6 @@ class RegistrationStore(
             desc="get_users_pending_deactivation",
         )
 
-    @defer.inlineCallbacks
-    def _bg_user_threepids_grandfather(self, progress, batch_size):
-        """We now track which identity servers a user binds their 3PID to, so
-        we need to handle the case of existing bindings where we didn't track
-        this.
-
-        We do this by grandfathering in existing user threepids assuming that
-        they used one of the server configured trusted identity servers.
-        """
-        id_servers = set(self.config.trusted_third_party_id_servers)
-
-        def _bg_user_threepids_grandfather_txn(txn):
-            sql = """
-                INSERT INTO user_threepid_id_server
-                    (user_id, medium, address, id_server)
-                SELECT user_id, medium, address, ?
-                FROM user_threepids
-            """
-
-            txn.executemany(sql, [(id_server,) for id_server in id_servers])
-
-        if id_servers:
-            yield self.runInteraction(
-                "_bg_user_threepids_grandfather", _bg_user_threepids_grandfather_txn
-            )
-
-        yield self._end_background_update("user_threepids_grandfather")
-
-        return 1
-
     def validate_threepid_session(self, session_id, client_secret, token, current_ts):
         """Attempt to validate a threepid session using a token
 
@@ -1463,17 +1471,6 @@ class RegistrationStore(
             self.clock.time_msec(),
         )
 
-    def set_user_deactivated_status_txn(self, txn, user_id, deactivated):
-        self._simple_update_one_txn(
-            txn=txn,
-            table="users",
-            keyvalues={"name": user_id},
-            updatevalues={"deactivated": 1 if deactivated else 0},
-        )
-        self._invalidate_cache_and_stream(
-            txn, self.get_user_deactivated_status, (user_id,)
-        )
-
     @defer.inlineCallbacks
     def set_user_deactivated_status(self, user_id, deactivated):
         """Set the `deactivated` property for the provided user to the provided value.
@@ -1489,3 +1486,14 @@ class RegistrationStore(
             user_id,
             deactivated,
         )
+
+    def set_user_deactivated_status_txn(self, txn, user_id, deactivated):
+        self._simple_update_one_txn(
+            txn=txn,
+            table="users",
+            keyvalues={"name": user_id},
+            updatevalues={"deactivated": 1 if deactivated else 0},
+        )
+        self._invalidate_cache_and_stream(
+            txn, self.get_user_deactivated_status, (user_id,)
+        )
diff --git a/synapse/storage/room.py b/synapse/storage/room.py
index 08e13f3a3b..43cc56fa6f 100644
--- a/synapse/storage/room.py
+++ b/synapse/storage/room.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 # Copyright 2014-2016 OpenMarket Ltd
+# Copyright 2019 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -16,6 +17,7 @@
 import collections
 import logging
 import re
+from typing import Optional, Tuple
 
 from canonicaljson import json
 
@@ -24,6 +26,7 @@ from twisted.internet import defer
 from synapse.api.errors import StoreError
 from synapse.storage._base import SQLBaseStore
 from synapse.storage.search import SearchStore
+from synapse.types import ThirdPartyInstanceID
 from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
 
 logger = logging.getLogger(__name__)
@@ -63,103 +66,196 @@ class RoomWorkerStore(SQLBaseStore):
             desc="get_public_room_ids",
         )
 
-    @cached(num_args=2, max_entries=100)
-    def get_public_room_ids_at_stream_id(self, stream_id, network_tuple):
-        """Get pulbic rooms for a particular list, or across all lists.
+    def count_public_rooms(self, network_tuple, ignore_non_federatable):
+        """Counts the number of public rooms as tracked in the room_stats_current
+        and room_stats_state table.
 
         Args:
-            stream_id (int)
-            network_tuple (ThirdPartyInstanceID): The list to use (None, None)
-                means the main list, None means all lsits.
+            network_tuple (ThirdPartyInstanceID|None)
+            ignore_non_federatable (bool): If true filters out non-federatable rooms
         """
-        return self.runInteraction(
-            "get_public_room_ids_at_stream_id",
-            self.get_public_room_ids_at_stream_id_txn,
-            stream_id,
-            network_tuple=network_tuple,
-        )
-
-    def get_public_room_ids_at_stream_id_txn(self, txn, stream_id, network_tuple):
-        return {
-            rm
-            for rm, vis in self.get_published_at_stream_id_txn(
-                txn, stream_id, network_tuple=network_tuple
-            ).items()
-            if vis
-        }
 
-    def get_published_at_stream_id_txn(self, txn, stream_id, network_tuple):
-        if network_tuple:
-            # We want to get from a particular list. No aggregation required.
+        def _count_public_rooms_txn(txn):
+            query_args = []
+
+            if network_tuple:
+                if network_tuple.appservice_id:
+                    published_sql = """
+                        SELECT room_id from appservice_room_list
+                        WHERE appservice_id = ? AND network_id = ?
+                    """
+                    query_args.append(network_tuple.appservice_id)
+                    query_args.append(network_tuple.network_id)
+                else:
+                    published_sql = """
+                        SELECT room_id FROM rooms WHERE is_public
+                    """
+            else:
+                published_sql = """
+                    SELECT room_id FROM rooms WHERE is_public
+                    UNION SELECT room_id from appservice_room_list
+            """
 
             sql = """
-                SELECT room_id, visibility FROM public_room_list_stream
-                INNER JOIN (
-                    SELECT room_id, max(stream_id) AS stream_id
-                    FROM public_room_list_stream
-                    WHERE stream_id <= ? %s
-                    GROUP BY room_id
-                ) grouped USING (room_id, stream_id)
+                SELECT
+                    COALESCE(COUNT(*), 0)
+                FROM (
+                    %(published_sql)s
+                ) published
+                INNER JOIN room_stats_state USING (room_id)
+                INNER JOIN room_stats_current USING (room_id)
+                WHERE
+                    (
+                        join_rules = 'public' OR history_visibility = 'world_readable'
+                    )
+                    AND joined_members > 0
+            """ % {
+                "published_sql": published_sql
+            }
+
+            txn.execute(sql, query_args)
+            return txn.fetchone()[0]
+
+        return self.runInteraction("count_public_rooms", _count_public_rooms_txn)
+
+    @defer.inlineCallbacks
+    def get_largest_public_rooms(
+        self,
+        network_tuple: Optional[ThirdPartyInstanceID],
+        search_filter: Optional[dict],
+        limit: Optional[int],
+        bounds: Optional[Tuple[int, str]],
+        forwards: bool,
+        ignore_non_federatable: bool = False,
+    ):
+        """Gets the largest public rooms (where largest is in terms of joined
+        members, as tracked in the statistics table).
+
+        Args:
+            network_tuple
+            search_filter
+            limit: Maxmimum number of rows to return, unlimited otherwise.
+            bounds: An uppoer or lower bound to apply to result set if given,
+                consists of a joined member count and room_id (these are
+                excluded from result set).
+            forwards: true iff going forwards, going backwards otherwise
+            ignore_non_federatable: If true filters out non-federatable rooms.
+
+        Returns:
+            Rooms in order: biggest number of joined users first.
+            We then arbitrarily use the room_id as a tie breaker.
+
+        """
+
+        where_clauses = []
+        query_args = []
+
+        if network_tuple:
+            if network_tuple.appservice_id:
+                published_sql = """
+                    SELECT room_id from appservice_room_list
+                    WHERE appservice_id = ? AND network_id = ?
+                """
+                query_args.append(network_tuple.appservice_id)
+                query_args.append(network_tuple.network_id)
+            else:
+                published_sql = """
+                    SELECT room_id FROM rooms WHERE is_public
+                """
+        else:
+            published_sql = """
+                SELECT room_id FROM rooms WHERE is_public
+                UNION SELECT room_id from appservice_room_list
             """
 
-            if network_tuple.appservice_id is not None:
-                txn.execute(
-                    sql % ("AND appservice_id = ? AND network_id = ?",),
-                    (stream_id, network_tuple.appservice_id, network_tuple.network_id),
+        # Work out the bounds if we're given them, these bounds look slightly
+        # odd, but are designed to help query planner use indices by pulling
+        # out a common bound.
+        if bounds:
+            last_joined_members, last_room_id = bounds
+            if forwards:
+                where_clauses.append(
+                    """
+                        joined_members <= ? AND (
+                            joined_members < ? OR room_id < ?
+                        )
+                    """
                 )
             else:
-                txn.execute(sql % ("AND appservice_id IS NULL",), (stream_id,))
-            return dict(txn)
-        else:
-            # We want to get from all lists, so we need to aggregate the results
+                where_clauses.append(
+                    """
+                        joined_members >= ? AND (
+                            joined_members > ? OR room_id > ?
+                        )
+                    """
+                )
 
-            logger.info("Executing full list")
+            query_args += [last_joined_members, last_joined_members, last_room_id]
 
-            sql = """
-                SELECT room_id, visibility
-                FROM public_room_list_stream
-                INNER JOIN (
-                    SELECT
-                        room_id, max(stream_id) AS stream_id, appservice_id,
-                        network_id
-                    FROM public_room_list_stream
-                    WHERE stream_id <= ?
-                    GROUP BY room_id, appservice_id, network_id
-                ) grouped USING (room_id, stream_id)
-            """
+        if ignore_non_federatable:
+            where_clauses.append("is_federatable")
 
-            txn.execute(sql, (stream_id,))
+        if search_filter and search_filter.get("generic_search_term", None):
+            search_term = "%" + search_filter["generic_search_term"] + "%"
 
-            results = {}
-            # A room is visible if its visible on any list.
-            for room_id, visibility in txn:
-                results[room_id] = bool(visibility) or results.get(room_id, False)
+            where_clauses.append(
+                """
+                    (
+                        name LIKE ?
+                        OR topic LIKE ?
+                        OR canonical_alias LIKE ?
+                    )
+                """
+            )
+            query_args += [search_term, search_term, search_term]
+
+        where_clause = ""
+        if where_clauses:
+            where_clause = " AND " + " AND ".join(where_clauses)
+
+        sql = """
+            SELECT
+                room_id, name, topic, canonical_alias, joined_members,
+                avatar, history_visibility, joined_members, guest_access
+            FROM (
+                %(published_sql)s
+            ) published
+            INNER JOIN room_stats_state USING (room_id)
+            INNER JOIN room_stats_current USING (room_id)
+            WHERE
+                (
+                    join_rules = 'public' OR history_visibility = 'world_readable'
+                )
+                AND joined_members > 0
+                %(where_clause)s
+            ORDER BY joined_members %(dir)s, room_id %(dir)s
+        """ % {
+            "published_sql": published_sql,
+            "where_clause": where_clause,
+            "dir": "DESC" if forwards else "ASC",
+        }
 
-            return results
+        if limit is not None:
+            query_args.append(limit)
 
-    def get_public_room_changes(self, prev_stream_id, new_stream_id, network_tuple):
-        def get_public_room_changes_txn(txn):
-            then_rooms = self.get_public_room_ids_at_stream_id_txn(
-                txn, prev_stream_id, network_tuple
-            )
+            sql += """
+                LIMIT ?
+            """
 
-            now_rooms_dict = self.get_published_at_stream_id_txn(
-                txn, new_stream_id, network_tuple
-            )
+        def _get_largest_public_rooms_txn(txn):
+            txn.execute(sql, query_args)
 
-            now_rooms_visible = set(rm for rm, vis in now_rooms_dict.items() if vis)
-            now_rooms_not_visible = set(
-                rm for rm, vis in now_rooms_dict.items() if not vis
-            )
+            results = self.cursor_to_dict(txn)
 
-            newly_visible = now_rooms_visible - then_rooms
-            newly_unpublished = now_rooms_not_visible & then_rooms
+            if not forwards:
+                results.reverse()
 
-            return newly_visible, newly_unpublished
+            return results
 
-        return self.runInteraction(
-            "get_public_room_changes", get_public_room_changes_txn
+        ret_val = yield self.runInteraction(
+            "get_largest_public_rooms", _get_largest_public_rooms_txn
         )
+        defer.returnValue(ret_val)
 
     @cached(max_entries=10000)
     def is_room_blocked(self, room_id):
diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index 4df8ebdacd..4e606a8380 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -27,12 +27,14 @@ from synapse.api.constants import EventTypes, Membership
 from synapse.metrics import LaterGauge
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.storage._base import LoggingTransaction
+from synapse.storage.background_updates import BackgroundUpdateStore
 from synapse.storage.engines import Sqlite3Engine
 from synapse.storage.events_worker import EventsWorkerStore
 from synapse.types import get_domain_from_id
 from synapse.util.async_helpers import Linearizer
 from synapse.util.caches import intern_string
-from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
+from synapse.util.caches.descriptors import cached, cachedInlineCallbacks, cachedList
+from synapse.util.metrics import Measure
 from synapse.util.stringutils import to_ascii
 
 logger = logging.getLogger(__name__)
@@ -483,6 +485,7 @@ class RoomMemberWorkerStore(EventsWorkerStore):
         )
         return result
 
+    @defer.inlineCallbacks
     def get_joined_users_from_state(self, room_id, state_entry):
         state_group = state_entry.state_group
         if not state_group:
@@ -492,9 +495,12 @@ class RoomMemberWorkerStore(EventsWorkerStore):
             # To do this we set the state_group to a new object as object() != object()
             state_group = object()
 
-        return self._get_joined_users_from_context(
-            room_id, state_group, state_entry.state, context=state_entry
-        )
+        with Measure(self._clock, "get_joined_users_from_state"):
+            return (
+                yield self._get_joined_users_from_context(
+                    room_id, state_group, state_entry.state, context=state_entry
+                )
+            )
 
     @cachedInlineCallbacks(
         num_args=2, cache_context=True, iterable=True, max_entries=100000
@@ -567,25 +573,10 @@ class RoomMemberWorkerStore(EventsWorkerStore):
                 missing_member_event_ids.append(event_id)
 
         if missing_member_event_ids:
-            rows = yield self._simple_select_many_batch(
-                table="room_memberships",
-                column="event_id",
-                iterable=missing_member_event_ids,
-                retcols=("user_id", "display_name", "avatar_url"),
-                keyvalues={"membership": Membership.JOIN},
-                batch_size=500,
-                desc="_get_joined_users_from_context",
-            )
-
-            users_in_room.update(
-                {
-                    to_ascii(row["user_id"]): ProfileInfo(
-                        avatar_url=to_ascii(row["avatar_url"]),
-                        display_name=to_ascii(row["display_name"]),
-                    )
-                    for row in rows
-                }
+            event_to_memberships = yield self._get_joined_profiles_from_event_ids(
+                missing_member_event_ids
             )
+            users_in_room.update((row for row in event_to_memberships.values() if row))
 
         if event is not None and event.type == EventTypes.Member:
             if event.membership == Membership.JOIN:
@@ -597,6 +588,47 @@ class RoomMemberWorkerStore(EventsWorkerStore):
 
         return users_in_room
 
+    @cached(max_entries=10000)
+    def _get_joined_profile_from_event_id(self, event_id):
+        raise NotImplementedError()
+
+    @cachedList(
+        cached_method_name="_get_joined_profile_from_event_id",
+        list_name="event_ids",
+        inlineCallbacks=True,
+    )
+    def _get_joined_profiles_from_event_ids(self, event_ids):
+        """For given set of member event_ids check if they point to a join
+        event and if so return the associated user and profile info.
+
+        Args:
+            event_ids (Iterable[str]): The member event IDs to lookup
+
+        Returns:
+            Deferred[dict[str, Tuple[str, ProfileInfo]|None]]: Map from event ID
+            to `user_id` and ProfileInfo (or None if not join event).
+        """
+
+        rows = yield self._simple_select_many_batch(
+            table="room_memberships",
+            column="event_id",
+            iterable=event_ids,
+            retcols=("user_id", "display_name", "avatar_url", "event_id"),
+            keyvalues={"membership": Membership.JOIN},
+            batch_size=500,
+            desc="_get_membership_from_event_ids",
+        )
+
+        return {
+            row["event_id"]: (
+                row["user_id"],
+                ProfileInfo(
+                    avatar_url=row["avatar_url"], display_name=row["display_name"]
+                ),
+            )
+            for row in rows
+        }
+
     @cachedInlineCallbacks(max_entries=10000)
     def is_host_joined(self, room_id, host):
         if "%" in host or "_" in host:
@@ -669,6 +701,7 @@ class RoomMemberWorkerStore(EventsWorkerStore):
 
         return True
 
+    @defer.inlineCallbacks
     def get_joined_hosts(self, room_id, state_entry):
         state_group = state_entry.state_group
         if not state_group:
@@ -678,9 +711,12 @@ class RoomMemberWorkerStore(EventsWorkerStore):
             # To do this we set the state_group to a new object as object() != object()
             state_group = object()
 
-        return self._get_joined_hosts(
-            room_id, state_group, state_entry.state, state_entry=state_entry
-        )
+        with Measure(self._clock, "get_joined_hosts"):
+            return (
+                yield self._get_joined_hosts(
+                    room_id, state_group, state_entry.state, state_entry=state_entry
+                )
+            )
 
     @cachedInlineCallbacks(num_args=2, max_entries=10000, iterable=True)
     # @defer.inlineCallbacks
@@ -785,9 +821,9 @@ class RoomMemberWorkerStore(EventsWorkerStore):
         return set(room_ids)
 
 
-class RoomMemberStore(RoomMemberWorkerStore):
+class RoomMemberBackgroundUpdateStore(BackgroundUpdateStore):
     def __init__(self, db_conn, hs):
-        super(RoomMemberStore, self).__init__(db_conn, hs)
+        super(RoomMemberBackgroundUpdateStore, self).__init__(db_conn, hs)
         self.register_background_update_handler(
             _MEMBERSHIP_PROFILE_UPDATE_NAME, self._background_add_membership_profile
         )
@@ -803,112 +839,6 @@ class RoomMemberStore(RoomMemberWorkerStore):
             where_clause="forgotten = 1",
         )
 
-    def _store_room_members_txn(self, txn, events, backfilled):
-        """Store a room member in the database.
-        """
-        self._simple_insert_many_txn(
-            txn,
-            table="room_memberships",
-            values=[
-                {
-                    "event_id": event.event_id,
-                    "user_id": event.state_key,
-                    "sender": event.user_id,
-                    "room_id": event.room_id,
-                    "membership": event.membership,
-                    "display_name": event.content.get("displayname", None),
-                    "avatar_url": event.content.get("avatar_url", None),
-                }
-                for event in events
-            ],
-        )
-
-        for event in events:
-            txn.call_after(
-                self._membership_stream_cache.entity_has_changed,
-                event.state_key,
-                event.internal_metadata.stream_ordering,
-            )
-            txn.call_after(
-                self.get_invited_rooms_for_user.invalidate, (event.state_key,)
-            )
-
-            # We update the local_invites table only if the event is "current",
-            # i.e., its something that has just happened. If the event is an
-            # outlier it is only current if its an "out of band membership",
-            # like a remote invite or a rejection of a remote invite.
-            is_new_state = not backfilled and (
-                not event.internal_metadata.is_outlier()
-                or event.internal_metadata.is_out_of_band_membership()
-            )
-            is_mine = self.hs.is_mine_id(event.state_key)
-            if is_new_state and is_mine:
-                if event.membership == Membership.INVITE:
-                    self._simple_insert_txn(
-                        txn,
-                        table="local_invites",
-                        values={
-                            "event_id": event.event_id,
-                            "invitee": event.state_key,
-                            "inviter": event.sender,
-                            "room_id": event.room_id,
-                            "stream_id": event.internal_metadata.stream_ordering,
-                        },
-                    )
-                else:
-                    sql = (
-                        "UPDATE local_invites SET stream_id = ?, replaced_by = ? WHERE"
-                        " room_id = ? AND invitee = ? AND locally_rejected is NULL"
-                        " AND replaced_by is NULL"
-                    )
-
-                    txn.execute(
-                        sql,
-                        (
-                            event.internal_metadata.stream_ordering,
-                            event.event_id,
-                            event.room_id,
-                            event.state_key,
-                        ),
-                    )
-
-    @defer.inlineCallbacks
-    def locally_reject_invite(self, user_id, room_id):
-        sql = (
-            "UPDATE local_invites SET stream_id = ?, locally_rejected = ? WHERE"
-            " room_id = ? AND invitee = ? AND locally_rejected is NULL"
-            " AND replaced_by is NULL"
-        )
-
-        def f(txn, stream_ordering):
-            txn.execute(sql, (stream_ordering, True, room_id, user_id))
-
-        with self._stream_id_gen.get_next() as stream_ordering:
-            yield self.runInteraction("locally_reject_invite", f, stream_ordering)
-
-    def forget(self, user_id, room_id):
-        """Indicate that user_id wishes to discard history for room_id."""
-
-        def f(txn):
-            sql = (
-                "UPDATE"
-                "  room_memberships"
-                " SET"
-                "  forgotten = 1"
-                " WHERE"
-                "  user_id = ?"
-                " AND"
-                "  room_id = ?"
-            )
-            txn.execute(sql, (user_id, room_id))
-
-            self._invalidate_cache_and_stream(txn, self.did_forget, (user_id, room_id))
-            self._invalidate_cache_and_stream(
-                txn, self.get_forgotten_rooms_for_user, (user_id,)
-            )
-
-        return self.runInteraction("forget_membership", f)
-
     @defer.inlineCallbacks
     def _background_add_membership_profile(self, progress, batch_size):
         target_min_stream_id = progress.get(
@@ -1043,6 +973,117 @@ class RoomMemberStore(RoomMemberWorkerStore):
         return row_count
 
 
+class RoomMemberStore(RoomMemberWorkerStore, RoomMemberBackgroundUpdateStore):
+    def __init__(self, db_conn, hs):
+        super(RoomMemberStore, self).__init__(db_conn, hs)
+
+    def _store_room_members_txn(self, txn, events, backfilled):
+        """Store a room member in the database.
+        """
+        self._simple_insert_many_txn(
+            txn,
+            table="room_memberships",
+            values=[
+                {
+                    "event_id": event.event_id,
+                    "user_id": event.state_key,
+                    "sender": event.user_id,
+                    "room_id": event.room_id,
+                    "membership": event.membership,
+                    "display_name": event.content.get("displayname", None),
+                    "avatar_url": event.content.get("avatar_url", None),
+                }
+                for event in events
+            ],
+        )
+
+        for event in events:
+            txn.call_after(
+                self._membership_stream_cache.entity_has_changed,
+                event.state_key,
+                event.internal_metadata.stream_ordering,
+            )
+            txn.call_after(
+                self.get_invited_rooms_for_user.invalidate, (event.state_key,)
+            )
+
+            # We update the local_invites table only if the event is "current",
+            # i.e., its something that has just happened. If the event is an
+            # outlier it is only current if its an "out of band membership",
+            # like a remote invite or a rejection of a remote invite.
+            is_new_state = not backfilled and (
+                not event.internal_metadata.is_outlier()
+                or event.internal_metadata.is_out_of_band_membership()
+            )
+            is_mine = self.hs.is_mine_id(event.state_key)
+            if is_new_state and is_mine:
+                if event.membership == Membership.INVITE:
+                    self._simple_insert_txn(
+                        txn,
+                        table="local_invites",
+                        values={
+                            "event_id": event.event_id,
+                            "invitee": event.state_key,
+                            "inviter": event.sender,
+                            "room_id": event.room_id,
+                            "stream_id": event.internal_metadata.stream_ordering,
+                        },
+                    )
+                else:
+                    sql = (
+                        "UPDATE local_invites SET stream_id = ?, replaced_by = ? WHERE"
+                        " room_id = ? AND invitee = ? AND locally_rejected is NULL"
+                        " AND replaced_by is NULL"
+                    )
+
+                    txn.execute(
+                        sql,
+                        (
+                            event.internal_metadata.stream_ordering,
+                            event.event_id,
+                            event.room_id,
+                            event.state_key,
+                        ),
+                    )
+
+    @defer.inlineCallbacks
+    def locally_reject_invite(self, user_id, room_id):
+        sql = (
+            "UPDATE local_invites SET stream_id = ?, locally_rejected = ? WHERE"
+            " room_id = ? AND invitee = ? AND locally_rejected is NULL"
+            " AND replaced_by is NULL"
+        )
+
+        def f(txn, stream_ordering):
+            txn.execute(sql, (stream_ordering, True, room_id, user_id))
+
+        with self._stream_id_gen.get_next() as stream_ordering:
+            yield self.runInteraction("locally_reject_invite", f, stream_ordering)
+
+    def forget(self, user_id, room_id):
+        """Indicate that user_id wishes to discard history for room_id."""
+
+        def f(txn):
+            sql = (
+                "UPDATE"
+                "  room_memberships"
+                " SET"
+                "  forgotten = 1"
+                " WHERE"
+                "  user_id = ?"
+                " AND"
+                "  room_id = ?"
+            )
+            txn.execute(sql, (user_id, room_id))
+
+            self._invalidate_cache_and_stream(txn, self.did_forget, (user_id, room_id))
+            self._invalidate_cache_and_stream(
+                txn, self.get_forgotten_rooms_for_user, (user_id,)
+            )
+
+        return self.runInteraction("forget_membership", f)
+
+
 class _JoinedHostsCache(object):
     """Cache for joined hosts in a room that is optimised to handle updates
     via state deltas.
diff --git a/synapse/storage/schema/delta/56/destinations_retry_interval_type.sql.postgres b/synapse/storage/schema/delta/56/destinations_retry_interval_type.sql.postgres
new file mode 100644
index 0000000000..b9bbb18a91
--- /dev/null
+++ b/synapse/storage/schema/delta/56/destinations_retry_interval_type.sql.postgres
@@ -0,0 +1,18 @@
+/* Copyright 2019 The Matrix.org Foundation C.I.C
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+-- We want to store large retry intervals so we upgrade the column from INT
+-- to BIGINT. We don't need to do this on SQLite.
+ALTER TABLE destinations ALTER retry_interval SET DATA TYPE BIGINT;
diff --git a/synapse/storage/schema/delta/56/drop_unused_event_tables.sql b/synapse/storage/schema/delta/56/drop_unused_event_tables.sql
new file mode 100644
index 0000000000..9f09922c67
--- /dev/null
+++ b/synapse/storage/schema/delta/56/drop_unused_event_tables.sql
@@ -0,0 +1,20 @@
+/* Copyright 2019 The Matrix.org Foundation C.I.C.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+-- these tables are never used.
+DROP TABLE IF EXISTS room_names;
+DROP TABLE IF EXISTS topics;
+DROP TABLE IF EXISTS history_visibility;
+DROP TABLE IF EXISTS guest_access;
diff --git a/synapse/storage/schema/delta/56/public_room_list_idx.sql b/synapse/storage/schema/delta/56/public_room_list_idx.sql
new file mode 100644
index 0000000000..7be31ffebb
--- /dev/null
+++ b/synapse/storage/schema/delta/56/public_room_list_idx.sql
@@ -0,0 +1,16 @@
+/* Copyright 2019 The Matrix.org Foundation C.I.C.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+CREATE INDEX public_room_list_stream_network ON public_room_list_stream (appservice_id, network_id, room_id);
diff --git a/synapse/storage/schema/delta/56/redaction_censor2.sql b/synapse/storage/schema/delta/56/redaction_censor2.sql
new file mode 100644
index 0000000000..77a5eca499
--- /dev/null
+++ b/synapse/storage/schema/delta/56/redaction_censor2.sql
@@ -0,0 +1,20 @@
+/* Copyright 2019 The Matrix.org Foundation C.I.C.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+ALTER TABLE redactions ADD COLUMN received_ts BIGINT;
+CREATE INDEX redactions_have_censored_ts ON redactions(received_ts) WHERE not have_censored;
+
+INSERT INTO background_updates (update_name, progress_json) VALUES
+  ('redactions_received_ts', '{}');
diff --git a/synapse/storage/schema/delta/56/redaction_censor3_fix_update.sql.postgres b/synapse/storage/schema/delta/56/redaction_censor3_fix_update.sql.postgres
new file mode 100644
index 0000000000..f7bcc5e2f2
--- /dev/null
+++ b/synapse/storage/schema/delta/56/redaction_censor3_fix_update.sql.postgres
@@ -0,0 +1,26 @@
+/* Copyright 2019 The Matrix.org Foundation C.I.C.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+-- There was a bug where we may have updated censored redactions as bytes,
+-- which can (somehow) cause json to be inserted hex encoded. This goes and
+-- undoes any such hex encoded JSON.
+UPDATE event_json SET json = convert_from(json::bytea, 'utf8')
+WHERE event_id IN (
+  SELECT event_json.event_id
+  FROM event_json
+  INNER JOIN redactions ON (event_json.event_id = redacts)
+  WHERE have_censored AND json NOT LIKE '{%'
+);
diff --git a/synapse/storage/schema/delta/56/unique_user_filter_index.py b/synapse/storage/schema/delta/56/unique_user_filter_index.py
new file mode 100644
index 0000000000..60031f23ca
--- /dev/null
+++ b/synapse/storage/schema/delta/56/unique_user_filter_index.py
@@ -0,0 +1,46 @@
+import logging
+
+from synapse.storage.engines import PostgresEngine
+
+logger = logging.getLogger(__name__)
+
+
+def run_upgrade(cur, database_engine, *args, **kwargs):
+    if isinstance(database_engine, PostgresEngine):
+        select_clause = """
+        CREATE TEMPORARY TABLE user_filters_migration AS
+            SELECT DISTINCT ON (user_id, filter_id) user_id, filter_id, filter_json
+            FROM user_filters;
+        """
+    else:
+        select_clause = """
+        CREATE TEMPORARY TABLE user_filters_migration AS
+            SELECT * FROM user_filters GROUP BY user_id, filter_id;
+        """
+    sql = (
+        """
+        BEGIN;
+            %s
+            DROP INDEX user_filters_by_user_id_filter_id;
+            DELETE FROM user_filters;
+            ALTER TABLE user_filters
+               ALTER COLUMN user_id SET NOT NULL,
+               ALTER COLUMN filter_id SET NOT NULL,
+               ALTER COLUMN filter_json SET NOT NULL;
+            INSERT INTO user_filters(user_id, filter_id, filter_json)
+                SELECT * FROM user_filters_migration;
+            DROP TABLE user_filters_migration;
+            CREATE UNIQUE INDEX user_filters_by_user_id_filter_id_unique
+                ON user_filters(user_id, filter_id);
+        END;
+    """
+        % select_clause
+    )
+    if isinstance(database_engine, PostgresEngine):
+        cur.execute(sql)
+    else:
+        cur.executescript(sql)
+
+
+def run_create(cur, database_engine, *args, **kwargs):
+    pass
diff --git a/synapse/storage/search.py b/synapse/storage/search.py
index df87ab6a6d..6ba4190f1a 100644
--- a/synapse/storage/search.py
+++ b/synapse/storage/search.py
@@ -36,7 +36,7 @@ SearchEntry = namedtuple(
 )
 
 
-class SearchStore(BackgroundUpdateStore):
+class SearchBackgroundUpdateStore(BackgroundUpdateStore):
 
     EVENT_SEARCH_UPDATE_NAME = "event_search"
     EVENT_SEARCH_ORDER_UPDATE_NAME = "event_search_order"
@@ -44,7 +44,7 @@ class SearchStore(BackgroundUpdateStore):
     EVENT_SEARCH_USE_GIN_POSTGRES_NAME = "event_search_postgres_gin"
 
     def __init__(self, db_conn, hs):
-        super(SearchStore, self).__init__(db_conn, hs)
+        super(SearchBackgroundUpdateStore, self).__init__(db_conn, hs)
 
         if not hs.config.enable_search:
             return
@@ -289,29 +289,6 @@ class SearchStore(BackgroundUpdateStore):
 
         return num_rows
 
-    def store_event_search_txn(self, txn, event, key, value):
-        """Add event to the search table
-
-        Args:
-            txn (cursor):
-            event (EventBase):
-            key (str):
-            value (str):
-        """
-        self.store_search_entries_txn(
-            txn,
-            (
-                SearchEntry(
-                    key=key,
-                    value=value,
-                    event_id=event.event_id,
-                    room_id=event.room_id,
-                    stream_ordering=event.internal_metadata.stream_ordering,
-                    origin_server_ts=event.origin_server_ts,
-                ),
-            ),
-        )
-
     def store_search_entries_txn(self, txn, entries):
         """Add entries to the search table
 
@@ -358,6 +335,34 @@ class SearchStore(BackgroundUpdateStore):
             # This should be unreachable.
             raise Exception("Unrecognized database engine")
 
+
+class SearchStore(SearchBackgroundUpdateStore):
+    def __init__(self, db_conn, hs):
+        super(SearchStore, self).__init__(db_conn, hs)
+
+    def store_event_search_txn(self, txn, event, key, value):
+        """Add event to the search table
+
+        Args:
+            txn (cursor):
+            event (EventBase):
+            key (str):
+            value (str):
+        """
+        self.store_search_entries_txn(
+            txn,
+            (
+                SearchEntry(
+                    key=key,
+                    value=value,
+                    event_id=event.event_id,
+                    room_id=event.room_id,
+                    stream_ordering=event.internal_metadata.stream_ordering,
+                    origin_server_ts=event.origin_server_ts,
+                ),
+            ),
+        )
+
     @defer.inlineCallbacks
     def search_msgs(self, room_ids, search_term, keys):
         """Performs a full text search over events with given keys.
diff --git a/synapse/storage/state.py b/synapse/storage/state.py
index 1980a87108..a941a5ae3f 100644
--- a/synapse/storage/state.py
+++ b/synapse/storage/state.py
@@ -353,8 +353,158 @@ class StateFilter(object):
         return member_filter, non_member_filter
 
 
+class StateGroupBackgroundUpdateStore(SQLBaseStore):
+    """Defines functions related to state groups needed to run the state backgroud
+    updates.
+    """
+
+    def _count_state_group_hops_txn(self, txn, state_group):
+        """Given a state group, count how many hops there are in the tree.
+
+        This is used to ensure the delta chains don't get too long.
+        """
+        if isinstance(self.database_engine, PostgresEngine):
+            sql = """
+                WITH RECURSIVE state(state_group) AS (
+                    VALUES(?::bigint)
+                    UNION ALL
+                    SELECT prev_state_group FROM state_group_edges e, state s
+                    WHERE s.state_group = e.state_group
+                )
+                SELECT count(*) FROM state;
+            """
+
+            txn.execute(sql, (state_group,))
+            row = txn.fetchone()
+            if row and row[0]:
+                return row[0]
+            else:
+                return 0
+        else:
+            # We don't use WITH RECURSIVE on sqlite3 as there are distributions
+            # that ship with an sqlite3 version that doesn't support it (e.g. wheezy)
+            next_group = state_group
+            count = 0
+
+            while next_group:
+                next_group = self._simple_select_one_onecol_txn(
+                    txn,
+                    table="state_group_edges",
+                    keyvalues={"state_group": next_group},
+                    retcol="prev_state_group",
+                    allow_none=True,
+                )
+                if next_group:
+                    count += 1
+
+            return count
+
+    def _get_state_groups_from_groups_txn(
+        self, txn, groups, state_filter=StateFilter.all()
+    ):
+        results = {group: {} for group in groups}
+
+        where_clause, where_args = state_filter.make_sql_filter_clause()
+
+        # Unless the filter clause is empty, we're going to append it after an
+        # existing where clause
+        if where_clause:
+            where_clause = " AND (%s)" % (where_clause,)
+
+        if isinstance(self.database_engine, PostgresEngine):
+            # Temporarily disable sequential scans in this transaction. This is
+            # a temporary hack until we can add the right indices in
+            txn.execute("SET LOCAL enable_seqscan=off")
+
+            # The below query walks the state_group tree so that the "state"
+            # table includes all state_groups in the tree. It then joins
+            # against `state_groups_state` to fetch the latest state.
+            # It assumes that previous state groups are always numerically
+            # lesser.
+            # The PARTITION is used to get the event_id in the greatest state
+            # group for the given type, state_key.
+            # This may return multiple rows per (type, state_key), but last_value
+            # should be the same.
+            sql = """
+                WITH RECURSIVE state(state_group) AS (
+                    VALUES(?::bigint)
+                    UNION ALL
+                    SELECT prev_state_group FROM state_group_edges e, state s
+                    WHERE s.state_group = e.state_group
+                )
+                SELECT DISTINCT type, state_key, last_value(event_id) OVER (
+                    PARTITION BY type, state_key ORDER BY state_group ASC
+                    ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
+                ) AS event_id FROM state_groups_state
+                WHERE state_group IN (
+                    SELECT state_group FROM state
+                )
+            """
+
+            for group in groups:
+                args = [group]
+                args.extend(where_args)
+
+                txn.execute(sql + where_clause, args)
+                for row in txn:
+                    typ, state_key, event_id = row
+                    key = (typ, state_key)
+                    results[group][key] = event_id
+        else:
+            max_entries_returned = state_filter.max_entries_returned()
+
+            # We don't use WITH RECURSIVE on sqlite3 as there are distributions
+            # that ship with an sqlite3 version that doesn't support it (e.g. wheezy)
+            for group in groups:
+                next_group = group
+
+                while next_group:
+                    # We did this before by getting the list of group ids, and
+                    # then passing that list to sqlite to get latest event for
+                    # each (type, state_key). However, that was terribly slow
+                    # without the right indices (which we can't add until
+                    # after we finish deduping state, which requires this func)
+                    args = [next_group]
+                    args.extend(where_args)
+
+                    txn.execute(
+                        "SELECT type, state_key, event_id FROM state_groups_state"
+                        " WHERE state_group = ? " + where_clause,
+                        args,
+                    )
+                    results[group].update(
+                        ((typ, state_key), event_id)
+                        for typ, state_key, event_id in txn
+                        if (typ, state_key) not in results[group]
+                    )
+
+                    # If the number of entries in the (type,state_key)->event_id dict
+                    # matches the number of (type,state_keys) types we were searching
+                    # for, then we must have found them all, so no need to go walk
+                    # further down the tree... UNLESS our types filter contained
+                    # wildcards (i.e. Nones) in which case we have to do an exhaustive
+                    # search
+                    if (
+                        max_entries_returned is not None
+                        and len(results[group]) == max_entries_returned
+                    ):
+                        break
+
+                    next_group = self._simple_select_one_onecol_txn(
+                        txn,
+                        table="state_group_edges",
+                        keyvalues={"state_group": next_group},
+                        retcol="prev_state_group",
+                        allow_none=True,
+                    )
+
+        return results
+
+
 # this inherits from EventsWorkerStore because it calls self.get_events
-class StateGroupWorkerStore(EventsWorkerStore, SQLBaseStore):
+class StateGroupWorkerStore(
+    EventsWorkerStore, StateGroupBackgroundUpdateStore, SQLBaseStore
+):
     """The parts of StateGroupStore that can be called from workers.
     """
 
@@ -694,107 +844,6 @@ class StateGroupWorkerStore(EventsWorkerStore, SQLBaseStore):
 
         return results
 
-    def _get_state_groups_from_groups_txn(
-        self, txn, groups, state_filter=StateFilter.all()
-    ):
-        results = {group: {} for group in groups}
-
-        where_clause, where_args = state_filter.make_sql_filter_clause()
-
-        # Unless the filter clause is empty, we're going to append it after an
-        # existing where clause
-        if where_clause:
-            where_clause = " AND (%s)" % (where_clause,)
-
-        if isinstance(self.database_engine, PostgresEngine):
-            # Temporarily disable sequential scans in this transaction. This is
-            # a temporary hack until we can add the right indices in
-            txn.execute("SET LOCAL enable_seqscan=off")
-
-            # The below query walks the state_group tree so that the "state"
-            # table includes all state_groups in the tree. It then joins
-            # against `state_groups_state` to fetch the latest state.
-            # It assumes that previous state groups are always numerically
-            # lesser.
-            # The PARTITION is used to get the event_id in the greatest state
-            # group for the given type, state_key.
-            # This may return multiple rows per (type, state_key), but last_value
-            # should be the same.
-            sql = """
-                WITH RECURSIVE state(state_group) AS (
-                    VALUES(?::bigint)
-                    UNION ALL
-                    SELECT prev_state_group FROM state_group_edges e, state s
-                    WHERE s.state_group = e.state_group
-                )
-                SELECT DISTINCT type, state_key, last_value(event_id) OVER (
-                    PARTITION BY type, state_key ORDER BY state_group ASC
-                    ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
-                ) AS event_id FROM state_groups_state
-                WHERE state_group IN (
-                    SELECT state_group FROM state
-                )
-            """
-
-            for group in groups:
-                args = [group]
-                args.extend(where_args)
-
-                txn.execute(sql + where_clause, args)
-                for row in txn:
-                    typ, state_key, event_id = row
-                    key = (typ, state_key)
-                    results[group][key] = event_id
-        else:
-            max_entries_returned = state_filter.max_entries_returned()
-
-            # We don't use WITH RECURSIVE on sqlite3 as there are distributions
-            # that ship with an sqlite3 version that doesn't support it (e.g. wheezy)
-            for group in groups:
-                next_group = group
-
-                while next_group:
-                    # We did this before by getting the list of group ids, and
-                    # then passing that list to sqlite to get latest event for
-                    # each (type, state_key). However, that was terribly slow
-                    # without the right indices (which we can't add until
-                    # after we finish deduping state, which requires this func)
-                    args = [next_group]
-                    args.extend(where_args)
-
-                    txn.execute(
-                        "SELECT type, state_key, event_id FROM state_groups_state"
-                        " WHERE state_group = ? " + where_clause,
-                        args,
-                    )
-                    results[group].update(
-                        ((typ, state_key), event_id)
-                        for typ, state_key, event_id in txn
-                        if (typ, state_key) not in results[group]
-                    )
-
-                    # If the number of entries in the (type,state_key)->event_id dict
-                    # matches the number of (type,state_keys) types we were searching
-                    # for, then we must have found them all, so no need to go walk
-                    # further down the tree... UNLESS our types filter contained
-                    # wildcards (i.e. Nones) in which case we have to do an exhaustive
-                    # search
-                    if (
-                        max_entries_returned is not None
-                        and len(results[group]) == max_entries_returned
-                    ):
-                        break
-
-                    next_group = self._simple_select_one_onecol_txn(
-                        txn,
-                        table="state_group_edges",
-                        keyvalues={"state_group": next_group},
-                        retcol="prev_state_group",
-                        allow_none=True,
-                    )
-
-        return results
-
     @defer.inlineCallbacks
     def get_state_for_events(self, event_ids, state_filter=StateFilter.all()):
         """Given a list of event_ids and type tuples, return a list of state
@@ -1238,66 +1287,10 @@ class StateGroupWorkerStore(EventsWorkerStore, SQLBaseStore):
 
         return self.runInteraction("store_state_group", _store_state_group_txn)
 
-    def _count_state_group_hops_txn(self, txn, state_group):
-        """Given a state group, count how many hops there are in the tree.
-
-        This is used to ensure the delta chains don't get too long.
-        """
-        if isinstance(self.database_engine, PostgresEngine):
-            sql = """
-                WITH RECURSIVE state(state_group) AS (
-                    VALUES(?::bigint)
-                    UNION ALL
-                    SELECT prev_state_group FROM state_group_edges e, state s
-                    WHERE s.state_group = e.state_group
-                )
-                SELECT count(*) FROM state;
-            """
-
-            txn.execute(sql, (state_group,))
-            row = txn.fetchone()
-            if row and row[0]:
-                return row[0]
-            else:
-                return 0
-        else:
-            # We don't use WITH RECURSIVE on sqlite3 as there are distributions
-            # that ship with an sqlite3 version that doesn't support it (e.g. wheezy)
-            next_group = state_group
-            count = 0
-
-            while next_group:
-                next_group = self._simple_select_one_onecol_txn(
-                    txn,
-                    table="state_group_edges",
-                    keyvalues={"state_group": next_group},
-                    retcol="prev_state_group",
-                    allow_none=True,
-                )
-                if next_group:
-                    count += 1
-
-            return count
-
-
-class StateStore(StateGroupWorkerStore, BackgroundUpdateStore):
-    """ Keeps track of the state at a given event.
-
-    This is done by the concept of `state groups`. Every event is a assigned
-    a state group (identified by an arbitrary string), which references a
-    collection of state events. The current state of an event is then the
-    collection of state events referenced by the event's state group.
 
-    Hence, every change in the current state causes a new state group to be
-    generated. However, if no change happens (e.g., if we get a message event
-    with only one parent it inherits the state group from its parent.)
-
-    There are three tables:
-      * `state_groups`: Stores group name, first event with in the group and
-        room id.
-      * `event_to_state_groups`: Maps events to state groups.
-      * `state_groups_state`: Maps state group to state events.
-    """
+class StateBackgroundUpdateStore(
+    StateGroupBackgroundUpdateStore, BackgroundUpdateStore
+):
 
     STATE_GROUP_DEDUPLICATION_UPDATE_NAME = "state_group_state_deduplication"
     STATE_GROUP_INDEX_UPDATE_NAME = "state_group_state_type_index"
@@ -1305,7 +1298,7 @@ class StateStore(StateGroupWorkerStore, BackgroundUpdateStore):
     EVENT_STATE_GROUP_INDEX_UPDATE_NAME = "event_to_state_groups_sg_index"
 
     def __init__(self, db_conn, hs):
-        super(StateStore, self).__init__(db_conn, hs)
+        super(StateBackgroundUpdateStore, self).__init__(db_conn, hs)
         self.register_background_update_handler(
             self.STATE_GROUP_DEDUPLICATION_UPDATE_NAME,
             self._background_deduplicate_state,
@@ -1327,34 +1320,6 @@ class StateStore(StateGroupWorkerStore, BackgroundUpdateStore):
             columns=["state_group"],
         )
 
-    def _store_event_state_mappings_txn(self, txn, events_and_contexts):
-        state_groups = {}
-        for event, context in events_and_contexts:
-            if event.internal_metadata.is_outlier():
-                continue
-
-            # if the event was rejected, just give it the same state as its
-            # predecessor.
-            if context.rejected:
-                state_groups[event.event_id] = context.prev_group
-                continue
-
-            state_groups[event.event_id] = context.state_group
-
-        self._simple_insert_many_txn(
-            txn,
-            table="event_to_state_groups",
-            values=[
-                {"state_group": state_group_id, "event_id": event_id}
-                for event_id, state_group_id in iteritems(state_groups)
-            ],
-        )
-
-        for event_id, state_group_id in iteritems(state_groups):
-            txn.call_after(
-                self._get_state_group_for_event.prefill, (event_id,), state_group_id
-            )
-
     @defer.inlineCallbacks
     def _background_deduplicate_state(self, progress, batch_size):
         """This background update will slowly deduplicate state by reencoding
@@ -1527,3 +1492,54 @@ class StateStore(StateGroupWorkerStore, BackgroundUpdateStore):
         yield self._end_background_update(self.STATE_GROUP_INDEX_UPDATE_NAME)
 
         return 1
+
+
+class StateStore(StateGroupWorkerStore, StateBackgroundUpdateStore):
+    """ Keeps track of the state at a given event.
+
+    This is done by the concept of `state groups`. Every event is a assigned
+    a state group (identified by an arbitrary string), which references a
+    collection of state events. The current state of an event is then the
+    collection of state events referenced by the event's state group.
+
+    Hence, every change in the current state causes a new state group to be
+    generated. However, if no change happens (e.g., if we get a message event
+    with only one parent it inherits the state group from its parent.)
+
+    There are three tables:
+      * `state_groups`: Stores group name, first event with in the group and
+        room id.
+      * `event_to_state_groups`: Maps events to state groups.
+      * `state_groups_state`: Maps state group to state events.
+    """
+
+    def __init__(self, db_conn, hs):
+        super(StateStore, self).__init__(db_conn, hs)
+
+    def _store_event_state_mappings_txn(self, txn, events_and_contexts):
+        state_groups = {}
+        for event, context in events_and_contexts:
+            if event.internal_metadata.is_outlier():
+                continue
+
+            # if the event was rejected, just give it the same state as its
+            # predecessor.
+            if context.rejected:
+                state_groups[event.event_id] = context.prev_group
+                continue
+
+            state_groups[event.event_id] = context.state_group
+
+        self._simple_insert_many_txn(
+            txn,
+            table="event_to_state_groups",
+            values=[
+                {"state_group": state_group_id, "event_id": event_id}
+                for event_id, state_group_id in iteritems(state_groups)
+            ],
+        )
+
+        for event_id, state_group_id in iteritems(state_groups):
+            txn.call_after(
+                self._get_state_group_for_event.prefill, (event_id,), state_group_id
+            )
diff --git a/synapse/storage/stats.py b/synapse/storage/stats.py
index 09190d684e..7c224cd3d9 100644
--- a/synapse/storage/stats.py
+++ b/synapse/storage/stats.py
@@ -332,6 +332,9 @@ class StatsStore(StateDeltasStore):
         def _bulk_update_stats_delta_txn(txn):
             for stats_type, stats_updates in updates.items():
                 for stats_id, fields in stats_updates.items():
+                    logger.info(
+                        "Updating %s stats for %s: %s", stats_type, stats_id, fields
+                    )
                     self._update_stats_delta_txn(
                         txn,
                         ts=ts,
diff --git a/synapse/storage/user_directory.py b/synapse/storage/user_directory.py
index b5188d9bee..1b1e4751b9 100644
--- a/synapse/storage/user_directory.py
+++ b/synapse/storage/user_directory.py
@@ -32,14 +32,14 @@ logger = logging.getLogger(__name__)
 TEMP_TABLE = "_temp_populate_user_directory"
 
 
-class UserDirectoryStore(StateDeltasStore, BackgroundUpdateStore):
+class UserDirectoryBackgroundUpdateStore(StateDeltasStore, BackgroundUpdateStore):
 
     # How many records do we calculate before sending it to
     # add_users_who_share_private_rooms?
     SHARE_PRIVATE_WORKING_SET = 500
 
     def __init__(self, db_conn, hs):
-        super(UserDirectoryStore, self).__init__(db_conn, hs)
+        super(UserDirectoryBackgroundUpdateStore, self).__init__(db_conn, hs)
 
         self.server_name = hs.hostname
 
@@ -452,55 +452,6 @@ class UserDirectoryStore(StateDeltasStore, BackgroundUpdateStore):
             "update_profile_in_user_dir", _update_profile_in_user_dir_txn
         )
 
-    def remove_from_user_dir(self, user_id):
-        def _remove_from_user_dir_txn(txn):
-            self._simple_delete_txn(
-                txn, table="user_directory", keyvalues={"user_id": user_id}
-            )
-            self._simple_delete_txn(
-                txn, table="user_directory_search", keyvalues={"user_id": user_id}
-            )
-            self._simple_delete_txn(
-                txn, table="users_in_public_rooms", keyvalues={"user_id": user_id}
-            )
-            self._simple_delete_txn(
-                txn,
-                table="users_who_share_private_rooms",
-                keyvalues={"user_id": user_id},
-            )
-            self._simple_delete_txn(
-                txn,
-                table="users_who_share_private_rooms",
-                keyvalues={"other_user_id": user_id},
-            )
-            txn.call_after(self.get_user_in_directory.invalidate, (user_id,))
-
-        return self.runInteraction("remove_from_user_dir", _remove_from_user_dir_txn)
-
-    @defer.inlineCallbacks
-    def get_users_in_dir_due_to_room(self, room_id):
-        """Get all user_ids that are in the room directory because they're
-        in the given room_id
-        """
-        user_ids_share_pub = yield self._simple_select_onecol(
-            table="users_in_public_rooms",
-            keyvalues={"room_id": room_id},
-            retcol="user_id",
-            desc="get_users_in_dir_due_to_room",
-        )
-
-        user_ids_share_priv = yield self._simple_select_onecol(
-            table="users_who_share_private_rooms",
-            keyvalues={"room_id": room_id},
-            retcol="other_user_id",
-            desc="get_users_in_dir_due_to_room",
-        )
-
-        user_ids = set(user_ids_share_pub)
-        user_ids.update(user_ids_share_priv)
-
-        return user_ids
-
     def add_users_who_share_private_room(self, room_id, user_id_tuples):
         """Insert entries into the users_who_share_private_rooms table. The first
         user should be a local user.
@@ -551,6 +502,98 @@ class UserDirectoryStore(StateDeltasStore, BackgroundUpdateStore):
             "add_users_in_public_rooms", _add_users_in_public_rooms_txn
         )
 
+    def delete_all_from_user_dir(self):
+        """Delete the entire user directory
+        """
+
+        def _delete_all_from_user_dir_txn(txn):
+            txn.execute("DELETE FROM user_directory")
+            txn.execute("DELETE FROM user_directory_search")
+            txn.execute("DELETE FROM users_in_public_rooms")
+            txn.execute("DELETE FROM users_who_share_private_rooms")
+            txn.call_after(self.get_user_in_directory.invalidate_all)
+
+        return self.runInteraction(
+            "delete_all_from_user_dir", _delete_all_from_user_dir_txn
+        )
+
+    @cached()
+    def get_user_in_directory(self, user_id):
+        return self._simple_select_one(
+            table="user_directory",
+            keyvalues={"user_id": user_id},
+            retcols=("display_name", "avatar_url"),
+            allow_none=True,
+            desc="get_user_in_directory",
+        )
+
+    def update_user_directory_stream_pos(self, stream_id):
+        return self._simple_update_one(
+            table="user_directory_stream_pos",
+            keyvalues={},
+            updatevalues={"stream_id": stream_id},
+            desc="update_user_directory_stream_pos",
+        )
+
+
+class UserDirectoryStore(UserDirectoryBackgroundUpdateStore):
+
+    # How many records do we calculate before sending it to
+    # add_users_who_share_private_rooms?
+    SHARE_PRIVATE_WORKING_SET = 500
+
+    def __init__(self, db_conn, hs):
+        super(UserDirectoryStore, self).__init__(db_conn, hs)
+
+    def remove_from_user_dir(self, user_id):
+        def _remove_from_user_dir_txn(txn):
+            self._simple_delete_txn(
+                txn, table="user_directory", keyvalues={"user_id": user_id}
+            )
+            self._simple_delete_txn(
+                txn, table="user_directory_search", keyvalues={"user_id": user_id}
+            )
+            self._simple_delete_txn(
+                txn, table="users_in_public_rooms", keyvalues={"user_id": user_id}
+            )
+            self._simple_delete_txn(
+                txn,
+                table="users_who_share_private_rooms",
+                keyvalues={"user_id": user_id},
+            )
+            self._simple_delete_txn(
+                txn,
+                table="users_who_share_private_rooms",
+                keyvalues={"other_user_id": user_id},
+            )
+            txn.call_after(self.get_user_in_directory.invalidate, (user_id,))
+
+        return self.runInteraction("remove_from_user_dir", _remove_from_user_dir_txn)
+
+    @defer.inlineCallbacks
+    def get_users_in_dir_due_to_room(self, room_id):
+        """Get all user_ids that are in the room directory because they're
+        in the given room_id
+        """
+        user_ids_share_pub = yield self._simple_select_onecol(
+            table="users_in_public_rooms",
+            keyvalues={"room_id": room_id},
+            retcol="user_id",
+            desc="get_users_in_dir_due_to_room",
+        )
+
+        user_ids_share_priv = yield self._simple_select_onecol(
+            table="users_who_share_private_rooms",
+            keyvalues={"room_id": room_id},
+            retcol="other_user_id",
+            desc="get_users_in_dir_due_to_room",
+        )
+
+        user_ids = set(user_ids_share_pub)
+        user_ids.update(user_ids_share_priv)
+
+        return user_ids
+
     def remove_user_who_share_room(self, user_id, room_id):
         """
         Deletes entries in the users_who_share_*_rooms table. The first
@@ -637,31 +680,6 @@ class UserDirectoryStore(StateDeltasStore, BackgroundUpdateStore):
 
         return [room_id for room_id, in rows]
 
-    def delete_all_from_user_dir(self):
-        """Delete the entire user directory
-        """
-
-        def _delete_all_from_user_dir_txn(txn):
-            txn.execute("DELETE FROM user_directory")
-            txn.execute("DELETE FROM user_directory_search")
-            txn.execute("DELETE FROM users_in_public_rooms")
-            txn.execute("DELETE FROM users_who_share_private_rooms")
-            txn.call_after(self.get_user_in_directory.invalidate_all)
-
-        return self.runInteraction(
-            "delete_all_from_user_dir", _delete_all_from_user_dir_txn
-        )
-
-    @cached()
-    def get_user_in_directory(self, user_id):
-        return self._simple_select_one(
-            table="user_directory",
-            keyvalues={"user_id": user_id},
-            retcols=("display_name", "avatar_url"),
-            allow_none=True,
-            desc="get_user_in_directory",
-        )
-
     def get_user_directory_stream_pos(self):
         return self._simple_select_one_onecol(
             table="user_directory_stream_pos",
@@ -670,14 +688,6 @@ class UserDirectoryStore(StateDeltasStore, BackgroundUpdateStore):
             desc="get_user_directory_stream_pos",
         )
 
-    def update_user_directory_stream_pos(self, stream_id):
-        return self._simple_update_one(
-            table="user_directory_stream_pos",
-            keyvalues={},
-            updatevalues={"stream_id": stream_id},
-            desc="update_user_directory_stream_pos",
-        )
-
     @defer.inlineCallbacks
     def search_user_dir(self, user_id, search_term, limit):
         """Searches for users in directory
diff --git a/synapse/types.py b/synapse/types.py
index 51eadb6ad4..8f79797f17 100644
--- a/synapse/types.py
+++ b/synapse/types.py
@@ -318,6 +318,7 @@ class StreamToken(
     )
 ):
     _SEPARATOR = "_"
+    START = None  # type: StreamToken
 
     @classmethod
     def from_string(cls, string):
@@ -402,7 +403,7 @@ class RoomStreamToken(namedtuple("_StreamToken", "topological stream")):
     followed by the "stream_ordering" id of the event it comes after.
     """
 
-    __slots__ = []
+    __slots__ = []  # type: list
 
     @classmethod
     def parse(cls, string):
diff --git a/synapse/util/async_helpers.py b/synapse/util/async_helpers.py
index f1c46836b1..0d3bdd88ce 100644
--- a/synapse/util/async_helpers.py
+++ b/synapse/util/async_helpers.py
@@ -13,9 +13,11 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+
 import collections
 import logging
 from contextlib import contextmanager
+from typing import Dict, Sequence, Set, Union
 
 from six.moves import range
 
@@ -213,7 +215,9 @@ class Linearizer(object):
         # the first element is the number of things executing, and
         # the second element is an OrderedDict, where the keys are deferreds for the
         # things blocked from executing.
-        self.key_to_defer = {}
+        self.key_to_defer = (
+            {}
+        )  # type: Dict[str, Sequence[Union[int, Dict[defer.Deferred, int]]]]
 
     def queue(self, key):
         # we avoid doing defer.inlineCallbacks here, so that cancellation works correctly.
@@ -340,10 +344,10 @@ class ReadWriteLock(object):
 
     def __init__(self):
         # Latest readers queued
-        self.key_to_current_readers = {}
+        self.key_to_current_readers = {}  # type: Dict[str, Set[defer.Deferred]]
 
         # Latest writer queued
-        self.key_to_current_writer = {}
+        self.key_to_current_writer = {}  # type: Dict[str, defer.Deferred]
 
     @defer.inlineCallbacks
     def read(self, key):
diff --git a/synapse/util/caches/__init__.py b/synapse/util/caches/__init__.py
index b50e3503f0..43fd65d693 100644
--- a/synapse/util/caches/__init__.py
+++ b/synapse/util/caches/__init__.py
@@ -16,6 +16,7 @@
 
 import logging
 import os
+from typing import Dict
 
 import six
 from six.moves import intern
@@ -37,7 +38,7 @@ def get_cache_factor_for(cache_name):
 
 
 caches_by_name = {}
-collectors_by_name = {}
+collectors_by_name = {}  # type: Dict
 
 cache_size = Gauge("synapse_util_caches_cache:size", "", ["name"])
 cache_hits = Gauge("synapse_util_caches_cache:hits", "", ["name"])
diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index 43f66ec4be..5ac2530a6a 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -18,10 +18,12 @@ import inspect
 import logging
 import threading
 from collections import namedtuple
+from typing import Any, cast
 
 from six import itervalues
 
 from prometheus_client import Gauge
+from typing_extensions import Protocol
 
 from twisted.internet import defer
 
@@ -37,6 +39,18 @@ from . import register_cache
 logger = logging.getLogger(__name__)
 
 
+class _CachedFunction(Protocol):
+    invalidate = None  # type: Any
+    invalidate_all = None  # type: Any
+    invalidate_many = None  # type: Any
+    prefill = None  # type: Any
+    cache = None  # type: Any
+    num_args = None  # type: Any
+
+    def __name__(self):
+        ...
+
+
 cache_pending_metric = Gauge(
     "synapse_util_caches_cache_pending",
     "Number of lookups currently pending for this cache",
@@ -245,7 +259,9 @@ class Cache(object):
 
 
 class _CacheDescriptorBase(object):
-    def __init__(self, orig, num_args, inlineCallbacks, cache_context=False):
+    def __init__(
+        self, orig: _CachedFunction, num_args, inlineCallbacks, cache_context=False
+    ):
         self.orig = orig
 
         if inlineCallbacks:
@@ -404,7 +420,7 @@ class CacheDescriptor(_CacheDescriptorBase):
                 return tuple(get_cache_key_gen(args, kwargs))
 
         @functools.wraps(self.orig)
-        def wrapped(*args, **kwargs):
+        def _wrapped(*args, **kwargs):
             # If we're passed a cache_context then we'll want to call its invalidate()
             # whenever we are invalidated
             invalidate_callback = kwargs.pop("on_invalidate", None)
@@ -440,6 +456,8 @@ class CacheDescriptor(_CacheDescriptorBase):
 
             return make_deferred_yieldable(observer)
 
+        wrapped = cast(_CachedFunction, _wrapped)
+
         if self.num_args == 1:
             wrapped.invalidate = lambda key: cache.invalidate(key[0])
             wrapped.prefill = lambda key, val: cache.prefill(key[0], val)
diff --git a/synapse/util/caches/treecache.py b/synapse/util/caches/treecache.py
index 9a72218d85..2ea4e4e911 100644
--- a/synapse/util/caches/treecache.py
+++ b/synapse/util/caches/treecache.py
@@ -1,3 +1,5 @@
+from typing import Dict
+
 from six import itervalues
 
 SENTINEL = object()
@@ -12,7 +14,7 @@ class TreeCache(object):
 
     def __init__(self):
         self.size = 0
-        self.root = {}
+        self.root = {}  # type: Dict
 
     def __setitem__(self, key, value):
         return self.set(key, value)
diff --git a/synapse/util/metrics.py b/synapse/util/metrics.py
index 0910930c21..4b1bcdf23c 100644
--- a/synapse/util/metrics.py
+++ b/synapse/util/metrics.py
@@ -60,12 +60,14 @@ in_flight = InFlightGauge(
 )
 
 
-def measure_func(name):
+def measure_func(name=None):
     def wrapper(func):
+        block_name = func.__name__ if name is None else name
+
         @wraps(func)
         @defer.inlineCallbacks
         def measured_func(self, *args, **kwargs):
-            with Measure(self.clock, name):
+            with Measure(self.clock, block_name):
                 r = yield func(self, *args, **kwargs)
             return r
 
diff --git a/synapse/util/module_loader.py b/synapse/util/module_loader.py
index 7ff7eb1e4d..2705cbe5f8 100644
--- a/synapse/util/module_loader.py
+++ b/synapse/util/module_loader.py
@@ -54,5 +54,5 @@ def load_python_module(location: str):
     if spec is None:
         raise Exception("Unable to load module at %s" % (location,))
     mod = importlib.util.module_from_spec(spec)
-    spec.loader.exec_module(mod)
+    spec.loader.exec_module(mod)  # type: ignore
     return mod
diff --git a/synapse/util/retryutils.py b/synapse/util/retryutils.py
index a5f2fbef5c..af69587196 100644
--- a/synapse/util/retryutils.py
+++ b/synapse/util/retryutils.py
@@ -29,7 +29,7 @@ MIN_RETRY_INTERVAL = 10 * 60 * 1000
 RETRY_MULTIPLIER = 5
 
 # a cap on the backoff. (Essentially none)
-MAX_RETRY_INTERVAL = 2 ** 63
+MAX_RETRY_INTERVAL = 2 ** 62
 
 
 class NotRetryingDestination(Exception):