Merge branch 'develop' into rav/fix_attribute_mapping

28 files changed, 1649 insertions, 552 deletions

diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index 489ce82fae..abe16334ec 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -1395,14 +1395,22 @@ class SQLBaseStore(object):
         """
         txn.call_after(self._invalidate_state_caches, room_id, members_changed)
 
-        # We need to be careful that the size of the `members_changed` list
-        # isn't so large that it causes problems sending over replication, so we
-        # send them in chunks.
-        # Max line length is 16K, and max user ID length is 255, so 50 should
-        # be safe.
-        for chunk in batch_iter(members_changed, 50):
-            keys = itertools.chain([room_id], chunk)
-            self._send_invalidation_to_replication(txn, _CURRENT_STATE_CACHE_NAME, keys)
+        if members_changed:
+            # We need to be careful that the size of the `members_changed` list
+            # isn't so large that it causes problems sending over replication, so we
+            # send them in chunks.
+            # Max line length is 16K, and max user ID length is 255, so 50 should
+            # be safe.
+            for chunk in batch_iter(members_changed, 50):
+                keys = itertools.chain([room_id], chunk)
+                self._send_invalidation_to_replication(
+                    txn, _CURRENT_STATE_CACHE_NAME, keys
+                )
+        else:
+            # if no members changed, we still need to invalidate the other caches.
+            self._send_invalidation_to_replication(
+                txn, _CURRENT_STATE_CACHE_NAME, [room_id]
+            )
 
     def _invalidate_state_caches(self, room_id, members_changed):
         """Invalidates caches that are based on the current state, but does
diff --git a/synapse/storage/account_data.py b/synapse/storage/account_data.py
index 9fa5b4f3d6..6afbfc0d74 100644
--- a/synapse/storage/account_data.py
+++ b/synapse/storage/account_data.py
@@ -90,7 +90,7 @@ class AccountDataWorkerStore(SQLBaseStore):
                 room_data = by_room.setdefault(row["room_id"], {})
                 room_data[row["account_data_type"]] = json.loads(row["content"])
 
-            return (global_account_data, by_room)
+            return global_account_data, by_room
 
         return self.runInteraction(
             "get_account_data_for_user", get_account_data_for_user_txn
@@ -205,7 +205,7 @@ class AccountDataWorkerStore(SQLBaseStore):
             )
             txn.execute(sql, (last_room_id, current_id, limit))
             room_results = txn.fetchall()
-            return (global_results, room_results)
+            return global_results, room_results
 
         return self.runInteraction(
             "get_all_updated_account_data_txn", get_updated_account_data_txn
@@ -244,13 +244,13 @@ class AccountDataWorkerStore(SQLBaseStore):
                 room_account_data = account_data_by_room.setdefault(row[0], {})
                 room_account_data[row[1]] = json.loads(row[2])
 
-            return (global_account_data, account_data_by_room)
+            return global_account_data, account_data_by_room
 
         changed = self._account_data_stream_cache.has_entity_changed(
             user_id, int(stream_id)
         )
         if not changed:
-            return ({}, {})
+            return {}, {}
 
         return self.runInteraction(
             "get_updated_account_data_for_user", get_updated_account_data_for_user_txn
diff --git a/synapse/storage/appservice.py b/synapse/storage/appservice.py
index 05d9c05c3f..435b2acd4d 100644
--- a/synapse/storage/appservice.py
+++ b/synapse/storage/appservice.py
@@ -165,7 +165,6 @@ class ApplicationServiceTransactionWorkerStore(
         )
         if result:
             return result.get("state")
-            return
         return None
 
     def set_appservice_state(self, service, state):
@@ -358,7 +357,7 @@ class ApplicationServiceTransactionWorkerStore(
 
         events = yield self.get_events_as_list(event_ids)
 
-        return (upper_bound, events)
+        return upper_bound, events
 
 
 class ApplicationServiceTransactionStore(ApplicationServiceTransactionWorkerStore):
diff --git a/synapse/storage/deviceinbox.py b/synapse/storage/deviceinbox.py
index 79bb0ea46d..6b7458304e 100644
--- a/synapse/storage/deviceinbox.py
+++ b/synapse/storage/deviceinbox.py
@@ -19,6 +19,7 @@ from canonicaljson import json
 
 from twisted.internet import defer
 
+from synapse.logging.opentracing import log_kv, set_tag, trace
 from synapse.storage._base import SQLBaseStore
 from synapse.storage.background_updates import BackgroundUpdateStore
 from synapse.util.caches.expiringcache import ExpiringCache
@@ -66,12 +67,13 @@ class DeviceInboxWorkerStore(SQLBaseStore):
                 messages.append(json.loads(row[1]))
             if len(messages) < limit:
                 stream_pos = current_stream_id
-            return (messages, stream_pos)
+            return messages, stream_pos
 
         return self.runInteraction(
             "get_new_messages_for_device", get_new_messages_for_device_txn
         )
 
+    @trace
     @defer.inlineCallbacks
     def delete_messages_for_device(self, user_id, device_id, up_to_stream_id):
         """
@@ -87,11 +89,15 @@ class DeviceInboxWorkerStore(SQLBaseStore):
         last_deleted_stream_id = self._last_device_delete_cache.get(
             (user_id, device_id), None
         )
+
+        set_tag("last_deleted_stream_id", last_deleted_stream_id)
+
         if last_deleted_stream_id:
             has_changed = self._device_inbox_stream_cache.has_entity_changed(
                 user_id, last_deleted_stream_id
             )
             if not has_changed:
+                log_kv({"message": "No changes in cache since last check"})
                 return 0
 
         def delete_messages_for_device_txn(txn):
@@ -107,6 +113,10 @@ class DeviceInboxWorkerStore(SQLBaseStore):
             "delete_messages_for_device", delete_messages_for_device_txn
         )
 
+        log_kv(
+            {"message": "deleted {} messages for device".format(count), "count": count}
+        )
+
         # Update the cache, ensuring that we only ever increase the value
         last_deleted_stream_id = self._last_device_delete_cache.get(
             (user_id, device_id), 0
@@ -117,6 +127,7 @@ class DeviceInboxWorkerStore(SQLBaseStore):
 
         return count
 
+    @trace
     def get_new_device_msgs_for_remote(
         self, destination, last_stream_id, current_stream_id, limit
     ):
@@ -132,16 +143,23 @@ class DeviceInboxWorkerStore(SQLBaseStore):
                 in the stream the messages got to.
         """
 
+        set_tag("destination", destination)
+        set_tag("last_stream_id", last_stream_id)
+        set_tag("current_stream_id", current_stream_id)
+        set_tag("limit", limit)
+
         has_changed = self._device_federation_outbox_stream_cache.has_entity_changed(
             destination, last_stream_id
         )
         if not has_changed or last_stream_id == current_stream_id:
+            log_kv({"message": "No new messages in stream"})
             return defer.succeed(([], current_stream_id))
 
         if limit <= 0:
             # This can happen if we run out of room for EDUs in the transaction.
             return defer.succeed(([], last_stream_id))
 
+        @trace
         def get_new_messages_for_remote_destination_txn(txn):
             sql = (
                 "SELECT stream_id, messages_json FROM device_federation_outbox"
@@ -156,14 +174,16 @@ class DeviceInboxWorkerStore(SQLBaseStore):
                 stream_pos = row[0]
                 messages.append(json.loads(row[1]))
             if len(messages) < limit:
+                log_kv({"message": "Set stream position to current position"})
                 stream_pos = current_stream_id
-            return (messages, stream_pos)
+            return messages, stream_pos
 
         return self.runInteraction(
             "get_new_device_msgs_for_remote",
             get_new_messages_for_remote_destination_txn,
         )
 
+    @trace
     def delete_device_msgs_for_remote(self, destination, up_to_stream_id):
         """Used to delete messages when the remote destination acknowledges
         their receipt.
@@ -214,6 +234,7 @@ class DeviceInboxStore(DeviceInboxWorkerStore, BackgroundUpdateStore):
             expiry_ms=30 * 60 * 1000,
         )
 
+    @trace
     @defer.inlineCallbacks
     def add_messages_to_device_inbox(
         self, local_messages_by_user_then_device, remote_messages_by_destination
diff --git a/synapse/storage/devices.py b/synapse/storage/devices.py
index 8f72d92895..79a58df591 100644
--- a/synapse/storage/devices.py
+++ b/synapse/storage/devices.py
@@ -21,6 +21,12 @@ from canonicaljson import json
 from twisted.internet import defer
 
 from synapse.api.errors import StoreError
+from synapse.logging.opentracing import (
+    get_active_span_text_map,
+    set_tag,
+    trace,
+    whitelisted_homeserver,
+)
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.storage._base import Cache, SQLBaseStore, db_to_json
 from synapse.storage.background_updates import BackgroundUpdateStore
@@ -73,6 +79,7 @@ class DeviceWorkerStore(SQLBaseStore):
 
         return {d["device_id"]: d for d in devices}
 
+    @trace
     @defer.inlineCallbacks
     def get_devices_by_remote(self, destination, from_stream_id, limit):
         """Get stream of updates to send to remote servers
@@ -88,7 +95,7 @@ class DeviceWorkerStore(SQLBaseStore):
             destination, int(from_stream_id)
         )
         if not has_changed:
-            return (now_stream_id, [])
+            return now_stream_id, []
 
         # We retrieve n+1 devices from the list of outbound pokes where n is
         # our outbound device update limit. We then check if the very last
@@ -111,7 +118,7 @@ class DeviceWorkerStore(SQLBaseStore):
 
         # Return an empty list if there are no updates
         if not updates:
-            return (now_stream_id, [])
+            return now_stream_id, []
 
         # if we have exceeded the limit, we need to exclude any results with the
         # same stream_id as the last row.
@@ -127,8 +134,15 @@ class DeviceWorkerStore(SQLBaseStore):
         # (user_id, device_id) entries into a map, with the value being
         # the max stream_id across each set of duplicate entries
         #
-        # maps (user_id, device_id) -> stream_id
+        # maps (user_id, device_id) -> (stream_id, opentracing_context)
         # as long as their stream_id does not match that of the last row
+        #
+        # opentracing_context contains the opentracing metadata for the request
+        # that created the poke
+        #
+        # The most recent request's opentracing_context is used as the
+        # context which created the Edu.
+
         query_map = {}
         for update in updates:
             if stream_id_cutoff is not None and update[2] >= stream_id_cutoff:
@@ -136,7 +150,14 @@ class DeviceWorkerStore(SQLBaseStore):
                 break
 
             key = (update[0], update[1])
-            query_map[key] = max(query_map.get(key, 0), update[2])
+
+            update_context = update[3]
+            update_stream_id = update[2]
+
+            previous_update_stream_id, _ = query_map.get(key, (0, None))
+
+            if update_stream_id > previous_update_stream_id:
+                query_map[key] = (update_stream_id, update_context)
 
         # If we didn't find any updates with a stream_id lower than the cutoff, it
         # means that there are more than limit updates all of which have the same
@@ -147,13 +168,13 @@ class DeviceWorkerStore(SQLBaseStore):
         # skip that stream_id and return an empty list, and continue with the next
         # stream_id next time.
         if not query_map:
-            return (stream_id_cutoff, [])
+            return stream_id_cutoff, []
 
         results = yield self._get_device_update_edus_by_remote(
             destination, from_stream_id, query_map
         )
 
-        return (now_stream_id, results)
+        return now_stream_id, results
 
     def _get_devices_by_remote_txn(
         self, txn, destination, from_stream_id, now_stream_id, limit
@@ -171,7 +192,7 @@ class DeviceWorkerStore(SQLBaseStore):
             List: List of device updates
         """
         sql = """
-            SELECT user_id, device_id, stream_id FROM device_lists_outbound_pokes
+            SELECT user_id, device_id, stream_id, opentracing_context FROM device_lists_outbound_pokes
             WHERE destination = ? AND ? < stream_id AND stream_id <= ? AND sent = ?
             ORDER BY stream_id
             LIMIT ?
@@ -187,8 +208,9 @@ class DeviceWorkerStore(SQLBaseStore):
         Args:
             destination (str): The host the device updates are intended for
             from_stream_id (int): The minimum stream_id to filter updates by, exclusive
-            query_map (Dict[(str, str): int]): Dictionary mapping
-                user_id/device_id to update stream_id
+            query_map (Dict[(str, str): (int, str|None)]): Dictionary mapping
+                user_id/device_id to update stream_id and the relevent json-encoded
+                opentracing context
 
         Returns:
             List[Dict]: List of objects representing an device update EDU
@@ -210,12 +232,13 @@ class DeviceWorkerStore(SQLBaseStore):
                 destination, user_id, from_stream_id
             )
             for device_id, device in iteritems(user_devices):
-                stream_id = query_map[(user_id, device_id)]
+                stream_id, opentracing_context = query_map[(user_id, device_id)]
                 result = {
                     "user_id": user_id,
                     "device_id": device_id,
                     "prev_id": [prev_id] if prev_id else [],
                     "stream_id": stream_id,
+                    "org.matrix.opentracing_context": opentracing_context,
                 }
 
                 prev_id = stream_id
@@ -299,6 +322,7 @@ class DeviceWorkerStore(SQLBaseStore):
     def get_device_stream_token(self):
         return self._device_list_id_gen.get_current_token()
 
+    @trace
     @defer.inlineCallbacks
     def get_user_devices_from_cache(self, query_list):
         """Get the devices (and keys if any) for remote users from the cache.
@@ -330,7 +354,10 @@ class DeviceWorkerStore(SQLBaseStore):
             else:
                 results[user_id] = yield self._get_cached_devices_for_user(user_id)
 
-        return (user_ids_not_in_cache, results)
+        set_tag("in_cache", results)
+        set_tag("not_in_cache", user_ids_not_in_cache)
+
+        return user_ids_not_in_cache, results
 
     @cachedInlineCallbacks(num_args=2, tree=True)
     def _get_cached_user_device(self, user_id, device_id):
@@ -814,6 +841,8 @@ class DeviceStore(DeviceWorkerStore, BackgroundUpdateStore):
             ],
         )
 
+        context = get_active_span_text_map()
+
         self._simple_insert_many_txn(
             txn,
             table="device_lists_outbound_pokes",
@@ -825,6 +854,9 @@ class DeviceStore(DeviceWorkerStore, BackgroundUpdateStore):
                     "device_id": device_id,
                     "sent": False,
                     "ts": now,
+                    "opentracing_context": json.dumps(context)
+                    if whitelisted_homeserver(destination)
+                    else "{}",
                 }
                 for destination in hosts
                 for device_id in device_ids
diff --git a/synapse/storage/directory.py b/synapse/storage/directory.py
index e966a73f3d..eed7757ed5 100644
--- a/synapse/storage/directory.py
+++ b/synapse/storage/directory.py
@@ -47,7 +47,6 @@ class DirectoryWorkerStore(SQLBaseStore):
 
         if not room_id:
             return None
-            return
 
         servers = yield self._simple_select_onecol(
             "room_alias_servers",
@@ -58,7 +57,6 @@ class DirectoryWorkerStore(SQLBaseStore):
 
         if not servers:
             return None
-            return
 
         return RoomAliasMapping(room_id, room_alias.to_string(), servers)
 
diff --git a/synapse/storage/e2e_room_keys.py b/synapse/storage/e2e_room_keys.py
index 99128f2df7..be2fe2bab6 100644
--- a/synapse/storage/e2e_room_keys.py
+++ b/synapse/storage/e2e_room_keys.py
@@ -18,6 +18,7 @@ import json
 from twisted.internet import defer
 
 from synapse.api.errors import StoreError
+from synapse.logging.opentracing import log_kv, trace
 
 from ._base import SQLBaseStore
 
@@ -82,11 +83,11 @@ class EndToEndRoomKeyStore(SQLBaseStore):
             table="e2e_room_keys",
             keyvalues={
                 "user_id": user_id,
+                "version": version,
                 "room_id": room_id,
                 "session_id": session_id,
             },
             values={
-                "version": version,
                 "first_message_index": room_key["first_message_index"],
                 "forwarded_count": room_key["forwarded_count"],
                 "is_verified": room_key["is_verified"],
@@ -94,7 +95,16 @@ class EndToEndRoomKeyStore(SQLBaseStore):
             },
             lock=False,
         )
+        log_kv(
+            {
+                "message": "Set room key",
+                "room_id": room_id,
+                "session_id": session_id,
+                "room_key": room_key,
+            }
+        )
 
+    @trace
     @defer.inlineCallbacks
     def get_e2e_room_keys(self, user_id, version, room_id=None, session_id=None):
         """Bulk get the E2E room keys for a given backup, optionally filtered to a given
@@ -153,6 +163,7 @@ class EndToEndRoomKeyStore(SQLBaseStore):
 
         return sessions
 
+    @trace
     @defer.inlineCallbacks
     def delete_e2e_room_keys(self, user_id, version, room_id=None, session_id=None):
         """Bulk delete the E2E room keys for a given backup, optionally filtered to a given
@@ -236,6 +247,7 @@ class EndToEndRoomKeyStore(SQLBaseStore):
             "get_e2e_room_keys_version_info", _get_e2e_room_keys_version_info_txn
         )
 
+    @trace
     def create_e2e_room_keys_version(self, user_id, info):
         """Atomically creates a new version of this user's e2e_room_keys store
         with the given version info.
@@ -276,6 +288,7 @@ class EndToEndRoomKeyStore(SQLBaseStore):
             "create_e2e_room_keys_version_txn", _create_e2e_room_keys_version_txn
         )
 
+    @trace
     def update_e2e_room_keys_version(self, user_id, version, info):
         """Update a given backup version
 
@@ -292,6 +305,7 @@ class EndToEndRoomKeyStore(SQLBaseStore):
             desc="update_e2e_room_keys_version",
         )
 
+    @trace
     def delete_e2e_room_keys_version(self, user_id, version=None):
         """Delete a given backup version of the user's room keys.
         Doesn't delete their actual key data.
diff --git a/synapse/storage/end_to_end_keys.py b/synapse/storage/end_to_end_keys.py
index 1e07474e70..33e3a84933 100644
--- a/synapse/storage/end_to_end_keys.py
+++ b/synapse/storage/end_to_end_keys.py
@@ -18,12 +18,14 @@ from canonicaljson import encode_canonical_json
 
 from twisted.internet import defer
 
+from synapse.logging.opentracing import log_kv, set_tag, trace
 from synapse.util.caches.descriptors import cached
 
 from ._base import SQLBaseStore, db_to_json
 
 
 class EndToEndKeyWorkerStore(SQLBaseStore):
+    @trace
     @defer.inlineCallbacks
     def get_e2e_device_keys(
         self, query_list, include_all_devices=False, include_deleted_devices=False
@@ -40,6 +42,7 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
             Dict mapping from user-id to dict mapping from device_id to
             dict containing "key_json", "device_display_name".
         """
+        set_tag("query_list", query_list)
         if not query_list:
             return {}
 
@@ -57,9 +60,13 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
 
         return results
 
+    @trace
     def _get_e2e_device_keys_txn(
         self, txn, query_list, include_all_devices=False, include_deleted_devices=False
     ):
+        set_tag("include_all_devices", include_all_devices)
+        set_tag("include_deleted_devices", include_deleted_devices)
+
         query_clauses = []
         query_params = []
 
@@ -104,6 +111,7 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
             for user_id, device_id in deleted_devices:
                 result.setdefault(user_id, {})[device_id] = None
 
+        log_kv(result)
         return result
 
     @defer.inlineCallbacks
@@ -129,8 +137,9 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
             keyvalues={"user_id": user_id, "device_id": device_id},
             desc="add_e2e_one_time_keys_check",
         )
-
-        return {(row["algorithm"], row["key_id"]): row["key_json"] for row in rows}
+        result = {(row["algorithm"], row["key_id"]): row["key_json"] for row in rows}
+        log_kv({"message": "Fetched one time keys for user", "one_time_keys": result})
+        return result
 
     @defer.inlineCallbacks
     def add_e2e_one_time_keys(self, user_id, device_id, time_now, new_keys):
@@ -146,6 +155,9 @@ class EndToEndKeyWorkerStore(SQLBaseStore):
         """
 
         def _add_e2e_one_time_keys(txn):
+            set_tag("user_id", user_id)
+            set_tag("device_id", device_id)
+            set_tag("new_keys", new_keys)
             # We are protected from race between lookup and insertion due to
             # a unique constraint. If there is a race of two calls to
             # `add_e2e_one_time_keys` then they'll conflict and we will only
@@ -202,6 +214,11 @@ class EndToEndKeyStore(EndToEndKeyWorkerStore, SQLBaseStore):
         """
 
         def _set_e2e_device_keys_txn(txn):
+            set_tag("user_id", user_id)
+            set_tag("device_id", device_id)
+            set_tag("time_now", time_now)
+            set_tag("device_keys", device_keys)
+
             old_key_json = self._simple_select_one_onecol_txn(
                 txn,
                 table="e2e_device_keys_json",
@@ -215,6 +232,7 @@ class EndToEndKeyStore(EndToEndKeyWorkerStore, SQLBaseStore):
             new_key_json = encode_canonical_json(device_keys).decode("utf-8")
 
             if old_key_json == new_key_json:
+                log_kv({"Message": "Device key already stored."})
                 return False
 
             self._simple_upsert_txn(
@@ -223,7 +241,7 @@ class EndToEndKeyStore(EndToEndKeyWorkerStore, SQLBaseStore):
                 keyvalues={"user_id": user_id, "device_id": device_id},
                 values={"ts_added_ms": time_now, "key_json": new_key_json},
             )
-
+            log_kv({"message": "Device keys stored."})
             return True
 
         return self.runInteraction("set_e2e_device_keys", _set_e2e_device_keys_txn)
@@ -231,6 +249,7 @@ class EndToEndKeyStore(EndToEndKeyWorkerStore, SQLBaseStore):
     def claim_e2e_one_time_keys(self, query_list):
         """Take a list of one time keys out of the database"""
 
+        @trace
         def _claim_e2e_one_time_keys(txn):
             sql = (
                 "SELECT key_id, key_json FROM e2e_one_time_keys_json"
@@ -252,7 +271,13 @@ class EndToEndKeyStore(EndToEndKeyWorkerStore, SQLBaseStore):
                 " AND key_id = ?"
             )
             for user_id, device_id, algorithm, key_id in delete:
+                log_kv(
+                    {
+                        "message": "Executing claim e2e_one_time_keys transaction on database."
+                    }
+                )
                 txn.execute(sql, (user_id, device_id, algorithm, key_id))
+                log_kv({"message": "finished executing and invalidating cache"})
                 self._invalidate_cache_and_stream(
                     txn, self.count_e2e_one_time_keys, (user_id, device_id)
                 )
@@ -262,6 +287,13 @@ class EndToEndKeyStore(EndToEndKeyWorkerStore, SQLBaseStore):
 
     def delete_e2e_keys_by_device(self, user_id, device_id):
         def delete_e2e_keys_by_device_txn(txn):
+            log_kv(
+                {
+                    "message": "Deleting keys for device",
+                    "device_id": device_id,
+                    "user_id": user_id,
+                }
+            )
             self._simple_delete_txn(
                 txn,
                 table="e2e_device_keys_json",
diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index ac876287fc..ddf7ab6479 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 json
+from canonicaljson import encode_canonical_json, json
 from prometheus_client import Counter, Histogram
 
 from twisted.internet import defer
@@ -33,6 +33,7 @@ from synapse.api.constants import EventTypes
 from synapse.api.errors import SynapseError
 from synapse.events import EventBase  # noqa: F401
 from synapse.events.snapshot import EventContext  # noqa: F401
+from synapse.events.utils import prune_event_dict
 from synapse.logging.context import PreserveLoggingContext, make_deferred_yieldable
 from synapse.logging.utils import log_function
 from synapse.metrics import BucketCollector
@@ -262,6 +263,14 @@ class EventsStore(
 
         hs.get_clock().looping_call(read_forward_extremities, 60 * 60 * 1000)
 
+        def _censor_redactions():
+            return run_as_background_process(
+                "_censor_redactions", self._censor_redactions
+            )
+
+        if self.hs.config.redaction_retention_period is not None:
+            hs.get_clock().looping_call(_censor_redactions, 5 * 60 * 1000)
+
     @defer.inlineCallbacks
     def _read_forward_extremities(self):
         def fetch(txn):
@@ -810,7 +819,7 @@ class EventsStore(
         # If they old and new groups are the same then we don't need to do
         # anything.
         if old_state_groups == new_state_groups:
-            return (None, None)
+            return None, None
 
         if len(new_state_groups) == 1 and len(old_state_groups) == 1:
             # If we're going from one state group to another, lets check if
@@ -827,7 +836,7 @@ class EventsStore(
                 # the current state in memory then lets also return that,
                 # but it doesn't matter if we don't.
                 new_state = state_groups_map.get(new_state_group)
-                return (new_state, delta_ids)
+                return new_state, delta_ids
 
         # Now that we have calculated new_state_groups we need to get
         # their state IDs so we can resolve to a single state set.
@@ -839,7 +848,7 @@ class EventsStore(
         if len(new_state_groups) == 1:
             # If there is only one state group, then we know what the current
             # state is.
-            return (state_groups_map[new_state_groups.pop()], None)
+            return state_groups_map[new_state_groups.pop()], None
 
         # Ok, we need to defer to the state handler to resolve our state sets.
 
@@ -868,7 +877,7 @@ class EventsStore(
             state_res_store=StateResolutionStore(self),
         )
 
-        return (res.state, None)
+        return res.state, None
 
     @defer.inlineCallbacks
     def _calculate_state_delta(self, room_id, current_state):
@@ -891,7 +900,7 @@ class EventsStore(
             if ev_id != existing_state.get(key)
         }
 
-        return (to_delete, to_insert)
+        return to_delete, to_insert
 
     @log_function
     def _persist_events_txn(
@@ -1302,15 +1311,11 @@ class EventsStore(
             "event_reference_hashes",
             "event_search",
             "event_to_state_groups",
-            "guest_access",
-            "history_visibility",
             "local_invites",
-            "room_names",
             "state_events",
             "rejections",
             "redactions",
             "room_memberships",
-            "topics",
         ):
             txn.executemany(
                 "DELETE FROM %s WHERE event_id = ?" % (table,),
@@ -1454,10 +1459,10 @@ class EventsStore(
 
         for event, _ in events_and_contexts:
             if event.type == EventTypes.Name:
-                # Insert into the room_names and event_search tables.
+                # Insert into the event_search table.
                 self._store_room_name_txn(txn, event)
             elif event.type == EventTypes.Topic:
-                # Insert into the topics table and event_search table.
+                # Insert into the event_search table.
                 self._store_room_topic_txn(txn, event)
             elif event.type == EventTypes.Message:
                 # Insert into the event_search table.
@@ -1465,12 +1470,6 @@ class EventsStore(
             elif event.type == EventTypes.Redaction:
                 # Insert into the redactions table.
                 self._store_redaction(txn, event)
-            elif event.type == EventTypes.RoomHistoryVisibility:
-                # Insert into the event_search table.
-                self._store_history_visibility_txn(txn, event)
-            elif event.type == EventTypes.GuestAccess:
-                # Insert into the event_search table.
-                self._store_guest_access_txn(txn, event)
 
             self._handle_event_relations(txn, event)
 
@@ -1559,6 +1558,98 @@ class EventsStore(
         )
 
     @defer.inlineCallbacks
+    def _censor_redactions(self):
+        """Censors all redactions older than the configured period that haven't
+        been censored yet.
+
+        By censor we mean update the event_json table with the redacted event.
+
+        Returns:
+            Deferred
+        """
+
+        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
+        )
+
+        # We fetch all redactions that:
+        #   1. point to an event we have,
+        #   2. has a stream ordering 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
+            )
+            WHERE NOT have_censored
+            AND ? <= redact_event.stream_ordering AND redact_event.stream_ordering <= ?
+            ORDER BY redact_event.stream_ordering ASC
+            LIMIT ?
+        """
+
+        rows = yield self._execute(
+            "_censor_redactions_fetch", None, sql, -max_pos, max_pos, 100
+        )
+
+        updates = []
+
+        for redaction_id, event_id in rows:
+            redaction_event = yield self.get_event(redaction_id, allow_none=True)
+            original_event = yield self.get_event(
+                event_id, allow_rejected=True, allow_none=True
+            )
+
+            # The SQL above ensures that we have both the redaction and
+            # original event, so if the `get_event` calls return None it
+            # means that the redaction wasn't allowed. Either way we know that
+            # the result won't change so we mark the fact that we've checked.
+            if (
+                redaction_event
+                and original_event
+                and original_event.internal_metadata.is_redacted()
+            ):
+                # Redaction was allowed
+                pruned_json = encode_canonical_json(
+                    prune_event_dict(original_event.get_dict())
+                )
+            else:
+                # Redaction wasn't allowed
+                pruned_json = None
+
+            updates.append((redaction_id, event_id, pruned_json))
+
+        def _update_censor_txn(txn):
+            for redaction_id, event_id, pruned_json in updates:
+                if pruned_json:
+                    self._simple_update_one_txn(
+                        txn,
+                        table="event_json",
+                        keyvalues={"event_id": event_id},
+                        updatevalues={"json": pruned_json},
+                    )
+
+                self._simple_update_one_txn(
+                    txn,
+                    table="redactions",
+                    keyvalues={"event_id": redaction_id},
+                    updatevalues={"have_censored": True},
+                )
+
+        yield self.runInteraction("_update_censor_txn", _update_censor_txn)
+
+    @defer.inlineCallbacks
     def count_daily_messages(self):
         """
         Returns an estimate of the number of messages sent in the last day.
@@ -2191,6 +2282,144 @@ class EventsStore(
 
         return to_delete, to_dedelta
 
+    def purge_room(self, room_id):
+        """Deletes all record of a room
+
+        Args:
+            room_id (str):
+        """
+
+        return self.runInteraction("purge_room", self._purge_room_txn, room_id)
+
+    def _purge_room_txn(self, txn, room_id):
+        # first we have to delete the state groups states
+        logger.info("[purge] removing %s from state_groups_state", room_id)
+
+        txn.execute(
+            """
+            DELETE FROM state_groups_state WHERE state_group IN (
+              SELECT state_group FROM events JOIN event_to_state_groups USING(event_id)
+              WHERE events.room_id=?
+            )
+            """,
+            (room_id,),
+        )
+
+        # ... and the state group edges
+        logger.info("[purge] removing %s from state_group_edges", room_id)
+
+        txn.execute(
+            """
+            DELETE FROM state_group_edges WHERE state_group IN (
+              SELECT state_group FROM events JOIN event_to_state_groups USING(event_id)
+              WHERE events.room_id=?
+            )
+            """,
+            (room_id,),
+        )
+
+        # ... and the state groups
+        logger.info("[purge] removing %s from state_groups", room_id)
+
+        txn.execute(
+            """
+            DELETE FROM state_groups WHERE id IN (
+              SELECT state_group FROM events JOIN event_to_state_groups USING(event_id)
+              WHERE events.room_id=?
+            )
+            """,
+            (room_id,),
+        )
+
+        # and then tables which lack an index on room_id but have one on event_id
+        for table in (
+            "event_auth",
+            "event_edges",
+            "event_push_actions_staging",
+            "event_reference_hashes",
+            "event_relations",
+            "event_to_state_groups",
+            "redactions",
+            "rejections",
+            "state_events",
+        ):
+            logger.info("[purge] removing %s from %s", room_id, table)
+
+            txn.execute(
+                """
+                DELETE FROM %s WHERE event_id IN (
+                  SELECT event_id FROM events WHERE room_id=?
+                )
+                """
+                % (table,),
+                (room_id,),
+            )
+
+        # and finally, the tables with an index on room_id (or no useful index)
+        for table in (
+            "current_state_events",
+            "event_backward_extremities",
+            "event_forward_extremities",
+            "event_json",
+            "event_push_actions",
+            "event_search",
+            "events",
+            "group_rooms",
+            "public_room_list_stream",
+            "receipts_graph",
+            "receipts_linearized",
+            "room_aliases",
+            "room_depth",
+            "room_memberships",
+            "room_stats_state",
+            "room_stats_current",
+            "room_stats_historical",
+            "room_stats_earliest_token",
+            "rooms",
+            "stream_ordering_to_exterm",
+            "topics",
+            "users_in_public_rooms",
+            "users_who_share_private_rooms",
+            # no useful index, but let's clear them anyway
+            "appservice_room_list",
+            "e2e_room_keys",
+            "event_push_summary",
+            "pusher_throttle",
+            "group_summary_rooms",
+            "local_invites",
+            "room_account_data",
+            "room_tags",
+        ):
+            logger.info("[purge] removing %s from %s", room_id, table)
+            txn.execute("DELETE FROM %s WHERE room_id=?" % (table,), (room_id,))
+
+        # Other tables we do NOT need to clear out:
+        #
+        #  - blocked_rooms
+        #    This is important, to make sure that we don't accidentally rejoin a blocked
+        #    room after it was purged
+        #
+        #  - user_directory
+        #    This has a room_id column, but it is unused
+        #
+
+        # Other tables that we might want to consider clearing out include:
+        #
+        #  - event_reports
+        #       Given that these are intended for abuse management my initial
+        #       inclination is to leave them in place.
+        #
+        #  - current_state_delta_stream
+        #  - ex_outlier_stream
+        #  - room_tags_revisions
+        #       The problem with these is that they are largeish and there is no room_id
+        #       index on them. In any case we should be clearing out 'stream' tables
+        #       periodically anyway (#5888)
+
+        # TODO: we could probably usefully do a bunch of cache invalidation here
+
+        logger.info("[purge] done")
+
     @defer.inlineCallbacks
     def is_event_after(self, event_id1, event_id2):
         """Returns True if event_id1 is after event_id2 in the stream
diff --git a/synapse/storage/prepare_database.py b/synapse/storage/prepare_database.py
index d20eacda59..e96eed8a6d 100644
--- a/synapse/storage/prepare_database.py
+++ b/synapse/storage/prepare_database.py
@@ -238,6 +238,13 @@ def _upgrade_existing_database(
 
     logger.debug("applied_delta_files: %s", applied_delta_files)
 
+    if isinstance(database_engine, PostgresEngine):
+        specific_engine_extension = ".postgres"
+    else:
+        specific_engine_extension = ".sqlite"
+
+    specific_engine_extensions = (".sqlite", ".postgres")
+
     for v in range(start_ver, SCHEMA_VERSION + 1):
         logger.info("Upgrading schema to v%d", v)
 
@@ -274,15 +281,22 @@ def _upgrade_existing_database(
                 # Sometimes .pyc files turn up anyway even though we've
                 # disabled their generation; e.g. from distribution package
                 # installers. Silently skip it
-                pass
+                continue
             elif ext == ".sql":
                 # A plain old .sql file, just read and execute it
                 logger.info("Applying schema %s", relative_path)
                 executescript(cur, absolute_path)
+            elif ext == specific_engine_extension and root_name.endswith(".sql"):
+                # A .sql file specific to our engine; just read and execute it
+                logger.info("Applying engine-specific schema %s", relative_path)
+                executescript(cur, absolute_path)
+            elif ext in specific_engine_extensions and root_name.endswith(".sql"):
+                # A .sql file for a different engine; skip it.
+                continue
             else:
                 # Not a valid delta file.
-                logger.warn(
-                    "Found directory entry that did not end in .py or" " .sql: %s",
+                logger.warning(
+                    "Found directory entry that did not end in .py or .sql: %s",
                     relative_path,
                 )
                 continue
@@ -290,7 +304,7 @@ def _upgrade_existing_database(
             # Mark as done.
             cur.execute(
                 database_engine.convert_param_style(
-                    "INSERT INTO applied_schema_deltas (version, file)" " VALUES (?,?)"
+                    "INSERT INTO applied_schema_deltas (version, file) VALUES (?,?)"
                 ),
                 (v, relative_path),
             )
@@ -298,7 +312,7 @@ def _upgrade_existing_database(
             cur.execute("DELETE FROM schema_version")
             cur.execute(
                 database_engine.convert_param_style(
-                    "INSERT INTO schema_version (version, upgraded)" " VALUES (?,?)"
+                    "INSERT INTO schema_version (version, upgraded) VALUES (?,?)"
                 ),
                 (v, True),
             )
diff --git a/synapse/storage/presence.py b/synapse/storage/presence.py
index 1a0f2d5768..5db6f2d84a 100644
--- a/synapse/storage/presence.py
+++ b/synapse/storage/presence.py
@@ -90,7 +90,7 @@ class PresenceStore(SQLBaseStore):
                 presence_states,
             )
 
-        return (stream_orderings[-1], self._presence_id_gen.get_current_token())
+        return stream_orderings[-1], self._presence_id_gen.get_current_token()
 
     def _update_presence_txn(self, txn, stream_orderings, presence_states):
         for stream_id, state in zip(stream_orderings, presence_states):
diff --git a/synapse/storage/profile.py b/synapse/storage/profile.py
index 8a5d8e9b18..912c1df6be 100644
--- a/synapse/storage/profile.py
+++ b/synapse/storage/profile.py
@@ -35,7 +35,6 @@ class ProfileWorkerStore(SQLBaseStore):
             if e.code == 404:
                 # no match
                 return ProfileInfo(None, None)
-                return
             else:
                 raise
 
diff --git a/synapse/storage/pusher.py b/synapse/storage/pusher.py
index b431d24b8a..3e0e834a62 100644
--- a/synapse/storage/pusher.py
+++ b/synapse/storage/pusher.py
@@ -133,7 +133,7 @@ class PusherWorkerStore(SQLBaseStore):
             txn.execute(sql, (last_id, current_id, limit))
             deleted = txn.fetchall()
 
-            return (updated, deleted)
+            return updated, deleted
 
         return self.runInteraction(
             "get_all_updated_pushers", get_all_updated_pushers_txn
diff --git a/synapse/storage/receipts.py b/synapse/storage/receipts.py
index 6aa6d98ebb..290ddb30e8 100644
--- a/synapse/storage/receipts.py
+++ b/synapse/storage/receipts.py
@@ -478,7 +478,7 @@ class ReceiptsStore(ReceiptsWorkerStore):
 
         max_persisted_id = self._receipts_id_gen.get_current_token()
 
-        return (stream_id, max_persisted_id)
+        return stream_id, max_persisted_id
 
     def insert_graph_receipt(self, room_id, receipt_type, user_id, event_ids, data):
         return self.runInteraction(
diff --git a/synapse/storage/registration.py b/synapse/storage/registration.py
index 55e4e84d71..109052fa41 100644
--- a/synapse/storage/registration.py
+++ b/synapse/storage/registration.py
@@ -56,6 +56,7 @@ class RegistrationWorkerStore(SQLBaseStore):
                 "consent_server_notice_sent",
                 "appservice_id",
                 "creation_ts",
+                "user_type",
             ],
             allow_none=True,
             desc="get_user_by_id",
@@ -272,6 +273,14 @@ class RegistrationWorkerStore(SQLBaseStore):
 
     @defer.inlineCallbacks
     def is_server_admin(self, user):
+        """Determines if a user is an admin of this homeserver.
+
+        Args:
+            user (UserID): user ID of the user to test
+
+        Returns (bool):
+            true iff the user is a server admin, false otherwise.
+        """
         res = yield self._simple_select_one_onecol(
             table="users",
             keyvalues={"name": user.to_string()},
@@ -282,6 +291,21 @@ class RegistrationWorkerStore(SQLBaseStore):
 
         return res if res else False
 
+    def set_server_admin(self, user, admin):
+        """Sets whether a user is an admin of this homeserver.
+
+        Args:
+            user (UserID): user ID of the user to test
+            admin (bool): true iff the user is to be a server admin,
+                false otherwise.
+        """
+        return self._simple_update_one(
+            table="users",
+            keyvalues={"name": user.to_string()},
+            updatevalues={"admin": 1 if admin else 0},
+            desc="set_server_admin",
+        )
+
     def _query_for_auth(self, txn, token):
         sql = (
             "SELECT users.name, users.is_guest, access_tokens.id as token_id,"
@@ -299,6 +323,19 @@ class RegistrationWorkerStore(SQLBaseStore):
         return None
 
     @cachedInlineCallbacks()
+    def is_real_user(self, user_id):
+        """Determines if the user is a real user, ie does not have a 'user_type'.
+
+        Args:
+            user_id (str): user id to test
+
+        Returns:
+            Deferred[bool]: True if user 'user_type' is null or empty string
+        """
+        res = yield self.runInteraction("is_real_user", self.is_real_user_txn, user_id)
+        return res
+
+    @cachedInlineCallbacks()
     def is_support_user(self, user_id):
         """Determines if the user is of type UserTypes.SUPPORT
 
@@ -313,6 +350,16 @@ class RegistrationWorkerStore(SQLBaseStore):
         )
         return res
 
+    def is_real_user_txn(self, txn, user_id):
+        res = self._simple_select_one_onecol_txn(
+            txn=txn,
+            table="users",
+            keyvalues={"name": user_id},
+            retcol="user_type",
+            allow_none=True,
+        )
+        return res is None
+
     def is_support_user_txn(self, txn, user_id):
         res = self._simple_select_one_onecol_txn(
             txn=txn,
@@ -398,6 +445,20 @@ class RegistrationWorkerStore(SQLBaseStore):
         return ret
 
     @defer.inlineCallbacks
+    def count_real_users(self):
+        """Counts all users without a special user_type registered on the homeserver."""
+
+        def _count_users(txn):
+            txn.execute("SELECT COUNT(*) AS users FROM users where user_type is null")
+            rows = self.cursor_to_dict(txn)
+            if rows:
+                return rows[0]["users"]
+            return 0
+
+        ret = yield self.runInteraction("count_real_users", _count_users)
+        return ret
+
+    @defer.inlineCallbacks
     def find_next_generated_user_id_localpart(self):
         """
         Gets the localpart of the next generated user ID.
@@ -590,6 +651,85 @@ class RegistrationWorkerStore(SQLBaseStore):
         # Convert the integer into a boolean.
         return res == 1
 
+    def get_threepid_validation_session(
+        self, medium, client_secret, address=None, sid=None, validated=True
+    ):
+        """Gets a session_id and last_send_attempt (if available) for a
+        client_secret/medium/(address|session_id) combo
+
+        Args:
+            medium (str|None): The medium of the 3PID
+            address (str|None): The address of the 3PID
+            sid (str|None): The ID of the validation session
+            client_secret (str|None): A unique string provided by the client to
+                help identify this validation attempt
+            validated (bool|None): Whether sessions should be filtered by
+                whether they have been validated already or not. None to
+                perform no filtering
+
+        Returns:
+            deferred {str, int}|None: A dict containing the
+                latest session_id and send_attempt count for this 3PID.
+                Otherwise None if there hasn't been a previous attempt
+        """
+        keyvalues = {"medium": medium, "client_secret": client_secret}
+        if address:
+            keyvalues["address"] = address
+        if sid:
+            keyvalues["session_id"] = sid
+
+        assert address or sid
+
+        def get_threepid_validation_session_txn(txn):
+            sql = """
+                SELECT address, session_id, medium, client_secret,
+                last_send_attempt, validated_at
+                FROM threepid_validation_session WHERE %s
+                """ % (
+                " AND ".join("%s = ?" % k for k in iterkeys(keyvalues)),
+            )
+
+            if validated is not None:
+                sql += " AND validated_at IS " + ("NOT NULL" if validated else "NULL")
+
+            sql += " LIMIT 1"
+
+            txn.execute(sql, list(keyvalues.values()))
+            rows = self.cursor_to_dict(txn)
+            if not rows:
+                return None
+
+            return rows[0]
+
+        return self.runInteraction(
+            "get_threepid_validation_session", get_threepid_validation_session_txn
+        )
+
+    def delete_threepid_session(self, session_id):
+        """Removes a threepid validation session from the database. This can
+        be done after validation has been performed and whatever action was
+        waiting on it has been carried out
+
+        Args:
+            session_id (str): The ID of the session to delete
+        """
+
+        def delete_threepid_session_txn(txn):
+            self._simple_delete_txn(
+                txn,
+                table="threepid_validation_token",
+                keyvalues={"session_id": session_id},
+            )
+            self._simple_delete_txn(
+                txn,
+                table="threepid_validation_session",
+                keyvalues={"session_id": session_id},
+            )
+
+        return self.runInteraction(
+            "delete_threepid_session", delete_threepid_session_txn
+        )
+
 
 class RegistrationStore(
     RegistrationWorkerStore, background_updates.BackgroundUpdateStore
@@ -845,6 +985,17 @@ class RegistrationStore(
                 (user_id_obj.localpart, create_profile_with_displayname),
             )
 
+        if self.hs.config.stats_enabled:
+            # we create a new completed user statistics row
+
+            # we don't strictly need current_token since this user really can't
+            # have any state deltas before now (as it is a new user), but still,
+            # we include it for completeness.
+            current_token = self._get_max_stream_id_in_current_state_deltas_txn(txn)
+            self._update_stats_delta_txn(
+                txn, now, "user", user_id, {}, complete_with_stream_id=current_token
+            )
+
         self._invalidate_cache_and_stream(txn, self.get_user_by_id, (user_id,))
         txn.call_after(self.is_guest.invalidate, (user_id,))
 
@@ -1047,60 +1198,6 @@ class RegistrationStore(
 
         return 1
 
-    def get_threepid_validation_session(
-        self, medium, client_secret, address=None, sid=None, validated=True
-    ):
-        """Gets a session_id and last_send_attempt (if available) for a
-        client_secret/medium/(address|session_id) combo
-
-        Args:
-            medium (str|None): The medium of the 3PID
-            address (str|None): The address of the 3PID
-            sid (str|None): The ID of the validation session
-            client_secret (str|None): A unique string provided by the client to
-                help identify this validation attempt
-            validated (bool|None): Whether sessions should be filtered by
-                whether they have been validated already or not. None to
-                perform no filtering
-
-        Returns:
-            deferred {str, int}|None: A dict containing the
-                latest session_id and send_attempt count for this 3PID.
-                Otherwise None if there hasn't been a previous attempt
-        """
-        keyvalues = {"medium": medium, "client_secret": client_secret}
-        if address:
-            keyvalues["address"] = address
-        if sid:
-            keyvalues["session_id"] = sid
-
-        assert address or sid
-
-        def get_threepid_validation_session_txn(txn):
-            sql = """
-                SELECT address, session_id, medium, client_secret,
-                last_send_attempt, validated_at
-                FROM threepid_validation_session WHERE %s
-                """ % (
-                " AND ".join("%s = ?" % k for k in iterkeys(keyvalues)),
-            )
-
-            if validated is not None:
-                sql += " AND validated_at IS " + ("NOT NULL" if validated else "NULL")
-
-            sql += " LIMIT 1"
-
-            txn.execute(sql, list(keyvalues.values()))
-            rows = self.cursor_to_dict(txn)
-            if not rows:
-                return None
-
-            return rows[0]
-
-        return self.runInteraction(
-            "get_threepid_validation_session", get_threepid_validation_session_txn
-        )
-
     def validate_threepid_session(self, session_id, client_secret, token, current_ts):
         """Attempt to validate a threepid session using a token
 
@@ -1116,6 +1213,7 @@ class RegistrationStore(
             deferred str|None: A str representing a link to redirect the user
             to if there is one.
         """
+
         # Insert everything into a transaction in order to run atomically
         def validate_threepid_session_txn(txn):
             row = self._simple_select_one_txn(
@@ -1287,31 +1385,6 @@ class RegistrationStore(
             self.clock.time_msec(),
         )
 
-    def delete_threepid_session(self, session_id):
-        """Removes a threepid validation session from the database. This can
-        be done after validation has been performed and whatever action was
-        waiting on it has been carried out
-
-        Args:
-            session_id (str): The ID of the session to delete
-        """
-
-        def delete_threepid_session_txn(txn):
-            self._simple_delete_txn(
-                txn,
-                table="threepid_validation_token",
-                keyvalues={"session_id": session_id},
-            )
-            self._simple_delete_txn(
-                txn,
-                table="threepid_validation_session",
-                keyvalues={"session_id": session_id},
-            )
-
-        return self.runInteraction(
-            "delete_threepid_session", delete_threepid_session_txn
-        )
-
     def set_user_deactivated_status_txn(self, txn, user_id, deactivated):
         self._simple_update_one_txn(
             txn=txn,
diff --git a/synapse/storage/room.py b/synapse/storage/room.py
index bc606292b8..08e13f3a3b 100644
--- a/synapse/storage/room.py
+++ b/synapse/storage/room.py
@@ -386,32 +386,12 @@ class RoomStore(RoomWorkerStore, SearchStore):
 
     def _store_room_topic_txn(self, txn, event):
         if hasattr(event, "content") and "topic" in event.content:
-            self._simple_insert_txn(
-                txn,
-                "topics",
-                {
-                    "event_id": event.event_id,
-                    "room_id": event.room_id,
-                    "topic": event.content["topic"],
-                },
-            )
-
             self.store_event_search_txn(
                 txn, event, "content.topic", event.content["topic"]
             )
 
     def _store_room_name_txn(self, txn, event):
         if hasattr(event, "content") and "name" in event.content:
-            self._simple_insert_txn(
-                txn,
-                "room_names",
-                {
-                    "event_id": event.event_id,
-                    "room_id": event.room_id,
-                    "name": event.content["name"],
-                },
-            )
-
             self.store_event_search_txn(
                 txn, event, "content.name", event.content["name"]
             )
@@ -422,21 +402,6 @@ class RoomStore(RoomWorkerStore, SearchStore):
                 txn, event, "content.body", event.content["body"]
             )
 
-    def _store_history_visibility_txn(self, txn, event):
-        self._store_content_index_txn(txn, event, "history_visibility")
-
-    def _store_guest_access_txn(self, txn, event):
-        self._store_content_index_txn(txn, event, "guest_access")
-
-    def _store_content_index_txn(self, txn, event, key):
-        if hasattr(event, "content") and key in event.content:
-            sql = (
-                "INSERT INTO %(key)s"
-                " (event_id, room_id, %(key)s)"
-                " VALUES (?, ?, ?)" % {"key": key}
-            )
-            txn.execute(sql, (event.event_id, event.room_id, event.content[key]))
-
     def add_event_report(
         self, room_id, event_id, user_id, reason, content, received_ts
     ):
diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index eecb276465..4df8ebdacd 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -24,8 +24,10 @@ from canonicaljson import json
 from twisted.internet import defer
 
 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.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
@@ -74,6 +76,63 @@ class RoomMemberWorkerStore(EventsWorkerStore):
         self._check_safe_current_state_events_membership_updated_txn(txn)
         txn.close()
 
+        if self.hs.config.metrics_flags.known_servers:
+            self._known_servers_count = 1
+            self.hs.get_clock().looping_call(
+                run_as_background_process,
+                60 * 1000,
+                "_count_known_servers",
+                self._count_known_servers,
+            )
+            self.hs.get_clock().call_later(
+                1000,
+                run_as_background_process,
+                "_count_known_servers",
+                self._count_known_servers,
+            )
+            LaterGauge(
+                "synapse_federation_known_servers",
+                "",
+                [],
+                lambda: self._known_servers_count,
+            )
+
+    @defer.inlineCallbacks
+    def _count_known_servers(self):
+        """
+        Count the servers that this server knows about.
+
+        The statistic is stored on the class for the
+        `synapse_federation_known_servers` LaterGauge to collect.
+        """
+
+        def _transact(txn):
+            if isinstance(self.database_engine, Sqlite3Engine):
+                query = """
+                    SELECT COUNT(DISTINCT substr(out.user_id, pos+1))
+                    FROM (
+                        SELECT rm.user_id as user_id, instr(rm.user_id, ':')
+                            AS pos FROM room_memberships as rm
+                        INNER JOIN current_state_events as c ON rm.event_id = c.event_id
+                        WHERE c.type = 'm.room.member'
+                    ) as out
+                """
+            else:
+                query = """
+                    SELECT COUNT(DISTINCT split_part(state_key, ':', 2))
+                    FROM current_state_events
+                    WHERE type = 'm.room.member' AND membership = 'join';
+                """
+            txn.execute(query)
+            return list(txn)[0][0]
+
+        count = yield self.runInteraction("get_known_servers", _transact)
+
+        # We always know about ourselves, even if we have nothing in
+        # room_memberships (for example, the server is new).
+        self._known_servers_count = max([count, 1])
+        return self._known_servers_count
+
     def _check_safe_current_state_events_membership_updated_txn(self, txn):
         """Checks if it is safe to assume the new current_state_events
         membership column is up to date
@@ -112,29 +171,31 @@ class RoomMemberWorkerStore(EventsWorkerStore):
 
     @cached(max_entries=100000, iterable=True)
     def get_users_in_room(self, room_id):
-        def f(txn):
-            # If we can assume current_state_events.membership is up to date
-            # then we can avoid a join, which is a Very Good Thing given how
-            # frequently this function gets called.
-            if self._current_state_events_membership_up_to_date:
-                sql = """
-                    SELECT state_key FROM current_state_events
-                    WHERE type = 'm.room.member' AND room_id = ? AND membership = ?
-                """
-            else:
-                sql = """
-                    SELECT state_key FROM room_memberships as m
-                    INNER JOIN current_state_events as c
-                    ON m.event_id = c.event_id
-                    AND m.room_id = c.room_id
-                    AND m.user_id = c.state_key
-                    WHERE c.type = 'm.room.member' AND c.room_id = ? AND m.membership = ?
-                """
+        return self.runInteraction(
+            "get_users_in_room", self.get_users_in_room_txn, room_id
+        )
 
-            txn.execute(sql, (room_id, Membership.JOIN))
-            return [to_ascii(r[0]) for r in txn]
+    def get_users_in_room_txn(self, txn, room_id):
+        # If we can assume current_state_events.membership is up to date
+        # then we can avoid a join, which is a Very Good Thing given how
+        # frequently this function gets called.
+        if self._current_state_events_membership_up_to_date:
+            sql = """
+                SELECT state_key FROM current_state_events
+                WHERE type = 'm.room.member' AND room_id = ? AND membership = ?
+            """
+        else:
+            sql = """
+                SELECT state_key FROM room_memberships as m
+                INNER JOIN current_state_events as c
+                ON m.event_id = c.event_id
+                AND m.room_id = c.room_id
+                AND m.user_id = c.state_key
+                WHERE c.type = 'm.room.member' AND c.room_id = ? AND m.membership = ?
+            """
 
-        return self.runInteraction("get_users_in_room", f)
+        txn.execute(sql, (room_id, Membership.JOIN))
+        return [to_ascii(r[0]) for r in txn]
 
     @cached(max_entries=100000)
     def get_room_summary(self, room_id):
diff --git a/synapse/storage/schema/delta/56/add_spans_to_device_lists.sql b/synapse/storage/schema/delta/56/add_spans_to_device_lists.sql
new file mode 100644
index 0000000000..41807eb1e7
--- /dev/null
+++ b/synapse/storage/schema/delta/56/add_spans_to_device_lists.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.
+ */
+
+/*
+ * Opentracing context data for inclusion in the device_list_update EDUs, as a
+ * json-encoded dictionary. NULL if opentracing is disabled (or not enabled for this destination).
+ */
+ALTER TABLE device_lists_outbound_pokes ADD opentracing_context TEXT;
diff --git a/synapse/storage/schema/delta/56/destinations_failure_ts.sql b/synapse/storage/schema/delta/56/destinations_failure_ts.sql
new file mode 100644
index 0000000000..f00889290b
--- /dev/null
+++ b/synapse/storage/schema/delta/56/destinations_failure_ts.sql
@@ -0,0 +1,25 @@
+/* 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.
+ */
+
+/*
+ * Record the timestamp when a given server started failing
+ */
+ALTER TABLE destinations ADD failure_ts BIGINT;
+
+/* as a rough approximation, we assume that the server started failing at
+ * retry_interval before the last retry
+ */
+UPDATE destinations SET failure_ts = retry_last_ts - retry_interval
+    WHERE retry_last_ts > 0;
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/fix_room_keys_index.sql b/synapse/storage/schema/delta/56/fix_room_keys_index.sql
new file mode 100644
index 0000000000..014cb3b538
--- /dev/null
+++ b/synapse/storage/schema/delta/56/fix_room_keys_index.sql
@@ -0,0 +1,18 @@
+/* Copyright 2019 Matrix.org Foundation CIC
+ *
+ * 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.
+ */
+
+-- version is supposed to be part of the room keys index
+CREATE UNIQUE INDEX e2e_room_keys_with_version_idx ON e2e_room_keys(user_id, version, room_id, session_id);
+DROP INDEX IF EXISTS e2e_room_keys_idx;
diff --git a/synapse/storage/schema/delta/56/redaction_censor.sql b/synapse/storage/schema/delta/56/redaction_censor.sql
new file mode 100644
index 0000000000..fe51b02309
--- /dev/null
+++ b/synapse/storage/schema/delta/56/redaction_censor.sql
@@ -0,0 +1,17 @@
+/* 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 have_censored BOOL NOT NULL DEFAULT false;
+CREATE INDEX redactions_have_censored ON redactions(event_id) WHERE not have_censored;
diff --git a/synapse/storage/schema/delta/56/stats_separated.sql b/synapse/storage/schema/delta/56/stats_separated.sql
new file mode 100644
index 0000000000..163529c071
--- /dev/null
+++ b/synapse/storage/schema/delta/56/stats_separated.sql
@@ -0,0 +1,152 @@
+/* Copyright 2018 New Vector 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.
+ * 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.
+ */
+
+
+----- First clean up from previous versions of room stats.
+
+-- First remove old stats stuff
+DROP TABLE IF EXISTS room_stats;
+DROP TABLE IF EXISTS room_state;
+DROP TABLE IF EXISTS room_stats_state;
+DROP TABLE IF EXISTS user_stats;
+DROP TABLE IF EXISTS room_stats_earliest_tokens;
+DROP TABLE IF EXISTS _temp_populate_stats_position;
+DROP TABLE IF EXISTS _temp_populate_stats_rooms;
+DROP TABLE IF EXISTS stats_stream_pos;
+
+-- Unschedule old background updates if they're still scheduled
+DELETE FROM background_updates WHERE update_name IN (
+    'populate_stats_createtables',
+    'populate_stats_process_rooms',
+    'populate_stats_process_users',
+    'populate_stats_cleanup'
+);
+
+INSERT INTO background_updates (update_name, progress_json, depends_on) VALUES
+    ('populate_stats_process_rooms', '{}', '');
+
+INSERT INTO background_updates (update_name, progress_json, depends_on) VALUES
+    ('populate_stats_process_users', '{}', 'populate_stats_process_rooms');
+
+----- Create tables for our version of room stats.
+
+-- single-row table to track position of incremental updates
+DROP TABLE IF EXISTS stats_incremental_position;
+CREATE TABLE stats_incremental_position (
+    Lock CHAR(1) NOT NULL DEFAULT 'X' UNIQUE,  -- Makes sure this table only has one row.
+    stream_id  BIGINT NOT NULL,
+    CHECK (Lock='X')
+);
+
+-- insert a null row and make sure it is the only one.
+INSERT INTO stats_incremental_position (
+    stream_id
+) SELECT COALESCE(MAX(stream_ordering), 0) from events;
+
+-- represents PRESENT room statistics for a room
+-- only holds absolute fields
+DROP TABLE IF EXISTS room_stats_current;
+CREATE TABLE room_stats_current (
+    room_id TEXT NOT NULL PRIMARY KEY,
+
+    -- These are absolute counts
+    current_state_events INT NOT NULL,
+    joined_members INT NOT NULL,
+    invited_members INT NOT NULL,
+    left_members INT NOT NULL,
+    banned_members INT NOT NULL,
+
+    local_users_in_room INT NOT NULL,
+
+    -- The maximum delta stream position that this row takes into account.
+    completed_delta_stream_id BIGINT NOT NULL
+);
+
+
+-- represents HISTORICAL room statistics for a room
+DROP TABLE IF EXISTS room_stats_historical;
+CREATE TABLE room_stats_historical (
+    room_id TEXT NOT NULL,
+    -- These stats cover the time from (end_ts - bucket_size)...end_ts (in ms).
+    -- Note that end_ts is quantised.
+    end_ts BIGINT NOT NULL,
+    bucket_size BIGINT NOT NULL,
+
+    -- These stats are absolute counts
+    current_state_events BIGINT NOT NULL,
+    joined_members BIGINT NOT NULL,
+    invited_members BIGINT NOT NULL,
+    left_members BIGINT NOT NULL,
+    banned_members BIGINT NOT NULL,
+    local_users_in_room BIGINT NOT NULL,
+
+    -- These stats are per time slice
+    total_events BIGINT NOT NULL,
+    total_event_bytes BIGINT NOT NULL,
+
+    PRIMARY KEY (room_id, end_ts)
+);
+
+-- We use this index to speed up deletion of ancient room stats.
+CREATE INDEX room_stats_historical_end_ts ON room_stats_historical (end_ts);
+
+-- represents PRESENT statistics for a user
+-- only holds absolute fields
+DROP TABLE IF EXISTS user_stats_current;
+CREATE TABLE user_stats_current (
+    user_id TEXT NOT NULL PRIMARY KEY,
+
+    joined_rooms BIGINT NOT NULL,
+
+    -- The maximum delta stream position that this row takes into account.
+    completed_delta_stream_id BIGINT NOT NULL
+);
+
+-- represents HISTORICAL statistics for a user
+DROP TABLE IF EXISTS user_stats_historical;
+CREATE TABLE user_stats_historical (
+    user_id TEXT NOT NULL,
+    end_ts BIGINT NOT NULL,
+    bucket_size BIGINT NOT NULL,
+
+    joined_rooms BIGINT NOT NULL,
+
+    invites_sent BIGINT NOT NULL,
+    rooms_created BIGINT NOT NULL,
+    total_events BIGINT NOT NULL,
+    total_event_bytes BIGINT NOT NULL,
+
+    PRIMARY KEY (user_id, end_ts)
+);
+
+-- We use this index to speed up deletion of ancient user stats.
+CREATE INDEX user_stats_historical_end_ts ON user_stats_historical (end_ts);
+
+
+CREATE TABLE room_stats_state (
+    room_id TEXT NOT NULL,
+    name TEXT,
+    canonical_alias TEXT,
+    join_rules TEXT,
+    history_visibility TEXT,
+    encryption TEXT,
+    avatar TEXT,
+    guest_access TEXT,
+    is_federatable BOOLEAN,
+    topic TEXT
+);
+
+CREATE UNIQUE INDEX room_stats_state_room ON room_stats_state(room_id);
diff --git a/synapse/storage/schema/delta/56/users_in_public_rooms_idx.sql b/synapse/storage/schema/delta/56/users_in_public_rooms_idx.sql
new file mode 100644
index 0000000000..149f8be8b6
--- /dev/null
+++ b/synapse/storage/schema/delta/56/users_in_public_rooms_idx.sql
@@ -0,0 +1,17 @@
+/* Copyright 2019 Matrix.org Foundation CIC
+ *
+ * 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.
+ */
+
+-- this was apparently forgotten when the table was created back in delta 53.
+CREATE INDEX users_in_public_rooms_r_idx ON users_in_public_rooms(room_id);
diff --git a/synapse/storage/stats.py b/synapse/storage/stats.py
index e13efed417..09190d684e 100644
--- a/synapse/storage/stats.py
+++ b/synapse/storage/stats.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 # Copyright 2018, 2019 New Vector 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.
@@ -14,17 +15,22 @@
 # limitations under the License.
 
 import logging
+from itertools import chain
 
 from twisted.internet import defer
+from twisted.internet.defer import DeferredLock
 
 from synapse.api.constants import EventTypes, Membership
-from synapse.storage.prepare_database import get_statements
+from synapse.storage import PostgresEngine
 from synapse.storage.state_deltas import StateDeltasStore
 from synapse.util.caches.descriptors import cached
 
 logger = logging.getLogger(__name__)
 
 # these fields track absolutes (e.g. total number of rooms on the server)
+# You can think of these as Prometheus Gauges.
+# You can draw these stats on a line graph.
+# Example: number of users in a room
 ABSOLUTE_STATS_FIELDS = {
     "room": (
         "current_state_events",
@@ -32,14 +38,23 @@ ABSOLUTE_STATS_FIELDS = {
         "invited_members",
         "left_members",
         "banned_members",
-        "state_events",
+        "local_users_in_room",
     ),
-    "user": ("public_rooms", "private_rooms"),
+    "user": ("joined_rooms",),
 }
 
-TYPE_TO_ROOM = {"room": ("room_stats", "room_id"), "user": ("user_stats", "user_id")}
+# these fields are per-timeslice and so should be reset to 0 upon a new slice
+# You can draw these stats on a histogram.
+# Example: number of events sent locally during a time slice
+PER_SLICE_FIELDS = {
+    "room": ("total_events", "total_event_bytes"),
+    "user": ("invites_sent", "rooms_created", "total_events", "total_event_bytes"),
+}
+
+TYPE_TO_TABLE = {"room": ("room_stats", "room_id"), "user": ("user_stats", "user_id")}
 
-TEMP_TABLE = "_temp_populate_stats"
+# these are the tables (& ID columns) which contain our actual subjects
+TYPE_TO_ORIGIN_TABLE = {"room": ("rooms", "room_id"), "user": ("users", "name")}
 
 
 class StatsStore(StateDeltasStore):
@@ -51,136 +66,102 @@ class StatsStore(StateDeltasStore):
         self.stats_enabled = hs.config.stats_enabled
         self.stats_bucket_size = hs.config.stats_bucket_size
 
-        self.register_background_update_handler(
-            "populate_stats_createtables", self._populate_stats_createtables
-        )
+        self.stats_delta_processing_lock = DeferredLock()
+
         self.register_background_update_handler(
             "populate_stats_process_rooms", self._populate_stats_process_rooms
         )
         self.register_background_update_handler(
-            "populate_stats_cleanup", self._populate_stats_cleanup
+            "populate_stats_process_users", self._populate_stats_process_users
         )
+        # we no longer need to perform clean-up, but we will give ourselves
+        # the potential to reintroduce it in the future – so documentation
+        # will still encourage the use of this no-op handler.
+        self.register_noop_background_update("populate_stats_cleanup")
+        self.register_noop_background_update("populate_stats_prepare")
 
-    @defer.inlineCallbacks
-    def _populate_stats_createtables(self, progress, batch_size):
-
-        if not self.stats_enabled:
-            yield self._end_background_update("populate_stats_createtables")
-            return 1
-
-        # Get all the rooms that we want to process.
-        def _make_staging_area(txn):
-            # Create the temporary tables
-            stmts = get_statements(
-                """
-                -- We just recreate the table, we'll be reinserting the
-                -- correct entries again later anyway.
-                DROP TABLE IF EXISTS {temp}_rooms;
-
-                CREATE TABLE IF NOT EXISTS {temp}_rooms(
-                    room_id TEXT NOT NULL,
-                    events BIGINT NOT NULL
-                );
-
-                CREATE INDEX {temp}_rooms_events
-                    ON {temp}_rooms(events);
-                CREATE INDEX {temp}_rooms_id
-                    ON {temp}_rooms(room_id);
-            """.format(
-                    temp=TEMP_TABLE
-                ).splitlines()
-            )
-
-            for statement in stmts:
-                txn.execute(statement)
-
-            sql = (
-                "CREATE TABLE IF NOT EXISTS "
-                + TEMP_TABLE
-                + "_position(position TEXT NOT NULL)"
-            )
-            txn.execute(sql)
-
-            # Get rooms we want to process from the database, only adding
-            # those that we haven't (i.e. those not in room_stats_earliest_token)
-            sql = """
-                INSERT INTO %s_rooms (room_id, events)
-                SELECT c.room_id, count(*) FROM current_state_events AS c
-                LEFT JOIN room_stats_earliest_token AS t USING (room_id)
-                WHERE t.room_id IS NULL
-                GROUP BY c.room_id
-            """ % (
-                TEMP_TABLE,
-            )
-            txn.execute(sql)
+    def quantise_stats_time(self, ts):
+        """
+        Quantises a timestamp to be a multiple of the bucket size.
 
-        new_pos = yield self.get_max_stream_id_in_current_state_deltas()
-        yield self.runInteraction("populate_stats_temp_build", _make_staging_area)
-        yield self._simple_insert(TEMP_TABLE + "_position", {"position": new_pos})
-        self.get_earliest_token_for_room_stats.invalidate_all()
+        Args:
+            ts (int): the timestamp to quantise, in milliseconds since the Unix
+                Epoch
 
-        yield self._end_background_update("populate_stats_createtables")
-        return 1
+        Returns:
+            int: a timestamp which
+              - is divisible by the bucket size;
+              - is no later than `ts`; and
+              - is the largest such timestamp.
+        """
+        return (ts // self.stats_bucket_size) * self.stats_bucket_size
 
     @defer.inlineCallbacks
-    def _populate_stats_cleanup(self, progress, batch_size):
+    def _populate_stats_process_users(self, progress, batch_size):
         """
-        Update the user directory stream position, then clean up the old tables.
+        This is a background update which regenerates statistics for users.
         """
         if not self.stats_enabled:
-            yield self._end_background_update("populate_stats_cleanup")
+            yield self._end_background_update("populate_stats_process_users")
             return 1
 
-        position = yield self._simple_select_one_onecol(
-            TEMP_TABLE + "_position", None, "position"
+        last_user_id = progress.get("last_user_id", "")
+
+        def _get_next_batch(txn):
+            sql = """
+                    SELECT DISTINCT name FROM users
+                    WHERE name > ?
+                    ORDER BY name ASC
+                    LIMIT ?
+                """
+            txn.execute(sql, (last_user_id, batch_size))
+            return [r for r, in txn]
+
+        users_to_work_on = yield self.runInteraction(
+            "_populate_stats_process_users", _get_next_batch
         )
-        yield self.update_stats_stream_pos(position)
 
-        def _delete_staging_area(txn):
-            txn.execute("DROP TABLE IF EXISTS " + TEMP_TABLE + "_rooms")
-            txn.execute("DROP TABLE IF EXISTS " + TEMP_TABLE + "_position")
+        # No more rooms -- complete the transaction.
+        if not users_to_work_on:
+            yield self._end_background_update("populate_stats_process_users")
+            return 1
 
-        yield self.runInteraction("populate_stats_cleanup", _delete_staging_area)
+        for user_id in users_to_work_on:
+            yield self._calculate_and_set_initial_state_for_user(user_id)
+            progress["last_user_id"] = user_id
 
-        yield self._end_background_update("populate_stats_cleanup")
-        return 1
+        yield self.runInteraction(
+            "populate_stats_process_users",
+            self._background_update_progress_txn,
+            "populate_stats_process_users",
+            progress,
+        )
+
+        return len(users_to_work_on)
 
     @defer.inlineCallbacks
     def _populate_stats_process_rooms(self, progress, batch_size):
-
+        """
+        This is a background update which regenerates statistics for rooms.
+        """
         if not self.stats_enabled:
             yield self._end_background_update("populate_stats_process_rooms")
             return 1
 
-        # If we don't have progress filed, delete everything.
-        if not progress:
-            yield self.delete_all_stats()
+        last_room_id = progress.get("last_room_id", "")
 
         def _get_next_batch(txn):
-            # Only fetch 250 rooms, so we don't fetch too many at once, even
-            # if those 250 rooms have less than batch_size state events.
             sql = """
-                SELECT room_id, events FROM %s_rooms
-                ORDER BY events DESC
-                LIMIT 250
-            """ % (
-                TEMP_TABLE,
-            )
-            txn.execute(sql)
-            rooms_to_work_on = txn.fetchall()
-
-            if not rooms_to_work_on:
-                return None
-
-            # Get how many are left to process, so we can give status on how
-            # far we are in processing
-            txn.execute("SELECT COUNT(*) FROM " + TEMP_TABLE + "_rooms")
-            progress["remaining"] = txn.fetchone()[0]
-
-            return rooms_to_work_on
+                    SELECT DISTINCT room_id FROM current_state_events
+                    WHERE room_id > ?
+                    ORDER BY room_id ASC
+                    LIMIT ?
+                """
+            txn.execute(sql, (last_room_id, batch_size))
+            return [r for r, in txn]
 
         rooms_to_work_on = yield self.runInteraction(
-            "populate_stats_temp_read", _get_next_batch
+            "populate_stats_rooms_get_batch", _get_next_batch
         )
 
         # No more rooms -- complete the transaction.
@@ -188,154 +169,28 @@ class StatsStore(StateDeltasStore):
             yield self._end_background_update("populate_stats_process_rooms")
             return 1
 
-        logger.info(
-            "Processing the next %d rooms of %d remaining",
-            len(rooms_to_work_on),
-            progress["remaining"],
-        )
-
-        # Number of state events we've processed by going through each room
-        processed_event_count = 0
-
-        for room_id, event_count in rooms_to_work_on:
-
-            current_state_ids = yield self.get_current_state_ids(room_id)
-
-            join_rules_id = current_state_ids.get((EventTypes.JoinRules, ""))
-            history_visibility_id = current_state_ids.get(
-                (EventTypes.RoomHistoryVisibility, "")
-            )
-            encryption_id = current_state_ids.get((EventTypes.RoomEncryption, ""))
-            name_id = current_state_ids.get((EventTypes.Name, ""))
-            topic_id = current_state_ids.get((EventTypes.Topic, ""))
-            avatar_id = current_state_ids.get((EventTypes.RoomAvatar, ""))
-            canonical_alias_id = current_state_ids.get((EventTypes.CanonicalAlias, ""))
-
-            event_ids = [
-                join_rules_id,
-                history_visibility_id,
-                encryption_id,
-                name_id,
-                topic_id,
-                avatar_id,
-                canonical_alias_id,
-            ]
-
-            state_events = yield self.get_events(
-                [ev for ev in event_ids if ev is not None]
-            )
-
-            def _get_or_none(event_id, arg):
-                event = state_events.get(event_id)
-                if event:
-                    return event.content.get(arg)
-                return None
-
-            yield self.update_room_state(
-                room_id,
-                {
-                    "join_rules": _get_or_none(join_rules_id, "join_rule"),
-                    "history_visibility": _get_or_none(
-                        history_visibility_id, "history_visibility"
-                    ),
-                    "encryption": _get_or_none(encryption_id, "algorithm"),
-                    "name": _get_or_none(name_id, "name"),
-                    "topic": _get_or_none(topic_id, "topic"),
-                    "avatar": _get_or_none(avatar_id, "url"),
-                    "canonical_alias": _get_or_none(canonical_alias_id, "alias"),
-                },
-            )
-
-            now = self.hs.get_reactor().seconds()
-
-            # quantise time to the nearest bucket
-            now = (now // self.stats_bucket_size) * self.stats_bucket_size
-
-            def _fetch_data(txn):
-
-                # Get the current token of the room
-                current_token = self._get_max_stream_id_in_current_state_deltas_txn(txn)
-
-                current_state_events = len(current_state_ids)
-
-                membership_counts = self._get_user_counts_in_room_txn(txn, room_id)
-
-                total_state_events = self._get_total_state_event_counts_txn(
-                    txn, room_id
-                )
-
-                self._update_stats_txn(
-                    txn,
-                    "room",
-                    room_id,
-                    now,
-                    {
-                        "bucket_size": self.stats_bucket_size,
-                        "current_state_events": current_state_events,
-                        "joined_members": membership_counts.get(Membership.JOIN, 0),
-                        "invited_members": membership_counts.get(Membership.INVITE, 0),
-                        "left_members": membership_counts.get(Membership.LEAVE, 0),
-                        "banned_members": membership_counts.get(Membership.BAN, 0),
-                        "state_events": total_state_events,
-                    },
-                )
-                self._simple_insert_txn(
-                    txn,
-                    "room_stats_earliest_token",
-                    {"room_id": room_id, "token": current_token},
-                )
-
-                # We've finished a room. Delete it from the table.
-                self._simple_delete_one_txn(
-                    txn, TEMP_TABLE + "_rooms", {"room_id": room_id}
-                )
+        for room_id in rooms_to_work_on:
+            yield self._calculate_and_set_initial_state_for_room(room_id)
+            progress["last_room_id"] = room_id
 
-            yield self.runInteraction("update_room_stats", _fetch_data)
-
-            # Update the remaining counter.
-            progress["remaining"] -= 1
-            yield self.runInteraction(
-                "populate_stats",
-                self._background_update_progress_txn,
-                "populate_stats_process_rooms",
-                progress,
-            )
-
-            processed_event_count += event_count
-
-            if processed_event_count > batch_size:
-                # Don't process any more rooms, we've hit our batch size.
-                return processed_event_count
+        yield self.runInteraction(
+            "_populate_stats_process_rooms",
+            self._background_update_progress_txn,
+            "populate_stats_process_rooms",
+            progress,
+        )
 
-        return processed_event_count
+        return len(rooms_to_work_on)
 
-    def delete_all_stats(self):
+    def get_stats_positions(self):
         """
-        Delete all statistics records.
+        Returns the stats processor positions.
         """
-
-        def _delete_all_stats_txn(txn):
-            txn.execute("DELETE FROM room_state")
-            txn.execute("DELETE FROM room_stats")
-            txn.execute("DELETE FROM room_stats_earliest_token")
-            txn.execute("DELETE FROM user_stats")
-
-        return self.runInteraction("delete_all_stats", _delete_all_stats_txn)
-
-    def get_stats_stream_pos(self):
         return self._simple_select_one_onecol(
-            table="stats_stream_pos",
+            table="stats_incremental_position",
             keyvalues={},
             retcol="stream_id",
-            desc="stats_stream_pos",
-        )
-
-    def update_stats_stream_pos(self, stream_id):
-        return self._simple_update_one(
-            table="stats_stream_pos",
-            keyvalues={},
-            updatevalues={"stream_id": stream_id},
-            desc="update_stats_stream_pos",
+            desc="stats_incremental_position",
         )
 
     def update_room_state(self, room_id, fields):
@@ -361,42 +216,87 @@ class StatsStore(StateDeltasStore):
                 fields[col] = None
 
         return self._simple_upsert(
-            table="room_state",
+            table="room_stats_state",
             keyvalues={"room_id": room_id},
             values=fields,
             desc="update_room_state",
         )
 
-    def get_deltas_for_room(self, room_id, start, size=100):
+    def get_statistics_for_subject(self, stats_type, stats_id, start, size=100):
         """
-        Get statistics deltas for a given room.
+        Get statistics for a given subject.
 
         Args:
-            room_id (str)
+            stats_type (str): The type of subject
+            stats_id (str): The ID of the subject (e.g. room_id or user_id)
             start (int): Pagination start. Number of entries, not timestamp.
             size (int): How many entries to return.
 
         Returns:
             Deferred[list[dict]], where the dict has the keys of
-            ABSOLUTE_STATS_FIELDS["room"] and "ts".
+            ABSOLUTE_STATS_FIELDS[stats_type],  and "bucket_size" and "end_ts".
         """
-        return self._simple_select_list_paginate(
-            "room_stats",
-            {"room_id": room_id},
-            "ts",
+        return self.runInteraction(
+            "get_statistics_for_subject",
+            self._get_statistics_for_subject_txn,
+            stats_type,
+            stats_id,
             start,
             size,
-            retcols=(list(ABSOLUTE_STATS_FIELDS["room"]) + ["ts"]),
+        )
+
+    def _get_statistics_for_subject_txn(
+        self, txn, stats_type, stats_id, start, size=100
+    ):
+        """
+        Transaction-bound version of L{get_statistics_for_subject}.
+        """
+
+        table, id_col = TYPE_TO_TABLE[stats_type]
+        selected_columns = list(
+            ABSOLUTE_STATS_FIELDS[stats_type] + PER_SLICE_FIELDS[stats_type]
+        )
+
+        slice_list = self._simple_select_list_paginate_txn(
+            txn,
+            table + "_historical",
+            {id_col: stats_id},
+            "end_ts",
+            start,
+            size,
+            retcols=selected_columns + ["bucket_size", "end_ts"],
             order_direction="DESC",
         )
 
-    def get_all_room_state(self):
-        return self._simple_select_list(
-            "room_state", None, retcols=("name", "topic", "canonical_alias")
+        return slice_list
+
+    def get_room_stats_state(self, room_id):
+        """
+        Returns the current room_stats_state for a room.
+
+        Args:
+            room_id (str): The ID of the room to return state for.
+
+        Returns (dict):
+            Dictionary containing these keys:
+                "name", "topic", "canonical_alias", "avatar", "join_rules",
+                "history_visibility"
+        """
+        return self._simple_select_one(
+            "room_stats_state",
+            {"room_id": room_id},
+            retcols=(
+                "name",
+                "topic",
+                "canonical_alias",
+                "avatar",
+                "join_rules",
+                "history_visibility",
+            ),
         )
 
     @cached()
-    def get_earliest_token_for_room_stats(self, room_id):
+    def get_earliest_token_for_stats(self, stats_type, id):
         """
         Fetch the "earliest token". This is used by the room stats delta
         processor to ignore deltas that have been processed between the
@@ -406,79 +306,573 @@ class StatsStore(StateDeltasStore):
         Returns:
             Deferred[int]
         """
+        table, id_col = TYPE_TO_TABLE[stats_type]
+
         return self._simple_select_one_onecol(
-            "room_stats_earliest_token",
-            {"room_id": room_id},
-            retcol="token",
+            "%s_current" % (table,),
+            keyvalues={id_col: id},
+            retcol="completed_delta_stream_id",
             allow_none=True,
         )
 
-    def update_stats(self, stats_type, stats_id, ts, fields):
-        table, id_col = TYPE_TO_ROOM[stats_type]
-        return self._simple_upsert(
-            table=table,
-            keyvalues={id_col: stats_id, "ts": ts},
-            values=fields,
-            desc="update_stats",
+    def bulk_update_stats_delta(self, ts, updates, stream_id):
+        """Bulk update stats tables for a given stream_id and updates the stats
+        incremental position.
+
+        Args:
+            ts (int): Current timestamp in ms
+            updates(dict[str, dict[str, dict[str, Counter]]]): The updates to
+                commit as a mapping stats_type -> stats_id -> field -> delta.
+            stream_id (int): Current position.
+
+        Returns:
+            Deferred
+        """
+
+        def _bulk_update_stats_delta_txn(txn):
+            for stats_type, stats_updates in updates.items():
+                for stats_id, fields in stats_updates.items():
+                    self._update_stats_delta_txn(
+                        txn,
+                        ts=ts,
+                        stats_type=stats_type,
+                        stats_id=stats_id,
+                        fields=fields,
+                        complete_with_stream_id=stream_id,
+                    )
+
+            self._simple_update_one_txn(
+                txn,
+                table="stats_incremental_position",
+                keyvalues={},
+                updatevalues={"stream_id": stream_id},
+            )
+
+        return self.runInteraction(
+            "bulk_update_stats_delta", _bulk_update_stats_delta_txn
         )
 
-    def _update_stats_txn(self, txn, stats_type, stats_id, ts, fields):
-        table, id_col = TYPE_TO_ROOM[stats_type]
-        return self._simple_upsert_txn(
-            txn, table=table, keyvalues={id_col: stats_id, "ts": ts}, values=fields
+    def update_stats_delta(
+        self,
+        ts,
+        stats_type,
+        stats_id,
+        fields,
+        complete_with_stream_id,
+        absolute_field_overrides=None,
+    ):
+        """
+        Updates the statistics for a subject, with a delta (difference/relative
+        change).
+
+        Args:
+            ts (int): timestamp of the change
+            stats_type (str): "room" or "user" – the kind of subject
+            stats_id (str): the subject's ID (room ID or user ID)
+            fields (dict[str, int]): Deltas of stats values.
+            complete_with_stream_id (int, optional):
+                If supplied, converts an incomplete row into a complete row,
+                with the supplied stream_id marked as the stream_id where the
+                row was completed.
+            absolute_field_overrides (dict[str, int]): Current stats values
+                (i.e. not deltas) of absolute fields.
+                Does not work with per-slice fields.
+        """
+
+        return self.runInteraction(
+            "update_stats_delta",
+            self._update_stats_delta_txn,
+            ts,
+            stats_type,
+            stats_id,
+            fields,
+            complete_with_stream_id=complete_with_stream_id,
+            absolute_field_overrides=absolute_field_overrides,
         )
 
-    def update_stats_delta(self, ts, stats_type, stats_id, field, value):
-        def _update_stats_delta(txn):
-            table, id_col = TYPE_TO_ROOM[stats_type]
-
-            sql = (
-                "SELECT * FROM %s"
-                " WHERE %s=? and ts=("
-                "  SELECT MAX(ts) FROM %s"
-                "  WHERE %s=?"
-                ")"
-            ) % (table, id_col, table, id_col)
-            txn.execute(sql, (stats_id, stats_id))
-            rows = self.cursor_to_dict(txn)
-            if len(rows) == 0:
-                # silently skip as we don't have anything to apply a delta to yet.
-                # this tries to minimise any race between the initial sync and
-                # subsequent deltas arriving.
-                return
-
-            current_ts = ts
-            latest_ts = rows[0]["ts"]
-            if current_ts < latest_ts:
-                # This one is in the past, but we're just encountering it now.
-                # Mark it as part of the current bucket.
-                current_ts = latest_ts
-            elif ts != latest_ts:
-                # we have to copy our absolute counters over to the new entry.
-                values = {
-                    key: rows[0][key] for key in ABSOLUTE_STATS_FIELDS[stats_type]
-                }
-                values[id_col] = stats_id
-                values["ts"] = ts
-                values["bucket_size"] = self.stats_bucket_size
-
-                self._simple_insert_txn(txn, table=table, values=values)
-
-            # actually update the new value
-            if stats_type in ABSOLUTE_STATS_FIELDS[stats_type]:
-                self._simple_update_txn(
-                    txn,
-                    table=table,
-                    keyvalues={id_col: stats_id, "ts": current_ts},
-                    updatevalues={field: value},
+    def _update_stats_delta_txn(
+        self,
+        txn,
+        ts,
+        stats_type,
+        stats_id,
+        fields,
+        complete_with_stream_id,
+        absolute_field_overrides=None,
+    ):
+        if absolute_field_overrides is None:
+            absolute_field_overrides = {}
+
+        table, id_col = TYPE_TO_TABLE[stats_type]
+
+        quantised_ts = self.quantise_stats_time(int(ts))
+        end_ts = quantised_ts + self.stats_bucket_size
+
+        # Lets be paranoid and check that all the given field names are known
+        abs_field_names = ABSOLUTE_STATS_FIELDS[stats_type]
+        slice_field_names = PER_SLICE_FIELDS[stats_type]
+        for field in chain(fields.keys(), absolute_field_overrides.keys()):
+            if field not in abs_field_names and field not in slice_field_names:
+                # guard against potential SQL injection dodginess
+                raise ValueError(
+                    "%s is not a recognised field"
+                    " for stats type %s" % (field, stats_type)
                 )
+
+        # Per slice fields do not get added to the _current table
+
+        # This calculates the deltas (`field = field + ?` values)
+        # for absolute fields,
+        # * defaulting to 0 if not specified
+        #     (required for the INSERT part of upserting to work)
+        # * omitting overrides specified in `absolute_field_overrides`
+        deltas_of_absolute_fields = {
+            key: fields.get(key, 0)
+            for key in abs_field_names
+            if key not in absolute_field_overrides
+        }
+
+        # Keep the delta stream ID field up to date
+        absolute_field_overrides = absolute_field_overrides.copy()
+        absolute_field_overrides["completed_delta_stream_id"] = complete_with_stream_id
+
+        # first upsert the `_current` table
+        self._upsert_with_additive_relatives_txn(
+            txn=txn,
+            table=table + "_current",
+            keyvalues={id_col: stats_id},
+            absolutes=absolute_field_overrides,
+            additive_relatives=deltas_of_absolute_fields,
+        )
+
+        per_slice_additive_relatives = {
+            key: fields.get(key, 0) for key in slice_field_names
+        }
+        self._upsert_copy_from_table_with_additive_relatives_txn(
+            txn=txn,
+            into_table=table + "_historical",
+            keyvalues={id_col: stats_id},
+            extra_dst_insvalues={"bucket_size": self.stats_bucket_size},
+            extra_dst_keyvalues={"end_ts": end_ts},
+            additive_relatives=per_slice_additive_relatives,
+            src_table=table + "_current",
+            copy_columns=abs_field_names,
+        )
+
+    def _upsert_with_additive_relatives_txn(
+        self, txn, table, keyvalues, absolutes, additive_relatives
+    ):
+        """Used to update values in the stats tables.
+
+        This is basically a slightly convoluted upsert that *adds* to any
+        existing rows.
+
+        Args:
+            txn
+            table (str): Table name
+            keyvalues (dict[str, any]): Row-identifying key values
+            absolutes (dict[str, any]): Absolute (set) fields
+            additive_relatives (dict[str, int]): Fields that will be added onto
+                if existing row present.
+        """
+        if self.database_engine.can_native_upsert:
+            absolute_updates = [
+                "%(field)s = EXCLUDED.%(field)s" % {"field": field}
+                for field in absolutes.keys()
+            ]
+
+            relative_updates = [
+                "%(field)s = EXCLUDED.%(field)s + %(table)s.%(field)s"
+                % {"table": table, "field": field}
+                for field in additive_relatives.keys()
+            ]
+
+            insert_cols = []
+            qargs = []
+
+            for (key, val) in chain(
+                keyvalues.items(), absolutes.items(), additive_relatives.items()
+            ):
+                insert_cols.append(key)
+                qargs.append(val)
+
+            sql = """
+                INSERT INTO %(table)s (%(insert_cols_cs)s)
+                VALUES (%(insert_vals_qs)s)
+                ON CONFLICT (%(key_columns)s) DO UPDATE SET %(updates)s
+            """ % {
+                "table": table,
+                "insert_cols_cs": ", ".join(insert_cols),
+                "insert_vals_qs": ", ".join(
+                    ["?"] * (len(keyvalues) + len(absolutes) + len(additive_relatives))
+                ),
+                "key_columns": ", ".join(keyvalues),
+                "updates": ", ".join(chain(absolute_updates, relative_updates)),
+            }
+
+            txn.execute(sql, qargs)
+        else:
+            self.database_engine.lock_table(txn, table)
+            retcols = list(chain(absolutes.keys(), additive_relatives.keys()))
+            current_row = self._simple_select_one_txn(
+                txn, table, keyvalues, retcols, allow_none=True
+            )
+            if current_row is None:
+                merged_dict = {**keyvalues, **absolutes, **additive_relatives}
+                self._simple_insert_txn(txn, table, merged_dict)
             else:
-                sql = ("UPDATE %s SET %s=%s+? WHERE %s=? AND ts=?") % (
-                    table,
-                    field,
-                    field,
-                    id_col,
+                for (key, val) in additive_relatives.items():
+                    current_row[key] += val
+                current_row.update(absolutes)
+                self._simple_update_one_txn(txn, table, keyvalues, current_row)
+
+    def _upsert_copy_from_table_with_additive_relatives_txn(
+        self,
+        txn,
+        into_table,
+        keyvalues,
+        extra_dst_keyvalues,
+        extra_dst_insvalues,
+        additive_relatives,
+        src_table,
+        copy_columns,
+    ):
+        """Updates the historic stats table with latest updates.
+
+        This involves copying "absolute" fields from the `_current` table, and
+        adding relative fields to any existing values.
+
+        Args:
+             txn: Transaction
+             into_table (str): The destination table to UPSERT the row into
+             keyvalues (dict[str, any]): Row-identifying key values
+             extra_dst_keyvalues (dict[str, any]): Additional keyvalues
+                for `into_table`.
+             extra_dst_insvalues (dict[str, any]): Additional values to insert
+                on new row creation for `into_table`.
+             additive_relatives (dict[str, any]): Fields that will be added onto
+                if existing row present. (Must be disjoint from copy_columns.)
+             src_table (str): The source table to copy from
+             copy_columns (iterable[str]): The list of columns to copy
+        """
+        if self.database_engine.can_native_upsert:
+            ins_columns = chain(
+                keyvalues,
+                copy_columns,
+                additive_relatives,
+                extra_dst_keyvalues,
+                extra_dst_insvalues,
+            )
+            sel_exprs = chain(
+                keyvalues,
+                copy_columns,
+                (
+                    "?"
+                    for _ in chain(
+                        additive_relatives, extra_dst_keyvalues, extra_dst_insvalues
+                    )
+                ),
+            )
+            keyvalues_where = ("%s = ?" % f for f in keyvalues)
+
+            sets_cc = ("%s = EXCLUDED.%s" % (f, f) for f in copy_columns)
+            sets_ar = (
+                "%s = EXCLUDED.%s + %s.%s" % (f, f, into_table, f)
+                for f in additive_relatives
+            )
+
+            sql = """
+                INSERT INTO %(into_table)s (%(ins_columns)s)
+                SELECT %(sel_exprs)s
+                FROM %(src_table)s
+                WHERE %(keyvalues_where)s
+                ON CONFLICT (%(keyvalues)s)
+                DO UPDATE SET %(sets)s
+            """ % {
+                "into_table": into_table,
+                "ins_columns": ", ".join(ins_columns),
+                "sel_exprs": ", ".join(sel_exprs),
+                "keyvalues_where": " AND ".join(keyvalues_where),
+                "src_table": src_table,
+                "keyvalues": ", ".join(
+                    chain(keyvalues.keys(), extra_dst_keyvalues.keys())
+                ),
+                "sets": ", ".join(chain(sets_cc, sets_ar)),
+            }
+
+            qargs = list(
+                chain(
+                    additive_relatives.values(),
+                    extra_dst_keyvalues.values(),
+                    extra_dst_insvalues.values(),
+                    keyvalues.values(),
                 )
-                txn.execute(sql, (value, stats_id, current_ts))
+            )
+            txn.execute(sql, qargs)
+        else:
+            self.database_engine.lock_table(txn, into_table)
+            src_row = self._simple_select_one_txn(
+                txn, src_table, keyvalues, copy_columns
+            )
+            all_dest_keyvalues = {**keyvalues, **extra_dst_keyvalues}
+            dest_current_row = self._simple_select_one_txn(
+                txn,
+                into_table,
+                keyvalues=all_dest_keyvalues,
+                retcols=list(chain(additive_relatives.keys(), copy_columns)),
+                allow_none=True,
+            )
+
+            if dest_current_row is None:
+                merged_dict = {
+                    **keyvalues,
+                    **extra_dst_keyvalues,
+                    **extra_dst_insvalues,
+                    **src_row,
+                    **additive_relatives,
+                }
+                self._simple_insert_txn(txn, into_table, merged_dict)
+            else:
+                for (key, val) in additive_relatives.items():
+                    src_row[key] = dest_current_row[key] + val
+                self._simple_update_txn(txn, into_table, all_dest_keyvalues, src_row)
+
+    def get_changes_room_total_events_and_bytes(self, min_pos, max_pos):
+        """Fetches the counts of events in the given range of stream IDs.
+
+        Args:
+            min_pos (int)
+            max_pos (int)
+
+        Returns:
+            Deferred[dict[str, dict[str, int]]]: Mapping of room ID to field
+            changes.
+        """
+
+        return self.runInteraction(
+            "stats_incremental_total_events_and_bytes",
+            self.get_changes_room_total_events_and_bytes_txn,
+            min_pos,
+            max_pos,
+        )
 
-        return self.runInteraction("update_stats_delta", _update_stats_delta)
+    def get_changes_room_total_events_and_bytes_txn(self, txn, low_pos, high_pos):
+        """Gets the total_events and total_event_bytes counts for rooms and
+        senders, in a range of stream_orderings (including backfilled events).
+
+        Args:
+            txn
+            low_pos (int): Low stream ordering
+            high_pos (int): High stream ordering
+
+        Returns:
+            tuple[dict[str, dict[str, int]], dict[str, dict[str, int]]]: The
+            room and user deltas for total_events/total_event_bytes in the
+            format of `stats_id` -> fields
+        """
+
+        if low_pos >= high_pos:
+            # nothing to do here.
+            return {}, {}
+
+        if isinstance(self.database_engine, PostgresEngine):
+            new_bytes_expression = "OCTET_LENGTH(json)"
+        else:
+            new_bytes_expression = "LENGTH(CAST(json AS BLOB))"
+
+        sql = """
+            SELECT events.room_id, COUNT(*) AS new_events, SUM(%s) AS new_bytes
+            FROM events INNER JOIN event_json USING (event_id)
+            WHERE (? < stream_ordering AND stream_ordering <= ?)
+                OR (? <= stream_ordering AND stream_ordering <= ?)
+            GROUP BY events.room_id
+        """ % (
+            new_bytes_expression,
+        )
+
+        txn.execute(sql, (low_pos, high_pos, -high_pos, -low_pos))
+
+        room_deltas = {
+            room_id: {"total_events": new_events, "total_event_bytes": new_bytes}
+            for room_id, new_events, new_bytes in txn
+        }
+
+        sql = """
+            SELECT events.sender, COUNT(*) AS new_events, SUM(%s) AS new_bytes
+            FROM events INNER JOIN event_json USING (event_id)
+            WHERE (? < stream_ordering AND stream_ordering <= ?)
+                OR (? <= stream_ordering AND stream_ordering <= ?)
+            GROUP BY events.sender
+        """ % (
+            new_bytes_expression,
+        )
+
+        txn.execute(sql, (low_pos, high_pos, -high_pos, -low_pos))
+
+        user_deltas = {
+            user_id: {"total_events": new_events, "total_event_bytes": new_bytes}
+            for user_id, new_events, new_bytes in txn
+            if self.hs.is_mine_id(user_id)
+        }
+
+        return room_deltas, user_deltas
+
+    @defer.inlineCallbacks
+    def _calculate_and_set_initial_state_for_room(self, room_id):
+        """Calculate and insert an entry into room_stats_current.
+
+        Args:
+            room_id (str)
+
+        Returns:
+            Deferred[tuple[dict, dict, int]]: A tuple of room state, membership
+            counts and stream position.
+        """
+
+        def _fetch_current_state_stats(txn):
+            pos = self.get_room_max_stream_ordering()
+
+            rows = self._simple_select_many_txn(
+                txn,
+                table="current_state_events",
+                column="type",
+                iterable=[
+                    EventTypes.Create,
+                    EventTypes.JoinRules,
+                    EventTypes.RoomHistoryVisibility,
+                    EventTypes.Encryption,
+                    EventTypes.Name,
+                    EventTypes.Topic,
+                    EventTypes.RoomAvatar,
+                    EventTypes.CanonicalAlias,
+                ],
+                keyvalues={"room_id": room_id, "state_key": ""},
+                retcols=["event_id"],
+            )
+
+            event_ids = [row["event_id"] for row in rows]
+
+            txn.execute(
+                """
+                    SELECT membership, count(*) FROM current_state_events
+                    WHERE room_id = ? AND type = 'm.room.member'
+                    GROUP BY membership
+                """,
+                (room_id,),
+            )
+            membership_counts = {membership: cnt for membership, cnt in txn}
+
+            txn.execute(
+                """
+                    SELECT COALESCE(count(*), 0) FROM current_state_events
+                    WHERE room_id = ?
+                """,
+                (room_id,),
+            )
+
+            current_state_events_count, = txn.fetchone()
+
+            users_in_room = self.get_users_in_room_txn(txn, room_id)
+
+            return (
+                event_ids,
+                membership_counts,
+                current_state_events_count,
+                users_in_room,
+                pos,
+            )
+
+        (
+            event_ids,
+            membership_counts,
+            current_state_events_count,
+            users_in_room,
+            pos,
+        ) = yield self.runInteraction(
+            "get_initial_state_for_room", _fetch_current_state_stats
+        )
+
+        state_event_map = yield self.get_events(event_ids, get_prev_content=False)
+
+        room_state = {
+            "join_rules": None,
+            "history_visibility": None,
+            "encryption": None,
+            "name": None,
+            "topic": None,
+            "avatar": None,
+            "canonical_alias": None,
+            "is_federatable": True,
+        }
+
+        for event in state_event_map.values():
+            if event.type == EventTypes.JoinRules:
+                room_state["join_rules"] = event.content.get("join_rule")
+            elif event.type == EventTypes.RoomHistoryVisibility:
+                room_state["history_visibility"] = event.content.get(
+                    "history_visibility"
+                )
+            elif event.type == EventTypes.Encryption:
+                room_state["encryption"] = event.content.get("algorithm")
+            elif event.type == EventTypes.Name:
+                room_state["name"] = event.content.get("name")
+            elif event.type == EventTypes.Topic:
+                room_state["topic"] = event.content.get("topic")
+            elif event.type == EventTypes.RoomAvatar:
+                room_state["avatar"] = event.content.get("url")
+            elif event.type == EventTypes.CanonicalAlias:
+                room_state["canonical_alias"] = event.content.get("alias")
+            elif event.type == EventTypes.Create:
+                room_state["is_federatable"] = (
+                    event.content.get("m.federate", True) is True
+                )
+
+        yield self.update_room_state(room_id, room_state)
+
+        local_users_in_room = [u for u in users_in_room if self.hs.is_mine_id(u)]
+
+        yield self.update_stats_delta(
+            ts=self.clock.time_msec(),
+            stats_type="room",
+            stats_id=room_id,
+            fields={},
+            complete_with_stream_id=pos,
+            absolute_field_overrides={
+                "current_state_events": current_state_events_count,
+                "joined_members": membership_counts.get(Membership.JOIN, 0),
+                "invited_members": membership_counts.get(Membership.INVITE, 0),
+                "left_members": membership_counts.get(Membership.LEAVE, 0),
+                "banned_members": membership_counts.get(Membership.BAN, 0),
+                "local_users_in_room": len(local_users_in_room),
+            },
+        )
+
+    @defer.inlineCallbacks
+    def _calculate_and_set_initial_state_for_user(self, user_id):
+        def _calculate_and_set_initial_state_for_user_txn(txn):
+            pos = self._get_max_stream_id_in_current_state_deltas_txn(txn)
+
+            txn.execute(
+                """
+                SELECT COUNT(distinct room_id) FROM current_state_events
+                    WHERE type = 'm.room.member' AND state_key = ?
+                        AND membership = 'join'
+                """,
+                (user_id,),
+            )
+            count, = txn.fetchone()
+            return count, pos
+
+        joined_rooms, pos = yield self.runInteraction(
+            "calculate_and_set_initial_state_for_user",
+            _calculate_and_set_initial_state_for_user_txn,
+        )
+
+        yield self.update_stats_delta(
+            ts=self.clock.time_msec(),
+            stats_type="user",
+            stats_id=user_id,
+            fields={},
+            complete_with_stream_id=pos,
+            absolute_field_overrides={"joined_rooms": joined_rooms},
+        )
diff --git a/synapse/storage/stream.py b/synapse/storage/stream.py
index 856c2ee8d8..490454f19a 100644
--- a/synapse/storage/stream.py
+++ b/synapse/storage/stream.py
@@ -364,7 +364,7 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
             the chunk of events returned.
         """
         if from_key == to_key:
-            return ([], from_key)
+            return [], from_key
 
         from_id = RoomStreamToken.parse_stream_token(from_key).stream
         to_id = RoomStreamToken.parse_stream_token(to_key).stream
@@ -374,7 +374,7 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
         )
 
         if not has_changed:
-            return ([], from_key)
+            return [], from_key
 
         def f(txn):
             sql = (
@@ -407,7 +407,7 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
             # get.
             key = from_key
 
-        return (ret, key)
+        return ret, key
 
     @defer.inlineCallbacks
     def get_membership_changes_for_user(self, user_id, from_key, to_key):
@@ -496,7 +496,7 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
         """
         # Allow a zero limit here, and no-op.
         if limit == 0:
-            return ([], end_token)
+            return [], end_token
 
         end_token = RoomStreamToken.parse(end_token)
 
@@ -511,7 +511,7 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
         # We want to return the results in ascending order.
         rows.reverse()
 
-        return (rows, token)
+        return rows, token
 
     def get_room_event_after_stream_ordering(self, room_id, stream_ordering):
         """Gets details of the first event in a room at or after a stream ordering
@@ -783,7 +783,7 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
 
         events = yield self.get_events_as_list(event_ids)
 
-        return (upper_bound, events)
+        return upper_bound, events
 
     def get_federation_out_pos(self, typ):
         return self._simple_select_one_onecol(
diff --git a/synapse/storage/transactions.py b/synapse/storage/transactions.py
index b3c3bf55bc..289c117396 100644
--- a/synapse/storage/transactions.py
+++ b/synapse/storage/transactions.py
@@ -165,7 +165,7 @@ class TransactionStore(SQLBaseStore):
             txn,
             table="destinations",
             keyvalues={"destination": destination},
-            retcols=("destination", "retry_last_ts", "retry_interval"),
+            retcols=("destination", "failure_ts", "retry_last_ts", "retry_interval"),
             allow_none=True,
         )
 
@@ -174,12 +174,15 @@ class TransactionStore(SQLBaseStore):
         else:
             return None
 
-    def set_destination_retry_timings(self, destination, retry_last_ts, retry_interval):
+    def set_destination_retry_timings(
+        self, destination, failure_ts, retry_last_ts, retry_interval
+    ):
         """Sets the current retry timings for a given destination.
         Both timings should be zero if retrying is no longer occuring.
 
         Args:
             destination (str)
+            failure_ts (int|None) - when the server started failing (ms since epoch)
             retry_last_ts (int) - time of last retry attempt in unix epoch ms
             retry_interval (int) - how long until next retry in ms
         """
@@ -189,12 +192,13 @@ class TransactionStore(SQLBaseStore):
             "set_destination_retry_timings",
             self._set_destination_retry_timings,
             destination,
+            failure_ts,
             retry_last_ts,
             retry_interval,
         )
 
     def _set_destination_retry_timings(
-        self, txn, destination, retry_last_ts, retry_interval
+        self, txn, destination, failure_ts, retry_last_ts, retry_interval
     ):
 
         if self.database_engine.can_native_upsert:
@@ -202,9 +206,12 @@ class TransactionStore(SQLBaseStore):
             # resetting it) or greater than the existing retry interval.
 
             sql = """
-                INSERT INTO destinations (destination, retry_last_ts, retry_interval)
-                    VALUES (?, ?, ?)
+                INSERT INTO destinations (
+                    destination, failure_ts, retry_last_ts, retry_interval
+                )
+                    VALUES (?, ?, ?, ?)
                 ON CONFLICT (destination) DO UPDATE SET
+                        failure_ts = EXCLUDED.failure_ts,
                         retry_last_ts = EXCLUDED.retry_last_ts,
                         retry_interval = EXCLUDED.retry_interval
                     WHERE
@@ -212,7 +219,7 @@ class TransactionStore(SQLBaseStore):
                         OR destinations.retry_interval < EXCLUDED.retry_interval
             """
 
-            txn.execute(sql, (destination, retry_last_ts, retry_interval))
+            txn.execute(sql, (destination, failure_ts, retry_last_ts, retry_interval))
 
             return
 
@@ -225,7 +232,7 @@ class TransactionStore(SQLBaseStore):
             txn,
             table="destinations",
             keyvalues={"destination": destination},
-            retcols=("retry_last_ts", "retry_interval"),
+            retcols=("failure_ts", "retry_last_ts", "retry_interval"),
             allow_none=True,
         )
 
@@ -235,6 +242,7 @@ class TransactionStore(SQLBaseStore):
                 table="destinations",
                 values={
                     "destination": destination,
+                    "failure_ts": failure_ts,
                     "retry_last_ts": retry_last_ts,
                     "retry_interval": retry_interval,
                 },
@@ -245,31 +253,12 @@ class TransactionStore(SQLBaseStore):
                 "destinations",
                 keyvalues={"destination": destination},
                 updatevalues={
+                    "failure_ts": failure_ts,
                     "retry_last_ts": retry_last_ts,
                     "retry_interval": retry_interval,
                 },
             )
 
-    def get_destinations_needing_retry(self):
-        """Get all destinations which are due a retry for sending a transaction.
-
-        Returns:
-            list: A list of dicts
-        """
-
-        return self.runInteraction(
-            "get_destinations_needing_retry", self._get_destinations_needing_retry
-        )
-
-    def _get_destinations_needing_retry(self, txn):
-        query = (
-            "SELECT * FROM destinations"
-            " WHERE retry_last_ts > 0 and retry_next_ts < ?"
-        )
-
-        txn.execute(query, (self._clock.time_msec(),))
-        return self.cursor_to_dict(txn)
-
     def _start_cleanup_transactions(self):
         return run_as_background_process(
             "cleanup_transactions", self._cleanup_transactions
diff --git a/synapse/storage/util/id_generators.py b/synapse/storage/util/id_generators.py
index f1c8d99419..cbb0a4810a 100644
--- a/synapse/storage/util/id_generators.py
+++ b/synapse/storage/util/id_generators.py
@@ -195,6 +195,6 @@ class ChainedIdGenerator(object):
         with self._lock:
             if self._unfinished_ids:
                 stream_id, chained_id = self._unfinished_ids[0]
-                return (stream_id - 1, chained_id)
+                return stream_id - 1, chained_id
 
-            return (self._current_max, self.chained_generator.get_current_token())
+            return self._current_max, self.chained_generator.get_current_token()