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-rw-r--r--synapse/storage/__init__.py6
-rw-r--r--synapse/storage/_base.py88
-rw-r--r--synapse/storage/appservice.py4
-rw-r--r--synapse/storage/deviceinbox.py2
-rw-r--r--synapse/storage/event_federation.py6
-rw-r--r--synapse/storage/events.py288
-rw-r--r--synapse/storage/events_bg_updates.py401
-rw-r--r--synapse/storage/events_worker.py129
-rw-r--r--synapse/storage/keys.py90
-rw-r--r--synapse/storage/registration.py16
-rw-r--r--synapse/storage/relations.py476
-rw-r--r--synapse/storage/roommember.py21
-rw-r--r--synapse/storage/schema/delta/54/account_validity_with_renewal.sql (renamed from synapse/storage/schema/delta/54/account_validity.sql)3
-rw-r--r--synapse/storage/schema/delta/54/add_validity_to_server_keys.sql23
-rw-r--r--synapse/storage/schema/delta/54/delete_forward_extremities.sql23
-rw-r--r--synapse/storage/schema/delta/54/relations.sql27
-rw-r--r--synapse/storage/schema/delta/54/stats.sql80
-rw-r--r--synapse/storage/schema/delta/54/stats2.sql28
-rw-r--r--synapse/storage/search.py4
-rw-r--r--synapse/storage/state_deltas.py30
-rw-r--r--synapse/storage/stats.py468
-rw-r--r--synapse/storage/stream.py212
22 files changed, 2095 insertions, 330 deletions
diff --git a/synapse/storage/__init__.py b/synapse/storage/__init__.py
index c432041b4e..71316f7d09 100644
--- a/synapse/storage/__init__.py
+++ b/synapse/storage/__init__.py
@@ -36,6 +36,7 @@ from .engines import PostgresEngine
 from .event_federation import EventFederationStore
 from .event_push_actions import EventPushActionsStore
 from .events import EventsStore
+from .events_bg_updates import EventsBackgroundUpdatesStore
 from .filtering import FilteringStore
 from .group_server import GroupServerStore
 from .keys import KeyStore
@@ -49,11 +50,13 @@ from .pusher import PusherStore
 from .receipts import ReceiptsStore
 from .registration import RegistrationStore
 from .rejections import RejectionsStore
+from .relations import RelationsStore
 from .room import RoomStore
 from .roommember import RoomMemberStore
 from .search import SearchStore
 from .signatures import SignatureStore
 from .state import StateStore
+from .stats import StatsStore
 from .stream import StreamStore
 from .tags import TagsStore
 from .transactions import TransactionStore
@@ -64,6 +67,7 @@ logger = logging.getLogger(__name__)
 
 
 class DataStore(
+    EventsBackgroundUpdatesStore,
     RoomMemberStore,
     RoomStore,
     RegistrationStore,
@@ -99,6 +103,8 @@ class DataStore(
     GroupServerStore,
     UserErasureStore,
     MonthlyActiveUsersStore,
+    StatsStore,
+    RelationsStore,
 ):
     def __init__(self, db_conn, hs):
         self.hs = hs
diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index 983ce026e1..52891bb9eb 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -1,5 +1,7 @@
 # -*- coding: utf-8 -*-
 # Copyright 2014-2016 OpenMarket Ltd
+# Copyright 2017-2018 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.
@@ -14,6 +16,7 @@
 # limitations under the License.
 import itertools
 import logging
+import random
 import sys
 import threading
 import time
@@ -227,6 +230,8 @@ class SQLBaseStore(object):
         # A set of tables that are not safe to use native upserts in.
         self._unsafe_to_upsert_tables = set(UNIQUE_INDEX_BACKGROUND_UPDATES.keys())
 
+        self._account_validity = self.hs.config.account_validity
+
         # We add the user_directory_search table to the blacklist on SQLite
         # because the existing search table does not have an index, making it
         # unsafe to use native upserts.
@@ -243,6 +248,16 @@ class SQLBaseStore(object):
                 self._check_safe_to_upsert,
             )
 
+        self.rand = random.SystemRandom()
+
+        if self._account_validity.enabled:
+            self._clock.call_later(
+                0.0,
+                run_as_background_process,
+                "account_validity_set_expiration_dates",
+                self._set_expiration_date_when_missing,
+            )
+
     @defer.inlineCallbacks
     def _check_safe_to_upsert(self):
         """
@@ -275,6 +290,67 @@ class SQLBaseStore(object):
                 self._check_safe_to_upsert,
             )
 
+    @defer.inlineCallbacks
+    def _set_expiration_date_when_missing(self):
+        """
+        Retrieves the list of registered users that don't have an expiration date, and
+        adds an expiration date for each of them.
+        """
+
+        def select_users_with_no_expiration_date_txn(txn):
+            """Retrieves the list of registered users with no expiration date from the
+            database.
+            """
+            sql = (
+                "SELECT users.name FROM users"
+                " LEFT JOIN account_validity ON (users.name = account_validity.user_id)"
+                " WHERE account_validity.user_id is NULL;"
+            )
+            txn.execute(sql, [])
+
+            res = self.cursor_to_dict(txn)
+            if res:
+                for user in res:
+                    self.set_expiration_date_for_user_txn(
+                        txn,
+                        user["name"],
+                        use_delta=True,
+                    )
+
+        yield self.runInteraction(
+            "get_users_with_no_expiration_date",
+            select_users_with_no_expiration_date_txn,
+        )
+
+    def set_expiration_date_for_user_txn(self, txn, user_id, use_delta=False):
+        """Sets an expiration date to the account with the given user ID.
+
+        Args:
+             user_id (str): User ID to set an expiration date for.
+             use_delta (bool): If set to False, the expiration date for the user will be
+                now + validity period. If set to True, this expiration date will be a
+                random value in the [now + period - d ; now + period] range, d being a
+                delta equal to 10% of the validity period.
+        """
+        now_ms = self._clock.time_msec()
+        expiration_ts = now_ms + self._account_validity.period
+
+        if use_delta:
+            expiration_ts = self.rand.randrange(
+                expiration_ts - self._account_validity.startup_job_max_delta,
+                expiration_ts,
+            )
+
+        self._simple_insert_txn(
+            txn,
+            "account_validity",
+            values={
+                "user_id": user_id,
+                "expiration_ts_ms": expiration_ts,
+                "email_sent": False,
+            },
+        )
+
     def start_profiling(self):
         self._previous_loop_ts = self._clock.time_msec()
 
@@ -1203,7 +1279,8 @@ class SQLBaseStore(object):
             " AND ".join("%s = ?" % (k,) for k in keyvalues),
         )
 
-        return txn.execute(sql, list(keyvalues.values()))
+        txn.execute(sql, list(keyvalues.values()))
+        return txn.rowcount
 
     def _simple_delete_many(self, table, column, iterable, keyvalues, desc):
         return self.runInteraction(
@@ -1222,9 +1299,12 @@ class SQLBaseStore(object):
             column : column name to test for inclusion against `iterable`
             iterable : list
             keyvalues : dict of column names and values to select the rows with
+
+        Returns:
+            int: Number rows deleted
         """
         if not iterable:
-            return
+            return 0
 
         sql = "DELETE FROM %s" % table
 
@@ -1239,7 +1319,9 @@ class SQLBaseStore(object):
 
         if clauses:
             sql = "%s WHERE %s" % (sql, " AND ".join(clauses))
-        return txn.execute(sql, values)
+        txn.execute(sql, values)
+
+        return txn.rowcount
 
     def _get_cache_dict(
         self, db_conn, table, entity_column, stream_column, max_value, limit=100000
diff --git a/synapse/storage/appservice.py b/synapse/storage/appservice.py
index 6092f600ba..eb329ebd8b 100644
--- a/synapse/storage/appservice.py
+++ b/synapse/storage/appservice.py
@@ -302,7 +302,7 @@ class ApplicationServiceTransactionWorkerStore(
 
         event_ids = json.loads(entry["event_ids"])
 
-        events = yield self._get_events(event_ids)
+        events = yield self.get_events_as_list(event_ids)
 
         defer.returnValue(
             AppServiceTransaction(service=service, id=entry["txn_id"], events=events)
@@ -358,7 +358,7 @@ class ApplicationServiceTransactionWorkerStore(
             "get_new_events_for_appservice", get_new_events_for_appservice_txn
         )
 
-        events = yield self._get_events(event_ids)
+        events = yield self.get_events_as_list(event_ids)
 
         defer.returnValue((upper_bound, events))
 
diff --git a/synapse/storage/deviceinbox.py b/synapse/storage/deviceinbox.py
index fed4ea3610..9b0a99cb49 100644
--- a/synapse/storage/deviceinbox.py
+++ b/synapse/storage/deviceinbox.py
@@ -118,7 +118,7 @@ class DeviceInboxWorkerStore(SQLBaseStore):
         defer.returnValue(count)
 
     def get_new_device_msgs_for_remote(
-        self, destination, last_stream_id, current_stream_id, limit=100
+        self, destination, last_stream_id, current_stream_id, limit
     ):
         """
         Args:
diff --git a/synapse/storage/event_federation.py b/synapse/storage/event_federation.py
index 956f876572..09e39c2c28 100644
--- a/synapse/storage/event_federation.py
+++ b/synapse/storage/event_federation.py
@@ -45,7 +45,7 @@ class EventFederationWorkerStore(EventsWorkerStore, SignatureWorkerStore, SQLBas
         """
         return self.get_auth_chain_ids(
             event_ids, include_given=include_given
-        ).addCallback(self._get_events)
+        ).addCallback(self.get_events_as_list)
 
     def get_auth_chain_ids(self, event_ids, include_given=False):
         """Get auth events for given event_ids. The events *must* be state events.
@@ -316,7 +316,7 @@ class EventFederationWorkerStore(EventsWorkerStore, SignatureWorkerStore, SQLBas
                 event_list,
                 limit,
             )
-            .addCallback(self._get_events)
+            .addCallback(self.get_events_as_list)
             .addCallback(lambda l: sorted(l, key=lambda e: -e.depth))
         )
 
@@ -382,7 +382,7 @@ class EventFederationWorkerStore(EventsWorkerStore, SignatureWorkerStore, SQLBas
             latest_events,
             limit,
         )
-        events = yield self._get_events(ids)
+        events = yield self.get_events_as_list(ids)
         defer.returnValue(events)
 
     def _get_missing_events(self, txn, room_id, earliest_events, latest_events, limit):
diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index 7a7f841c6c..f9162be9b9 100644
--- a/synapse/storage/events.py
+++ b/synapse/storage/events.py
@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 # Copyright 2014-2016 OpenMarket Ltd
-# Copyright 2018 New Vector Ltd
+# 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.
@@ -219,41 +220,11 @@ class EventsStore(
     EventsWorkerStore,
     BackgroundUpdateStore,
 ):
-    EVENT_ORIGIN_SERVER_TS_NAME = "event_origin_server_ts"
-    EVENT_FIELDS_SENDER_URL_UPDATE_NAME = "event_fields_sender_url"
 
     def __init__(self, db_conn, hs):
         super(EventsStore, self).__init__(db_conn, hs)
-        self.register_background_update_handler(
-            self.EVENT_ORIGIN_SERVER_TS_NAME, self._background_reindex_origin_server_ts
-        )
-        self.register_background_update_handler(
-            self.EVENT_FIELDS_SENDER_URL_UPDATE_NAME,
-            self._background_reindex_fields_sender,
-        )
-
-        self.register_background_index_update(
-            "event_contains_url_index",
-            index_name="event_contains_url_index",
-            table="events",
-            columns=["room_id", "topological_ordering", "stream_ordering"],
-            where_clause="contains_url = true AND outlier = false",
-        )
-
-        # an event_id index on event_search is useful for the purge_history
-        # api. Plus it means we get to enforce some integrity with a UNIQUE
-        # clause
-        self.register_background_index_update(
-            "event_search_event_id_idx",
-            index_name="event_search_event_id_idx",
-            table="event_search",
-            columns=["event_id"],
-            unique=True,
-            psql_only=True,
-        )
 
         self._event_persist_queue = _EventPeristenceQueue()
-
         self._state_resolution_handler = hs.get_state_resolution_handler()
 
     @defer.inlineCallbacks
@@ -554,10 +525,18 @@ class EventsStore(
             e_id for event in new_events for e_id in event.prev_event_ids()
         )
 
-        # Finally, remove any events which are prev_events of any existing events.
+        # Remove any events which are prev_events of any existing events.
         existing_prevs = yield self._get_events_which_are_prevs(result)
         result.difference_update(existing_prevs)
 
+        # Finally handle the case where the new events have soft-failed prev
+        # events. If they do we need to remove them and their prev events,
+        # otherwise we end up with dangling extremities.
+        existing_prevs = yield self._get_prevs_before_rejected(
+            e_id for event in new_events for e_id in event.prev_event_ids()
+        )
+        result.difference_update(existing_prevs)
+
         defer.returnValue(result)
 
     @defer.inlineCallbacks
@@ -573,12 +552,13 @@ class EventsStore(
         """
         results = []
 
-        def _get_events(txn, batch):
+        def _get_events_which_are_prevs_txn(txn, batch):
             sql = """
-            SELECT prev_event_id
+            SELECT prev_event_id, internal_metadata
             FROM event_edges
                 INNER JOIN events USING (event_id)
                 LEFT JOIN rejections USING (event_id)
+                LEFT JOIN event_json USING (event_id)
             WHERE
                 prev_event_id IN (%s)
                 AND NOT events.outlier
@@ -588,14 +568,86 @@ class EventsStore(
             )
 
             txn.execute(sql, batch)
-            results.extend(r[0] for r in txn)
+            results.extend(
+                r[0]
+                for r in txn
+                if not json.loads(r[1]).get("soft_failed")
+            )
 
         for chunk in batch_iter(event_ids, 100):
-            yield self.runInteraction("_get_events_which_are_prevs", _get_events, chunk)
+            yield self.runInteraction(
+                "_get_events_which_are_prevs",
+                _get_events_which_are_prevs_txn,
+                chunk,
+            )
 
         defer.returnValue(results)
 
     @defer.inlineCallbacks
+    def _get_prevs_before_rejected(self, event_ids):
+        """Get soft-failed ancestors to remove from the extremities.
+
+        Given a set of events, find all those that have been soft-failed or
+        rejected. Returns those soft failed/rejected events and their prev
+        events (whether soft-failed/rejected or not), and recurses up the
+        prev-event graph until it finds no more soft-failed/rejected events.
+
+        This is used to find extremities that are ancestors of new events, but
+        are separated by soft failed events.
+
+        Args:
+            event_ids (Iterable[str]): Events to find prev events for. Note
+                that these must have already been persisted.
+
+        Returns:
+            Deferred[set[str]]
+        """
+
+        # The set of event_ids to return. This includes all soft-failed events
+        # and their prev events.
+        existing_prevs = set()
+
+        def _get_prevs_before_rejected_txn(txn, batch):
+            to_recursively_check = batch
+
+            while to_recursively_check:
+                sql = """
+                SELECT
+                    event_id, prev_event_id, internal_metadata,
+                    rejections.event_id IS NOT NULL
+                FROM event_edges
+                    INNER JOIN events USING (event_id)
+                    LEFT JOIN rejections USING (event_id)
+                    LEFT JOIN event_json USING (event_id)
+                WHERE
+                    event_id IN (%s)
+                    AND NOT events.outlier
+                """ % (
+                    ",".join("?" for _ in to_recursively_check),
+                )
+
+                txn.execute(sql, to_recursively_check)
+                to_recursively_check = []
+
+                for event_id, prev_event_id, metadata, rejected in txn:
+                    if prev_event_id in existing_prevs:
+                        continue
+
+                    soft_failed = json.loads(metadata).get("soft_failed")
+                    if soft_failed or rejected:
+                        to_recursively_check.append(prev_event_id)
+                        existing_prevs.add(prev_event_id)
+
+        for chunk in batch_iter(event_ids, 100):
+            yield self.runInteraction(
+                "_get_prevs_before_rejected",
+                _get_prevs_before_rejected_txn,
+                chunk,
+            )
+
+        defer.returnValue(existing_prevs)
+
+    @defer.inlineCallbacks
     def _get_new_state_after_events(
         self, room_id, events_context, old_latest_event_ids, new_latest_event_ids
     ):
@@ -1325,6 +1377,9 @@ class EventsStore(
                     txn, event.room_id, event.redacts
                 )
 
+                # Remove from relations table.
+                self._handle_redaction(txn, event.redacts)
+
         # Update the event_forward_extremities, event_backward_extremities and
         # event_edges tables.
         self._handle_mult_prev_events(
@@ -1351,6 +1406,8 @@ class EventsStore(
                 # Insert into the event_search table.
                 self._store_guest_access_txn(txn, event)
 
+            self._handle_event_relations(txn, event)
+
         # Insert into the room_memberships table.
         self._store_room_members_txn(
             txn,
@@ -1493,153 +1550,6 @@ class EventsStore(
         ret = yield self.runInteraction("count_daily_active_rooms", _count)
         defer.returnValue(ret)
 
-    @defer.inlineCallbacks
-    def _background_reindex_fields_sender(self, progress, batch_size):
-        target_min_stream_id = progress["target_min_stream_id_inclusive"]
-        max_stream_id = progress["max_stream_id_exclusive"]
-        rows_inserted = progress.get("rows_inserted", 0)
-
-        INSERT_CLUMP_SIZE = 1000
-
-        def reindex_txn(txn):
-            sql = (
-                "SELECT stream_ordering, event_id, json FROM events"
-                " INNER JOIN event_json USING (event_id)"
-                " WHERE ? <= stream_ordering AND stream_ordering < ?"
-                " ORDER BY stream_ordering DESC"
-                " LIMIT ?"
-            )
-
-            txn.execute(sql, (target_min_stream_id, max_stream_id, batch_size))
-
-            rows = txn.fetchall()
-            if not rows:
-                return 0
-
-            min_stream_id = rows[-1][0]
-
-            update_rows = []
-            for row in rows:
-                try:
-                    event_id = row[1]
-                    event_json = json.loads(row[2])
-                    sender = event_json["sender"]
-                    content = event_json["content"]
-
-                    contains_url = "url" in content
-                    if contains_url:
-                        contains_url &= isinstance(content["url"], text_type)
-                except (KeyError, AttributeError):
-                    # If the event is missing a necessary field then
-                    # skip over it.
-                    continue
-
-                update_rows.append((sender, contains_url, event_id))
-
-            sql = "UPDATE events SET sender = ?, contains_url = ? WHERE event_id = ?"
-
-            for index in range(0, len(update_rows), INSERT_CLUMP_SIZE):
-                clump = update_rows[index : index + INSERT_CLUMP_SIZE]
-                txn.executemany(sql, clump)
-
-            progress = {
-                "target_min_stream_id_inclusive": target_min_stream_id,
-                "max_stream_id_exclusive": min_stream_id,
-                "rows_inserted": rows_inserted + len(rows),
-            }
-
-            self._background_update_progress_txn(
-                txn, self.EVENT_FIELDS_SENDER_URL_UPDATE_NAME, progress
-            )
-
-            return len(rows)
-
-        result = yield self.runInteraction(
-            self.EVENT_FIELDS_SENDER_URL_UPDATE_NAME, reindex_txn
-        )
-
-        if not result:
-            yield self._end_background_update(self.EVENT_FIELDS_SENDER_URL_UPDATE_NAME)
-
-        defer.returnValue(result)
-
-    @defer.inlineCallbacks
-    def _background_reindex_origin_server_ts(self, progress, batch_size):
-        target_min_stream_id = progress["target_min_stream_id_inclusive"]
-        max_stream_id = progress["max_stream_id_exclusive"]
-        rows_inserted = progress.get("rows_inserted", 0)
-
-        INSERT_CLUMP_SIZE = 1000
-
-        def reindex_search_txn(txn):
-            sql = (
-                "SELECT stream_ordering, event_id FROM events"
-                " WHERE ? <= stream_ordering AND stream_ordering < ?"
-                " ORDER BY stream_ordering DESC"
-                " LIMIT ?"
-            )
-
-            txn.execute(sql, (target_min_stream_id, max_stream_id, batch_size))
-
-            rows = txn.fetchall()
-            if not rows:
-                return 0
-
-            min_stream_id = rows[-1][0]
-            event_ids = [row[1] for row in rows]
-
-            rows_to_update = []
-
-            chunks = [event_ids[i : i + 100] for i in range(0, len(event_ids), 100)]
-            for chunk in chunks:
-                ev_rows = self._simple_select_many_txn(
-                    txn,
-                    table="event_json",
-                    column="event_id",
-                    iterable=chunk,
-                    retcols=["event_id", "json"],
-                    keyvalues={},
-                )
-
-                for row in ev_rows:
-                    event_id = row["event_id"]
-                    event_json = json.loads(row["json"])
-                    try:
-                        origin_server_ts = event_json["origin_server_ts"]
-                    except (KeyError, AttributeError):
-                        # If the event is missing a necessary field then
-                        # skip over it.
-                        continue
-
-                    rows_to_update.append((origin_server_ts, event_id))
-
-            sql = "UPDATE events SET origin_server_ts = ? WHERE event_id = ?"
-
-            for index in range(0, len(rows_to_update), INSERT_CLUMP_SIZE):
-                clump = rows_to_update[index : index + INSERT_CLUMP_SIZE]
-                txn.executemany(sql, clump)
-
-            progress = {
-                "target_min_stream_id_inclusive": target_min_stream_id,
-                "max_stream_id_exclusive": min_stream_id,
-                "rows_inserted": rows_inserted + len(rows_to_update),
-            }
-
-            self._background_update_progress_txn(
-                txn, self.EVENT_ORIGIN_SERVER_TS_NAME, progress
-            )
-
-            return len(rows_to_update)
-
-        result = yield self.runInteraction(
-            self.EVENT_ORIGIN_SERVER_TS_NAME, reindex_search_txn
-        )
-
-        if not result:
-            yield self._end_background_update(self.EVENT_ORIGIN_SERVER_TS_NAME)
-
-        defer.returnValue(result)
-
     def get_current_backfill_token(self):
         """The current minimum token that backfilled events have reached"""
         return -self._backfill_id_gen.get_current_token()
@@ -1655,10 +1565,11 @@ class EventsStore(
         def get_all_new_forward_event_rows(txn):
             sql = (
                 "SELECT e.stream_ordering, e.event_id, e.room_id, e.type,"
-                " state_key, redacts"
+                " state_key, redacts, relates_to_id"
                 " FROM events AS e"
                 " LEFT JOIN redactions USING (event_id)"
                 " LEFT JOIN state_events USING (event_id)"
+                " LEFT JOIN event_relations USING (event_id)"
                 " WHERE ? < stream_ordering AND stream_ordering <= ?"
                 " ORDER BY stream_ordering ASC"
                 " LIMIT ?"
@@ -1673,11 +1584,12 @@ class EventsStore(
 
             sql = (
                 "SELECT event_stream_ordering, e.event_id, e.room_id, e.type,"
-                " state_key, redacts"
+                " state_key, redacts, relates_to_id"
                 " FROM events AS e"
                 " INNER JOIN ex_outlier_stream USING (event_id)"
                 " LEFT JOIN redactions USING (event_id)"
                 " LEFT JOIN state_events USING (event_id)"
+                " LEFT JOIN event_relations USING (event_id)"
                 " WHERE ? < event_stream_ordering"
                 " AND event_stream_ordering <= ?"
                 " ORDER BY event_stream_ordering DESC"
@@ -1698,10 +1610,11 @@ class EventsStore(
         def get_all_new_backfill_event_rows(txn):
             sql = (
                 "SELECT -e.stream_ordering, e.event_id, e.room_id, e.type,"
-                " state_key, redacts"
+                " state_key, redacts, relates_to_id"
                 " FROM events AS e"
                 " LEFT JOIN redactions USING (event_id)"
                 " LEFT JOIN state_events USING (event_id)"
+                " LEFT JOIN event_relations USING (event_id)"
                 " WHERE ? > stream_ordering AND stream_ordering >= ?"
                 " ORDER BY stream_ordering ASC"
                 " LIMIT ?"
@@ -1716,11 +1629,12 @@ class EventsStore(
 
             sql = (
                 "SELECT -event_stream_ordering, e.event_id, e.room_id, e.type,"
-                " state_key, redacts"
+                " state_key, redacts, relates_to_id"
                 " FROM events AS e"
                 " INNER JOIN ex_outlier_stream USING (event_id)"
                 " LEFT JOIN redactions USING (event_id)"
                 " LEFT JOIN state_events USING (event_id)"
+                " LEFT JOIN event_relations USING (event_id)"
                 " WHERE ? > event_stream_ordering"
                 " AND event_stream_ordering >= ?"
                 " ORDER BY event_stream_ordering DESC"
diff --git a/synapse/storage/events_bg_updates.py b/synapse/storage/events_bg_updates.py
new file mode 100644
index 0000000000..75c1935bf3
--- /dev/null
+++ b/synapse/storage/events_bg_updates.py
@@ -0,0 +1,401 @@
+# -*- coding: utf-8 -*-
+# 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.
+
+import logging
+
+from six import text_type
+
+from canonicaljson import json
+
+from twisted.internet import defer
+
+from synapse.storage.background_updates import BackgroundUpdateStore
+
+logger = logging.getLogger(__name__)
+
+
+class EventsBackgroundUpdatesStore(BackgroundUpdateStore):
+
+    EVENT_ORIGIN_SERVER_TS_NAME = "event_origin_server_ts"
+    EVENT_FIELDS_SENDER_URL_UPDATE_NAME = "event_fields_sender_url"
+    DELETE_SOFT_FAILED_EXTREMITIES = "delete_soft_failed_extremities"
+
+    def __init__(self, db_conn, hs):
+        super(EventsBackgroundUpdatesStore, self).__init__(db_conn, hs)
+
+        self.register_background_update_handler(
+            self.EVENT_ORIGIN_SERVER_TS_NAME, self._background_reindex_origin_server_ts
+        )
+        self.register_background_update_handler(
+            self.EVENT_FIELDS_SENDER_URL_UPDATE_NAME,
+            self._background_reindex_fields_sender,
+        )
+
+        self.register_background_index_update(
+            "event_contains_url_index",
+            index_name="event_contains_url_index",
+            table="events",
+            columns=["room_id", "topological_ordering", "stream_ordering"],
+            where_clause="contains_url = true AND outlier = false",
+        )
+
+        # an event_id index on event_search is useful for the purge_history
+        # api. Plus it means we get to enforce some integrity with a UNIQUE
+        # clause
+        self.register_background_index_update(
+            "event_search_event_id_idx",
+            index_name="event_search_event_id_idx",
+            table="event_search",
+            columns=["event_id"],
+            unique=True,
+            psql_only=True,
+        )
+
+        self.register_background_update_handler(
+            self.DELETE_SOFT_FAILED_EXTREMITIES,
+            self._cleanup_extremities_bg_update,
+        )
+
+    @defer.inlineCallbacks
+    def _background_reindex_fields_sender(self, progress, batch_size):
+        target_min_stream_id = progress["target_min_stream_id_inclusive"]
+        max_stream_id = progress["max_stream_id_exclusive"]
+        rows_inserted = progress.get("rows_inserted", 0)
+
+        INSERT_CLUMP_SIZE = 1000
+
+        def reindex_txn(txn):
+            sql = (
+                "SELECT stream_ordering, event_id, json FROM events"
+                " INNER JOIN event_json USING (event_id)"
+                " WHERE ? <= stream_ordering AND stream_ordering < ?"
+                " ORDER BY stream_ordering DESC"
+                " LIMIT ?"
+            )
+
+            txn.execute(sql, (target_min_stream_id, max_stream_id, batch_size))
+
+            rows = txn.fetchall()
+            if not rows:
+                return 0
+
+            min_stream_id = rows[-1][0]
+
+            update_rows = []
+            for row in rows:
+                try:
+                    event_id = row[1]
+                    event_json = json.loads(row[2])
+                    sender = event_json["sender"]
+                    content = event_json["content"]
+
+                    contains_url = "url" in content
+                    if contains_url:
+                        contains_url &= isinstance(content["url"], text_type)
+                except (KeyError, AttributeError):
+                    # If the event is missing a necessary field then
+                    # skip over it.
+                    continue
+
+                update_rows.append((sender, contains_url, event_id))
+
+            sql = "UPDATE events SET sender = ?, contains_url = ? WHERE event_id = ?"
+
+            for index in range(0, len(update_rows), INSERT_CLUMP_SIZE):
+                clump = update_rows[index : index + INSERT_CLUMP_SIZE]
+                txn.executemany(sql, clump)
+
+            progress = {
+                "target_min_stream_id_inclusive": target_min_stream_id,
+                "max_stream_id_exclusive": min_stream_id,
+                "rows_inserted": rows_inserted + len(rows),
+            }
+
+            self._background_update_progress_txn(
+                txn, self.EVENT_FIELDS_SENDER_URL_UPDATE_NAME, progress
+            )
+
+            return len(rows)
+
+        result = yield self.runInteraction(
+            self.EVENT_FIELDS_SENDER_URL_UPDATE_NAME, reindex_txn
+        )
+
+        if not result:
+            yield self._end_background_update(self.EVENT_FIELDS_SENDER_URL_UPDATE_NAME)
+
+        defer.returnValue(result)
+
+    @defer.inlineCallbacks
+    def _background_reindex_origin_server_ts(self, progress, batch_size):
+        target_min_stream_id = progress["target_min_stream_id_inclusive"]
+        max_stream_id = progress["max_stream_id_exclusive"]
+        rows_inserted = progress.get("rows_inserted", 0)
+
+        INSERT_CLUMP_SIZE = 1000
+
+        def reindex_search_txn(txn):
+            sql = (
+                "SELECT stream_ordering, event_id FROM events"
+                " WHERE ? <= stream_ordering AND stream_ordering < ?"
+                " ORDER BY stream_ordering DESC"
+                " LIMIT ?"
+            )
+
+            txn.execute(sql, (target_min_stream_id, max_stream_id, batch_size))
+
+            rows = txn.fetchall()
+            if not rows:
+                return 0
+
+            min_stream_id = rows[-1][0]
+            event_ids = [row[1] for row in rows]
+
+            rows_to_update = []
+
+            chunks = [event_ids[i : i + 100] for i in range(0, len(event_ids), 100)]
+            for chunk in chunks:
+                ev_rows = self._simple_select_many_txn(
+                    txn,
+                    table="event_json",
+                    column="event_id",
+                    iterable=chunk,
+                    retcols=["event_id", "json"],
+                    keyvalues={},
+                )
+
+                for row in ev_rows:
+                    event_id = row["event_id"]
+                    event_json = json.loads(row["json"])
+                    try:
+                        origin_server_ts = event_json["origin_server_ts"]
+                    except (KeyError, AttributeError):
+                        # If the event is missing a necessary field then
+                        # skip over it.
+                        continue
+
+                    rows_to_update.append((origin_server_ts, event_id))
+
+            sql = "UPDATE events SET origin_server_ts = ? WHERE event_id = ?"
+
+            for index in range(0, len(rows_to_update), INSERT_CLUMP_SIZE):
+                clump = rows_to_update[index : index + INSERT_CLUMP_SIZE]
+                txn.executemany(sql, clump)
+
+            progress = {
+                "target_min_stream_id_inclusive": target_min_stream_id,
+                "max_stream_id_exclusive": min_stream_id,
+                "rows_inserted": rows_inserted + len(rows_to_update),
+            }
+
+            self._background_update_progress_txn(
+                txn, self.EVENT_ORIGIN_SERVER_TS_NAME, progress
+            )
+
+            return len(rows_to_update)
+
+        result = yield self.runInteraction(
+            self.EVENT_ORIGIN_SERVER_TS_NAME, reindex_search_txn
+        )
+
+        if not result:
+            yield self._end_background_update(self.EVENT_ORIGIN_SERVER_TS_NAME)
+
+        defer.returnValue(result)
+
+    @defer.inlineCallbacks
+    def _cleanup_extremities_bg_update(self, progress, batch_size):
+        """Background update to clean out extremities that should have been
+        deleted previously.
+
+        Mainly used to deal with the aftermath of #5269.
+        """
+
+        # This works by first copying all existing forward extremities into the
+        # `_extremities_to_check` table at start up, and then checking each
+        # event in that table whether we have any descendants that are not
+        # soft-failed/rejected. If that is the case then we delete that event
+        # from the forward extremities table.
+        #
+        # For efficiency, we do this in batches by recursively pulling out all
+        # descendants of a batch until we find the non soft-failed/rejected
+        # events, i.e. the set of descendants whose chain of prev events back
+        # to the batch of extremities are all soft-failed or rejected.
+        # Typically, we won't find any such events as extremities will rarely
+        # have any descendants, but if they do then we should delete those
+        # extremities.
+
+        def _cleanup_extremities_bg_update_txn(txn):
+            # The set of extremity event IDs that we're checking this round
+            original_set = set()
+
+            # A dict[str, set[str]] of event ID to their prev events.
+            graph = {}
+
+            # The set of descendants of the original set that are not rejected
+            # nor soft-failed. Ancestors of these events should be removed
+            # from the forward extremities table.
+            non_rejected_leaves = set()
+
+            # Set of event IDs that have been soft failed, and for which we
+            # should check if they have descendants which haven't been soft
+            # failed.
+            soft_failed_events_to_lookup = set()
+
+            # First, we get `batch_size` events from the table, pulling out
+            # their successor events, if any, and the successor events'
+            # rejection status.
+            txn.execute(
+                """SELECT prev_event_id, event_id, internal_metadata,
+                    rejections.event_id IS NOT NULL, events.outlier
+                FROM (
+                    SELECT event_id AS prev_event_id
+                    FROM _extremities_to_check
+                    LIMIT ?
+                ) AS f
+                LEFT JOIN event_edges USING (prev_event_id)
+                LEFT JOIN events USING (event_id)
+                LEFT JOIN event_json USING (event_id)
+                LEFT JOIN rejections USING (event_id)
+                """, (batch_size,)
+            )
+
+            for prev_event_id, event_id, metadata, rejected, outlier in txn:
+                original_set.add(prev_event_id)
+
+                if not event_id or outlier:
+                    # Common case where the forward extremity doesn't have any
+                    # descendants.
+                    continue
+
+                graph.setdefault(event_id, set()).add(prev_event_id)
+
+                soft_failed = False
+                if metadata:
+                    soft_failed = json.loads(metadata).get("soft_failed")
+
+                if soft_failed or rejected:
+                    soft_failed_events_to_lookup.add(event_id)
+                else:
+                    non_rejected_leaves.add(event_id)
+
+            # Now we recursively check all the soft-failed descendants we
+            # found above in the same way, until we have nothing left to
+            # check.
+            while soft_failed_events_to_lookup:
+                # We only want to do 100 at a time, so we split given list
+                # into two.
+                batch = list(soft_failed_events_to_lookup)
+                to_check, to_defer = batch[:100], batch[100:]
+                soft_failed_events_to_lookup = set(to_defer)
+
+                sql = """SELECT prev_event_id, event_id, internal_metadata,
+                    rejections.event_id IS NOT NULL
+                    FROM event_edges
+                    INNER JOIN events USING (event_id)
+                    INNER JOIN event_json USING (event_id)
+                    LEFT JOIN rejections USING (event_id)
+                    WHERE
+                        prev_event_id IN (%s)
+                        AND NOT events.outlier
+                """ % (
+                    ",".join("?" for _ in to_check),
+                )
+                txn.execute(sql, to_check)
+
+                for prev_event_id, event_id, metadata, rejected in txn:
+                    if event_id in graph:
+                        # Already handled this event previously, but we still
+                        # want to record the edge.
+                        graph[event_id].add(prev_event_id)
+                        continue
+
+                    graph[event_id] = {prev_event_id}
+
+                    soft_failed = json.loads(metadata).get("soft_failed")
+                    if soft_failed or rejected:
+                        soft_failed_events_to_lookup.add(event_id)
+                    else:
+                        non_rejected_leaves.add(event_id)
+
+            # We have a set of non-soft-failed descendants, so we recurse up
+            # the graph to find all ancestors and add them to the set of event
+            # IDs that we can delete from forward extremities table.
+            to_delete = set()
+            while non_rejected_leaves:
+                event_id = non_rejected_leaves.pop()
+                prev_event_ids = graph.get(event_id, set())
+                non_rejected_leaves.update(prev_event_ids)
+                to_delete.update(prev_event_ids)
+
+            to_delete.intersection_update(original_set)
+
+            deleted = self._simple_delete_many_txn(
+                txn=txn,
+                table="event_forward_extremities",
+                column="event_id",
+                iterable=to_delete,
+                keyvalues={},
+            )
+
+            logger.info(
+                "Deleted %d forward extremities of %d checked, to clean up #5269",
+                deleted,
+                len(original_set),
+            )
+
+            if deleted:
+                # We now need to invalidate the caches of these rooms
+                rows = self._simple_select_many_txn(
+                    txn,
+                    table="events",
+                    column="event_id",
+                    iterable=to_delete,
+                    keyvalues={},
+                    retcols=("room_id",)
+                )
+                room_ids = set(row["room_id"] for row in rows)
+                for room_id in room_ids:
+                    txn.call_after(
+                        self.get_latest_event_ids_in_room.invalidate,
+                        (room_id,)
+                    )
+
+            self._simple_delete_many_txn(
+                txn=txn,
+                table="_extremities_to_check",
+                column="event_id",
+                iterable=original_set,
+                keyvalues={},
+            )
+
+            return len(original_set)
+
+        num_handled = yield self.runInteraction(
+            "_cleanup_extremities_bg_update", _cleanup_extremities_bg_update_txn,
+        )
+
+        if not num_handled:
+            yield self._end_background_update(self.DELETE_SOFT_FAILED_EXTREMITIES)
+
+            def _drop_table_txn(txn):
+                txn.execute("DROP TABLE _extremities_to_check")
+
+            yield self.runInteraction(
+                "_cleanup_extremities_bg_update_drop_table",
+                _drop_table_txn,
+            )
+
+        defer.returnValue(num_handled)
diff --git a/synapse/storage/events_worker.py b/synapse/storage/events_worker.py
index 663991a9b6..1782428048 100644
--- a/synapse/storage/events_worker.py
+++ b/synapse/storage/events_worker.py
@@ -13,6 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import division
+
 import itertools
 import logging
 from collections import namedtuple
@@ -103,7 +105,7 @@ class EventsWorkerStore(SQLBaseStore):
         Returns:
             Deferred : A FrozenEvent.
         """
-        events = yield self._get_events(
+        events = yield self.get_events_as_list(
             [event_id],
             check_redacted=check_redacted,
             get_prev_content=get_prev_content,
@@ -142,7 +144,7 @@ class EventsWorkerStore(SQLBaseStore):
         Returns:
             Deferred : Dict from event_id to event.
         """
-        events = yield self._get_events(
+        events = yield self.get_events_as_list(
             event_ids,
             check_redacted=check_redacted,
             get_prev_content=get_prev_content,
@@ -152,13 +154,32 @@ class EventsWorkerStore(SQLBaseStore):
         defer.returnValue({e.event_id: e for e in events})
 
     @defer.inlineCallbacks
-    def _get_events(
+    def get_events_as_list(
         self,
         event_ids,
         check_redacted=True,
         get_prev_content=False,
         allow_rejected=False,
     ):
+        """Get events from the database and return in a list in the same order
+        as given by `event_ids` arg.
+
+        Args:
+            event_ids (list): The event_ids of the events to fetch
+            check_redacted (bool): If True, check if event has been redacted
+                and redact it.
+            get_prev_content (bool): If True and event is a state event,
+                include the previous states content in the unsigned field.
+            allow_rejected (bool): If True return rejected events.
+
+        Returns:
+            Deferred[list[EventBase]]: List of events fetched from the database. The
+            events are in the same order as `event_ids` arg.
+
+            Note that the returned list may be smaller than the list of event
+            IDs if not all events could be fetched.
+        """
+
         if not event_ids:
             defer.returnValue([])
 
@@ -202,21 +223,22 @@ class EventsWorkerStore(SQLBaseStore):
                     #
                     # The problem is that we end up at this point when an event
                     # which has been redacted is pulled out of the database by
-                    # _enqueue_events, because _enqueue_events needs to check the
-                    # redaction before it can cache the redacted event. So obviously,
-                    # calling get_event to get the redacted event out of the database
-                    # gives us an infinite loop.
+                    # _enqueue_events, because _enqueue_events needs to check
+                    # the redaction before it can cache the redacted event. So
+                    # obviously, calling get_event to get the redacted event out
+                    # of the database gives us an infinite loop.
                     #
-                    # For now (quick hack to fix during 0.99 release cycle), we just
-                    # go and fetch the relevant row from the db, but it would be nice
-                    # to think about how we can cache this rather than hit the db
-                    # every time we access a redaction event.
+                    # For now (quick hack to fix during 0.99 release cycle), we
+                    # just go and fetch the relevant row from the db, but it
+                    # would be nice to think about how we can cache this rather
+                    # than hit the db every time we access a redaction event.
                     #
                     # One thought on how to do this:
-                    #  1. split _get_events up so that it is divided into (a) get the
-                    #     rawish event from the db/cache, (b) do the redaction/rejection
-                    #     filtering
-                    #  2. have _get_event_from_row just call the first half of that
+                    #  1. split get_events_as_list up so that it is divided into
+                    #     (a) get the rawish event from the db/cache, (b) do the
+                    #     redaction/rejection filtering
+                    #  2. have _get_event_from_row just call the first half of
+                    #     that
 
                     orig_sender = yield self._simple_select_one_onecol(
                         table="events",
@@ -590,4 +612,79 @@ class EventsWorkerStore(SQLBaseStore):
 
             return res
 
-        return self.runInteraction("get_rejection_reasons", f)
+        return self.runInteraction("get_seen_events_with_rejections", f)
+
+    def _get_total_state_event_counts_txn(self, txn, room_id):
+        """
+        See get_total_state_event_counts.
+        """
+        # We join against the events table as that has an index on room_id
+        sql = """
+            SELECT COUNT(*) FROM state_events
+            INNER JOIN events USING (room_id, event_id)
+            WHERE room_id=?
+        """
+        txn.execute(sql, (room_id,))
+        row = txn.fetchone()
+        return row[0] if row else 0
+
+    def get_total_state_event_counts(self, room_id):
+        """
+        Gets the total number of state events in a room.
+
+        Args:
+            room_id (str)
+
+        Returns:
+            Deferred[int]
+        """
+        return self.runInteraction(
+            "get_total_state_event_counts",
+            self._get_total_state_event_counts_txn, room_id
+        )
+
+    def _get_current_state_event_counts_txn(self, txn, room_id):
+        """
+        See get_current_state_event_counts.
+        """
+        sql = "SELECT COUNT(*) FROM current_state_events WHERE room_id=?"
+        txn.execute(sql, (room_id,))
+        row = txn.fetchone()
+        return row[0] if row else 0
+
+    def get_current_state_event_counts(self, room_id):
+        """
+        Gets the current number of state events in a room.
+
+        Args:
+            room_id (str)
+
+        Returns:
+            Deferred[int]
+        """
+        return self.runInteraction(
+            "get_current_state_event_counts",
+            self._get_current_state_event_counts_txn, room_id
+        )
+
+    @defer.inlineCallbacks
+    def get_room_complexity(self, room_id):
+        """
+        Get a rough approximation of the complexity of the room. This is used by
+        remote servers to decide whether they wish to join the room or not.
+        Higher complexity value indicates that being in the room will consume
+        more resources.
+
+        Args:
+            room_id (str)
+
+        Returns:
+            Deferred[dict[str:int]] of complexity version to complexity.
+        """
+        state_events = yield self.get_current_state_event_counts(room_id)
+
+        # Call this one "v1", so we can introduce new ones as we want to develop
+        # it.
+        complexity_v1 = round(state_events / 500, 2)
+
+        defer.returnValue({"v1": complexity_v1})
diff --git a/synapse/storage/keys.py b/synapse/storage/keys.py
index 7036541792..5300720dbb 100644
--- a/synapse/storage/keys.py
+++ b/synapse/storage/keys.py
@@ -19,6 +19,7 @@ import logging
 
 import six
 
+import attr
 from signedjson.key import decode_verify_key_bytes
 
 from synapse.util import batch_iter
@@ -36,6 +37,12 @@ else:
     db_binary_type = memoryview
 
 
+@attr.s(slots=True, frozen=True)
+class FetchKeyResult(object):
+    verify_key = attr.ib()  # VerifyKey: the key itself
+    valid_until_ts = attr.ib()  # int: how long we can use this key for
+
+
 class KeyStore(SQLBaseStore):
     """Persistence for signature verification keys
     """
@@ -54,8 +61,8 @@ class KeyStore(SQLBaseStore):
                 iterable of (server_name, key-id) tuples to fetch keys for
 
         Returns:
-            Deferred: resolves to dict[Tuple[str, str], VerifyKey|None]:
-                map from (server_name, key_id) -> VerifyKey, or None if the key is
+            Deferred: resolves to dict[Tuple[str, str], FetchKeyResult|None]:
+                map from (server_name, key_id) -> FetchKeyResult, or None if the key is
                 unknown
         """
         keys = {}
@@ -65,17 +72,19 @@ class KeyStore(SQLBaseStore):
 
             # batch_iter always returns tuples so it's safe to do len(batch)
             sql = (
-                "SELECT server_name, key_id, verify_key FROM server_signature_keys "
-                "WHERE 1=0"
+                "SELECT server_name, key_id, verify_key, ts_valid_until_ms "
+                "FROM server_signature_keys WHERE 1=0"
             ) + " OR (server_name=? AND key_id=?)" * len(batch)
 
             txn.execute(sql, tuple(itertools.chain.from_iterable(batch)))
 
             for row in txn:
-                server_name, key_id, key_bytes = row
-                keys[(server_name, key_id)] = decode_verify_key_bytes(
-                    key_id, bytes(key_bytes)
+                server_name, key_id, key_bytes, ts_valid_until_ms = row
+                res = FetchKeyResult(
+                    verify_key=decode_verify_key_bytes(key_id, bytes(key_bytes)),
+                    valid_until_ts=ts_valid_until_ms,
                 )
+                keys[(server_name, key_id)] = res
 
         def _txn(txn):
             for batch in batch_iter(server_name_and_key_ids, 50):
@@ -84,38 +93,53 @@ class KeyStore(SQLBaseStore):
 
         return self.runInteraction("get_server_verify_keys", _txn)
 
-    def store_server_verify_key(
-        self, server_name, from_server, time_now_ms, verify_key
-    ):
-        """Stores a NACL verification key for the given server.
+    def store_server_verify_keys(self, from_server, ts_added_ms, verify_keys):
+        """Stores NACL verification keys for remote servers.
         Args:
-            server_name (str): The name of the server.
-            from_server (str): Where the verification key was looked up
-            time_now_ms (int): The time now in milliseconds
-            verify_key (nacl.signing.VerifyKey): The NACL verify key.
+            from_server (str): Where the verification keys were looked up
+            ts_added_ms (int): The time to record that the key was added
+            verify_keys (iterable[tuple[str, str, FetchKeyResult]]):
+                keys to be stored. Each entry is a triplet of
+                (server_name, key_id, key).
         """
-        key_id = "%s:%s" % (verify_key.alg, verify_key.version)
-
-        # XXX fix this to not need a lock (#3819)
-        def _txn(txn):
-            self._simple_upsert_txn(
-                txn,
-                table="server_signature_keys",
-                keyvalues={"server_name": server_name, "key_id": key_id},
-                values={
-                    "from_server": from_server,
-                    "ts_added_ms": time_now_ms,
-                    "verify_key": db_binary_type(verify_key.encode()),
-                },
+        key_values = []
+        value_values = []
+        invalidations = []
+        for server_name, key_id, fetch_result in verify_keys:
+            key_values.append((server_name, key_id))
+            value_values.append(
+                (
+                    from_server,
+                    ts_added_ms,
+                    fetch_result.valid_until_ts,
+                    db_binary_type(fetch_result.verify_key.encode()),
+                )
             )
             # invalidate takes a tuple corresponding to the params of
             # _get_server_verify_key. _get_server_verify_key only takes one
             # param, which is itself the 2-tuple (server_name, key_id).
-            txn.call_after(
-                self._get_server_verify_key.invalidate, ((server_name, key_id),)
-            )
-
-        return self.runInteraction("store_server_verify_key", _txn)
+            invalidations.append((server_name, key_id))
+
+        def _invalidate(res):
+            f = self._get_server_verify_key.invalidate
+            for i in invalidations:
+                f((i, ))
+            return res
+
+        return self.runInteraction(
+            "store_server_verify_keys",
+            self._simple_upsert_many_txn,
+            table="server_signature_keys",
+            key_names=("server_name", "key_id"),
+            key_values=key_values,
+            value_names=(
+                "from_server",
+                "ts_added_ms",
+                "ts_valid_until_ms",
+                "verify_key",
+            ),
+            value_values=value_values,
+        ).addCallback(_invalidate)
 
     def store_server_keys_json(
         self, server_name, key_id, from_server, ts_now_ms, ts_expires_ms, key_json_bytes
diff --git a/synapse/storage/registration.py b/synapse/storage/registration.py
index 03a06a83d6..4cf159ba81 100644
--- a/synapse/storage/registration.py
+++ b/synapse/storage/registration.py
@@ -1,5 +1,7 @@
 # -*- coding: utf-8 -*-
-# Copyright 2014 - 2016 OpenMarket Ltd
+# Copyright 2014-2016 OpenMarket Ltd
+# Copyright 2017-2018 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.
@@ -725,17 +727,7 @@ class RegistrationStore(
             raise StoreError(400, "User ID already taken.", errcode=Codes.USER_IN_USE)
 
         if self._account_validity.enabled:
-            now_ms = self.clock.time_msec()
-            expiration_ts = now_ms + self._account_validity.period
-            self._simple_insert_txn(
-                txn,
-                "account_validity",
-                values={
-                    "user_id": user_id,
-                    "expiration_ts_ms": expiration_ts,
-                    "email_sent": False,
-                }
-            )
+            self.set_expiration_date_for_user_txn(txn, user_id)
 
         if token:
             # it's possible for this to get a conflict, but only for a single user
diff --git a/synapse/storage/relations.py b/synapse/storage/relations.py
new file mode 100644
index 0000000000..4c83800cca
--- /dev/null
+++ b/synapse/storage/relations.py
@@ -0,0 +1,476 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 New Vector Ltd
+#
+# 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.
+
+import logging
+
+import attr
+
+from twisted.internet import defer
+
+from synapse.api.constants import RelationTypes
+from synapse.api.errors import SynapseError
+from synapse.storage._base import SQLBaseStore
+from synapse.storage.stream import generate_pagination_where_clause
+from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
+
+logger = logging.getLogger(__name__)
+
+
+@attr.s
+class PaginationChunk(object):
+    """Returned by relation pagination APIs.
+
+    Attributes:
+        chunk (list): The rows returned by pagination
+        next_batch (Any|None): Token to fetch next set of results with, if
+            None then there are no more results.
+        prev_batch (Any|None): Token to fetch previous set of results with, if
+            None then there are no previous results.
+    """
+
+    chunk = attr.ib()
+    next_batch = attr.ib(default=None)
+    prev_batch = attr.ib(default=None)
+
+    def to_dict(self):
+        d = {"chunk": self.chunk}
+
+        if self.next_batch:
+            d["next_batch"] = self.next_batch.to_string()
+
+        if self.prev_batch:
+            d["prev_batch"] = self.prev_batch.to_string()
+
+        return d
+
+
+@attr.s(frozen=True, slots=True)
+class RelationPaginationToken(object):
+    """Pagination token for relation pagination API.
+
+    As the results are order by topological ordering, we can use the
+    `topological_ordering` and `stream_ordering` fields of the events at the
+    boundaries of the chunk as pagination tokens.
+
+    Attributes:
+        topological (int): The topological ordering of the boundary event
+        stream (int): The stream ordering of the boundary event.
+    """
+
+    topological = attr.ib()
+    stream = attr.ib()
+
+    @staticmethod
+    def from_string(string):
+        try:
+            t, s = string.split("-")
+            return RelationPaginationToken(int(t), int(s))
+        except ValueError:
+            raise SynapseError(400, "Invalid token")
+
+    def to_string(self):
+        return "%d-%d" % (self.topological, self.stream)
+
+    def as_tuple(self):
+        return attr.astuple(self)
+
+
+@attr.s(frozen=True, slots=True)
+class AggregationPaginationToken(object):
+    """Pagination token for relation aggregation pagination API.
+
+    As the results are order by count and then MAX(stream_ordering) of the
+    aggregation groups, we can just use them as our pagination token.
+
+    Attributes:
+        count (int): The count of relations in the boundar group.
+        stream (int): The MAX stream ordering in the boundary group.
+    """
+
+    count = attr.ib()
+    stream = attr.ib()
+
+    @staticmethod
+    def from_string(string):
+        try:
+            c, s = string.split("-")
+            return AggregationPaginationToken(int(c), int(s))
+        except ValueError:
+            raise SynapseError(400, "Invalid token")
+
+    def to_string(self):
+        return "%d-%d" % (self.count, self.stream)
+
+    def as_tuple(self):
+        return attr.astuple(self)
+
+
+class RelationsWorkerStore(SQLBaseStore):
+    @cached(tree=True)
+    def get_relations_for_event(
+        self,
+        event_id,
+        relation_type=None,
+        event_type=None,
+        aggregation_key=None,
+        limit=5,
+        direction="b",
+        from_token=None,
+        to_token=None,
+    ):
+        """Get a list of relations for an event, ordered by topological ordering.
+
+        Args:
+            event_id (str): Fetch events that relate to this event ID.
+            relation_type (str|None): Only fetch events with this relation
+                type, if given.
+            event_type (str|None): Only fetch events with this event type, if
+                given.
+            aggregation_key (str|None): Only fetch events with this aggregation
+                key, if given.
+            limit (int): Only fetch the most recent `limit` events.
+            direction (str): Whether to fetch the most recent first (`"b"`) or
+                the oldest first (`"f"`).
+            from_token (RelationPaginationToken|None): Fetch rows from the given
+                token, or from the start if None.
+            to_token (RelationPaginationToken|None): Fetch rows up to the given
+                token, or up to the end if None.
+
+        Returns:
+            Deferred[PaginationChunk]: List of event IDs that match relations
+            requested. The rows are of the form `{"event_id": "..."}`.
+        """
+
+        where_clause = ["relates_to_id = ?"]
+        where_args = [event_id]
+
+        if relation_type is not None:
+            where_clause.append("relation_type = ?")
+            where_args.append(relation_type)
+
+        if event_type is not None:
+            where_clause.append("type = ?")
+            where_args.append(event_type)
+
+        if aggregation_key:
+            where_clause.append("aggregation_key = ?")
+            where_args.append(aggregation_key)
+
+        pagination_clause = generate_pagination_where_clause(
+            direction=direction,
+            column_names=("topological_ordering", "stream_ordering"),
+            from_token=attr.astuple(from_token) if from_token else None,
+            to_token=attr.astuple(to_token) if to_token else None,
+            engine=self.database_engine,
+        )
+
+        if pagination_clause:
+            where_clause.append(pagination_clause)
+
+        if direction == "b":
+            order = "DESC"
+        else:
+            order = "ASC"
+
+        sql = """
+            SELECT event_id, topological_ordering, stream_ordering
+            FROM event_relations
+            INNER JOIN events USING (event_id)
+            WHERE %s
+            ORDER BY topological_ordering %s, stream_ordering %s
+            LIMIT ?
+        """ % (
+            " AND ".join(where_clause),
+            order,
+            order,
+        )
+
+        def _get_recent_references_for_event_txn(txn):
+            txn.execute(sql, where_args + [limit + 1])
+
+            last_topo_id = None
+            last_stream_id = None
+            events = []
+            for row in txn:
+                events.append({"event_id": row[0]})
+                last_topo_id = row[1]
+                last_stream_id = row[2]
+
+            next_batch = None
+            if len(events) > limit and last_topo_id and last_stream_id:
+                next_batch = RelationPaginationToken(last_topo_id, last_stream_id)
+
+            return PaginationChunk(
+                chunk=list(events[:limit]), next_batch=next_batch, prev_batch=from_token
+            )
+
+        return self.runInteraction(
+            "get_recent_references_for_event", _get_recent_references_for_event_txn
+        )
+
+    @cached(tree=True)
+    def get_aggregation_groups_for_event(
+        self,
+        event_id,
+        event_type=None,
+        limit=5,
+        direction="b",
+        from_token=None,
+        to_token=None,
+    ):
+        """Get a list of annotations on the event, grouped by event type and
+        aggregation key, sorted by count.
+
+        This is used e.g. to get the what and how many reactions have happend
+        on an event.
+
+        Args:
+            event_id (str): Fetch events that relate to this event ID.
+            event_type (str|None): Only fetch events with this event type, if
+                given.
+            limit (int): Only fetch the `limit` groups.
+            direction (str): Whether to fetch the highest count first (`"b"`) or
+                the lowest count first (`"f"`).
+            from_token (AggregationPaginationToken|None): Fetch rows from the
+                given token, or from the start if None.
+            to_token (AggregationPaginationToken|None): Fetch rows up to the
+                given token, or up to the end if None.
+
+
+        Returns:
+            Deferred[PaginationChunk]: List of groups of annotations that
+            match. Each row is a dict with `type`, `key` and `count` fields.
+        """
+
+        where_clause = ["relates_to_id = ?", "relation_type = ?"]
+        where_args = [event_id, RelationTypes.ANNOTATION]
+
+        if event_type:
+            where_clause.append("type = ?")
+            where_args.append(event_type)
+
+        having_clause = generate_pagination_where_clause(
+            direction=direction,
+            column_names=("COUNT(*)", "MAX(stream_ordering)"),
+            from_token=attr.astuple(from_token) if from_token else None,
+            to_token=attr.astuple(to_token) if to_token else None,
+            engine=self.database_engine,
+        )
+
+        if direction == "b":
+            order = "DESC"
+        else:
+            order = "ASC"
+
+        if having_clause:
+            having_clause = "HAVING " + having_clause
+        else:
+            having_clause = ""
+
+        sql = """
+            SELECT type, aggregation_key, COUNT(DISTINCT sender), MAX(stream_ordering)
+            FROM event_relations
+            INNER JOIN events USING (event_id)
+            WHERE {where_clause}
+            GROUP BY relation_type, type, aggregation_key
+            {having_clause}
+            ORDER BY COUNT(*) {order}, MAX(stream_ordering) {order}
+            LIMIT ?
+        """.format(
+            where_clause=" AND ".join(where_clause),
+            order=order,
+            having_clause=having_clause,
+        )
+
+        def _get_aggregation_groups_for_event_txn(txn):
+            txn.execute(sql, where_args + [limit + 1])
+
+            next_batch = None
+            events = []
+            for row in txn:
+                events.append({"type": row[0], "key": row[1], "count": row[2]})
+                next_batch = AggregationPaginationToken(row[2], row[3])
+
+            if len(events) <= limit:
+                next_batch = None
+
+            return PaginationChunk(
+                chunk=list(events[:limit]), next_batch=next_batch, prev_batch=from_token
+            )
+
+        return self.runInteraction(
+            "get_aggregation_groups_for_event", _get_aggregation_groups_for_event_txn
+        )
+
+    @cachedInlineCallbacks()
+    def get_applicable_edit(self, event_id):
+        """Get the most recent edit (if any) that has happened for the given
+        event.
+
+        Correctly handles checking whether edits were allowed to happen.
+
+        Args:
+            event_id (str): The original event ID
+
+        Returns:
+            Deferred[EventBase|None]: Returns the most recent edit, if any.
+        """
+
+        # We only allow edits for `m.room.message` events that have the same sender
+        # and event type. We can't assert these things during regular event auth so
+        # we have to do the checks post hoc.
+
+        # Fetches latest edit that has the same type and sender as the
+        # original, and is an `m.room.message`.
+        sql = """
+            SELECT edit.event_id FROM events AS edit
+            INNER JOIN event_relations USING (event_id)
+            INNER JOIN events AS original ON
+                original.event_id = relates_to_id
+                AND edit.type = original.type
+                AND edit.sender = original.sender
+            WHERE
+                relates_to_id = ?
+                AND relation_type = ?
+                AND edit.type = 'm.room.message'
+            ORDER by edit.origin_server_ts DESC, edit.event_id DESC
+            LIMIT 1
+        """
+
+        def _get_applicable_edit_txn(txn):
+            txn.execute(sql, (event_id, RelationTypes.REPLACE))
+            row = txn.fetchone()
+            if row:
+                return row[0]
+
+        edit_id = yield self.runInteraction(
+            "get_applicable_edit", _get_applicable_edit_txn
+        )
+
+        if not edit_id:
+            return
+
+        edit_event = yield self.get_event(edit_id, allow_none=True)
+        defer.returnValue(edit_event)
+
+    def has_user_annotated_event(self, parent_id, event_type, aggregation_key, sender):
+        """Check if a user has already annotated an event with the same key
+        (e.g. already liked an event).
+
+        Args:
+            parent_id (str): The event being annotated
+            event_type (str): The event type of the annotation
+            aggregation_key (str): The aggregation key of the annotation
+            sender (str): The sender of the annotation
+
+        Returns:
+            Deferred[bool]
+        """
+
+        sql = """
+            SELECT 1 FROM event_relations
+            INNER JOIN events USING (event_id)
+            WHERE
+                relates_to_id = ?
+                AND relation_type = ?
+                AND type = ?
+                AND sender = ?
+                AND aggregation_key = ?
+            LIMIT 1;
+        """
+
+        def _get_if_user_has_annotated_event(txn):
+            txn.execute(
+                sql,
+                (
+                    parent_id,
+                    RelationTypes.ANNOTATION,
+                    event_type,
+                    sender,
+                    aggregation_key,
+                ),
+            )
+
+            return bool(txn.fetchone())
+
+        return self.runInteraction(
+            "get_if_user_has_annotated_event", _get_if_user_has_annotated_event
+        )
+
+
+class RelationsStore(RelationsWorkerStore):
+    def _handle_event_relations(self, txn, event):
+        """Handles inserting relation data during peristence of events
+
+        Args:
+            txn
+            event (EventBase)
+        """
+        relation = event.content.get("m.relates_to")
+        if not relation:
+            # No relations
+            return
+
+        rel_type = relation.get("rel_type")
+        if rel_type not in (
+            RelationTypes.ANNOTATION,
+            RelationTypes.REFERENCE,
+            RelationTypes.REPLACE,
+        ):
+            # Unknown relation type
+            return
+
+        parent_id = relation.get("event_id")
+        if not parent_id:
+            # Invalid relation
+            return
+
+        aggregation_key = relation.get("key")
+
+        self._simple_insert_txn(
+            txn,
+            table="event_relations",
+            values={
+                "event_id": event.event_id,
+                "relates_to_id": parent_id,
+                "relation_type": rel_type,
+                "aggregation_key": aggregation_key,
+            },
+        )
+
+        txn.call_after(self.get_relations_for_event.invalidate_many, (parent_id,))
+        txn.call_after(
+            self.get_aggregation_groups_for_event.invalidate_many, (parent_id,)
+        )
+
+        if rel_type == RelationTypes.REPLACE:
+            txn.call_after(self.get_applicable_edit.invalidate, (parent_id,))
+
+    def _handle_redaction(self, txn, redacted_event_id):
+        """Handles receiving a redaction and checking whether we need to remove
+        any redacted relations from the database.
+
+        Args:
+            txn
+            redacted_event_id (str): The event that was redacted.
+        """
+
+        self._simple_delete_txn(
+            txn,
+            table="event_relations",
+            keyvalues={
+                "event_id": redacted_event_id,
+            }
+        )
diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index 57df17bcc2..7617913326 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -142,6 +142,27 @@ class RoomMemberWorkerStore(EventsWorkerStore):
 
         return self.runInteraction("get_room_summary", _get_room_summary_txn)
 
+    def _get_user_counts_in_room_txn(self, txn, room_id):
+        """
+        Get the user count in a room by membership.
+
+        Args:
+            room_id (str)
+            membership (Membership)
+
+        Returns:
+            Deferred[int]
+        """
+        sql = """
+        SELECT m.membership, count(*) FROM room_memberships as m
+            INNER JOIN current_state_events as c USING(event_id)
+            WHERE c.type = 'm.room.member' AND c.room_id = ?
+            GROUP BY m.membership
+        """
+
+        txn.execute(sql, (room_id,))
+        return {row[0]: row[1] for row in txn}
+
     @cached()
     def get_invited_rooms_for_user(self, user_id):
         """ Get all the rooms the user is invited to
diff --git a/synapse/storage/schema/delta/54/account_validity.sql b/synapse/storage/schema/delta/54/account_validity_with_renewal.sql
index 2357626000..0adb2ad55e 100644
--- a/synapse/storage/schema/delta/54/account_validity.sql
+++ b/synapse/storage/schema/delta/54/account_validity_with_renewal.sql
@@ -13,6 +13,9 @@
  * limitations under the License.
  */
 
+-- We previously changed the schema for this table without renaming the file, which means
+-- that some databases might still be using the old schema. This ensures Synapse uses the
+-- right schema for the table.
 DROP TABLE IF EXISTS account_validity;
 
 -- Track what users are in public rooms.
diff --git a/synapse/storage/schema/delta/54/add_validity_to_server_keys.sql b/synapse/storage/schema/delta/54/add_validity_to_server_keys.sql
new file mode 100644
index 0000000000..c01aa9d2d9
--- /dev/null
+++ b/synapse/storage/schema/delta/54/add_validity_to_server_keys.sql
@@ -0,0 +1,23 @@
+/* Copyright 2019 New Vector Ltd
+ *
+ * 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.
+ */
+
+/* When we can use this key until, before we have to refresh it. */
+ALTER TABLE server_signature_keys ADD COLUMN ts_valid_until_ms BIGINT;
+
+UPDATE server_signature_keys SET ts_valid_until_ms = (
+    SELECT MAX(ts_valid_until_ms) FROM server_keys_json skj WHERE
+        skj.server_name = server_signature_keys.server_name AND
+        skj.key_id = server_signature_keys.key_id
+);
diff --git a/synapse/storage/schema/delta/54/delete_forward_extremities.sql b/synapse/storage/schema/delta/54/delete_forward_extremities.sql
new file mode 100644
index 0000000000..b062ec840c
--- /dev/null
+++ b/synapse/storage/schema/delta/54/delete_forward_extremities.sql
@@ -0,0 +1,23 @@
+/* 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.
+ */
+
+-- Start a background job to cleanup extremities that were incorrectly added
+-- by bug #5269.
+INSERT INTO background_updates (update_name, progress_json) VALUES
+  ('delete_soft_failed_extremities', '{}');
+
+DROP TABLE IF EXISTS _extremities_to_check;  -- To make this delta schema file idempotent.
+CREATE TABLE _extremities_to_check AS SELECT event_id FROM event_forward_extremities;
+CREATE INDEX _extremities_to_check_id ON _extremities_to_check(event_id);
diff --git a/synapse/storage/schema/delta/54/relations.sql b/synapse/storage/schema/delta/54/relations.sql
new file mode 100644
index 0000000000..134862b870
--- /dev/null
+++ b/synapse/storage/schema/delta/54/relations.sql
@@ -0,0 +1,27 @@
+/* Copyright 2019 New Vector Ltd
+ *
+ * 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.
+ */
+
+-- Tracks related events, like reactions, replies, edits, etc. Note that things
+-- in this table are not necessarily "valid", e.g. it may contain edits from
+-- people who don't have power to edit other peoples events.
+CREATE TABLE IF NOT EXISTS event_relations (
+    event_id TEXT NOT NULL,
+    relates_to_id TEXT NOT NULL,
+    relation_type TEXT NOT NULL,
+    aggregation_key TEXT
+);
+
+CREATE UNIQUE INDEX event_relations_id ON event_relations(event_id);
+CREATE INDEX event_relations_relates ON event_relations(relates_to_id, relation_type, aggregation_key);
diff --git a/synapse/storage/schema/delta/54/stats.sql b/synapse/storage/schema/delta/54/stats.sql
new file mode 100644
index 0000000000..652e58308e
--- /dev/null
+++ b/synapse/storage/schema/delta/54/stats.sql
@@ -0,0 +1,80 @@
+/* Copyright 2018 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+CREATE TABLE stats_stream_pos (
+    Lock CHAR(1) NOT NULL DEFAULT 'X' UNIQUE,  -- Makes sure this table only has one row.
+    stream_id BIGINT,
+    CHECK (Lock='X')
+);
+
+INSERT INTO stats_stream_pos (stream_id) VALUES (null);
+
+CREATE TABLE user_stats (
+    user_id TEXT NOT NULL,
+    ts BIGINT NOT NULL,
+    bucket_size INT NOT NULL,
+    public_rooms INT NOT NULL,
+    private_rooms INT NOT NULL
+);
+
+CREATE UNIQUE INDEX user_stats_user_ts ON user_stats(user_id, ts);
+
+CREATE TABLE room_stats (
+    room_id TEXT NOT NULL,
+    ts BIGINT NOT NULL,
+    bucket_size INT NOT NULL,
+    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,
+    state_events INT NOT NULL
+);
+
+CREATE UNIQUE INDEX room_stats_room_ts ON room_stats(room_id, ts);
+
+-- cache of current room state; useful for the publicRooms list
+CREATE TABLE room_state (
+    room_id TEXT NOT NULL,
+    join_rules TEXT,
+    history_visibility TEXT,
+    encryption TEXT,
+    name TEXT,
+    topic TEXT,
+    avatar TEXT,
+    canonical_alias TEXT
+    -- get aliases straight from the right table
+);
+
+CREATE UNIQUE INDEX room_state_room ON room_state(room_id);
+
+CREATE TABLE room_stats_earliest_token (
+    room_id TEXT NOT NULL,
+    token BIGINT NOT NULL
+);
+
+CREATE UNIQUE INDEX room_stats_earliest_token_idx ON room_stats_earliest_token(room_id);
+
+-- Set up staging tables
+INSERT INTO background_updates (update_name, progress_json) VALUES
+    ('populate_stats_createtables', '{}');
+
+-- Run through each room and update stats
+INSERT INTO background_updates (update_name, progress_json, depends_on) VALUES
+    ('populate_stats_process_rooms', '{}', 'populate_stats_createtables');
+
+-- Clean up staging tables
+INSERT INTO background_updates (update_name, progress_json, depends_on) VALUES
+    ('populate_stats_cleanup', '{}', 'populate_stats_process_rooms');
diff --git a/synapse/storage/schema/delta/54/stats2.sql b/synapse/storage/schema/delta/54/stats2.sql
new file mode 100644
index 0000000000..3b2d48447f
--- /dev/null
+++ b/synapse/storage/schema/delta/54/stats2.sql
@@ -0,0 +1,28 @@
+/* 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.
+ */
+
+-- This delta file gets run after `54/stats.sql` delta.
+
+-- We want to add some indices to the temporary stats table, so we re-insert
+-- 'populate_stats_createtables' if we are still processing the rooms update.
+INSERT INTO background_updates (update_name, progress_json)
+    SELECT 'populate_stats_createtables', '{}'
+    WHERE
+        'populate_stats_process_rooms' IN (
+            SELECT update_name FROM background_updates
+        )
+        AND 'populate_stats_createtables' NOT IN (  -- don't insert if already exists
+            SELECT update_name FROM background_updates
+        );
diff --git a/synapse/storage/search.py b/synapse/storage/search.py
index 226f8f1b7e..ff49eaae02 100644
--- a/synapse/storage/search.py
+++ b/synapse/storage/search.py
@@ -460,7 +460,7 @@ class SearchStore(BackgroundUpdateStore):
 
         results = list(filter(lambda row: row["room_id"] in room_ids, results))
 
-        events = yield self._get_events([r["event_id"] for r in results])
+        events = yield self.get_events_as_list([r["event_id"] for r in results])
 
         event_map = {ev.event_id: ev for ev in events}
 
@@ -605,7 +605,7 @@ class SearchStore(BackgroundUpdateStore):
 
         results = list(filter(lambda row: row["room_id"] in room_ids, results))
 
-        events = yield self._get_events([r["event_id"] for r in results])
+        events = yield self.get_events_as_list([r["event_id"] for r in results])
 
         event_map = {ev.event_id: ev for ev in events}
 
diff --git a/synapse/storage/state_deltas.py b/synapse/storage/state_deltas.py
index 56e42f583d..5fdb442104 100644
--- a/synapse/storage/state_deltas.py
+++ b/synapse/storage/state_deltas.py
@@ -22,6 +22,24 @@ logger = logging.getLogger(__name__)
 
 class StateDeltasStore(SQLBaseStore):
     def get_current_state_deltas(self, prev_stream_id):
+        """Fetch a list of room state changes since the given stream id
+
+        Each entry in the result contains the following fields:
+            - stream_id (int)
+            - room_id (str)
+            - type (str): event type
+            - state_key (str):
+            - event_id (str|None): new event_id for this state key. None if the
+                state has been deleted.
+            - prev_event_id (str|None): previous event_id for this state key. None
+                if it's new state.
+
+        Args:
+            prev_stream_id (int): point to get changes since (exclusive)
+
+        Returns:
+            Deferred[list[dict]]: results
+        """
         prev_stream_id = int(prev_stream_id)
         if not self._curr_state_delta_stream_cache.has_any_entity_changed(
             prev_stream_id
@@ -66,10 +84,16 @@ class StateDeltasStore(SQLBaseStore):
             "get_current_state_deltas", get_current_state_deltas_txn
         )
 
-    def get_max_stream_id_in_current_state_deltas(self):
-        return self._simple_select_one_onecol(
+    def _get_max_stream_id_in_current_state_deltas_txn(self, txn):
+        return self._simple_select_one_onecol_txn(
+            txn,
             table="current_state_delta_stream",
             keyvalues={},
             retcol="COALESCE(MAX(stream_id), -1)",
-            desc="get_max_stream_id_in_current_state_deltas",
+        )
+
+    def get_max_stream_id_in_current_state_deltas(self):
+        return self.runInteraction(
+            "get_max_stream_id_in_current_state_deltas",
+            self._get_max_stream_id_in_current_state_deltas_txn,
         )
diff --git a/synapse/storage/stats.py b/synapse/storage/stats.py
new file mode 100644
index 0000000000..ff266b09b0
--- /dev/null
+++ b/synapse/storage/stats.py
@@ -0,0 +1,468 @@
+# -*- coding: utf-8 -*-
+# Copyright 2018, 2019 New Vector Ltd
+#
+# 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.
+
+import logging
+
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes, Membership
+from synapse.storage.prepare_database import get_statements
+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)
+ABSOLUTE_STATS_FIELDS = {
+    "room": (
+        "current_state_events",
+        "joined_members",
+        "invited_members",
+        "left_members",
+        "banned_members",
+        "state_events",
+    ),
+    "user": ("public_rooms", "private_rooms"),
+}
+
+TYPE_TO_ROOM = {"room": ("room_stats", "room_id"), "user": ("user_stats", "user_id")}
+
+TEMP_TABLE = "_temp_populate_stats"
+
+
+class StatsStore(StateDeltasStore):
+    def __init__(self, db_conn, hs):
+        super(StatsStore, self).__init__(db_conn, hs)
+
+        self.server_name = hs.hostname
+        self.clock = self.hs.get_clock()
+        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.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
+        )
+
+    @defer.inlineCallbacks
+    def _populate_stats_createtables(self, progress, batch_size):
+
+        if not self.stats_enabled:
+            yield self._end_background_update("populate_stats_createtables")
+            defer.returnValue(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)
+
+        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()
+
+        yield self._end_background_update("populate_stats_createtables")
+        defer.returnValue(1)
+
+    @defer.inlineCallbacks
+    def _populate_stats_cleanup(self, progress, batch_size):
+        """
+        Update the user directory stream position, then clean up the old tables.
+        """
+        if not self.stats_enabled:
+            yield self._end_background_update("populate_stats_cleanup")
+            defer.returnValue(1)
+
+        position = yield self._simple_select_one_onecol(
+            TEMP_TABLE + "_position", None, "position"
+        )
+        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")
+
+        yield self.runInteraction("populate_stats_cleanup", _delete_staging_area)
+
+        yield self._end_background_update("populate_stats_cleanup")
+        defer.returnValue(1)
+
+    @defer.inlineCallbacks
+    def _populate_stats_process_rooms(self, progress, batch_size):
+
+        if not self.stats_enabled:
+            yield self._end_background_update("populate_stats_process_rooms")
+            defer.returnValue(1)
+
+        # If we don't have progress filed, delete everything.
+        if not progress:
+            yield self.delete_all_stats()
+
+        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
+
+        rooms_to_work_on = yield self.runInteraction(
+            "populate_stats_temp_read", _get_next_batch
+        )
+
+        # No more rooms -- complete the transaction.
+        if not rooms_to_work_on:
+            yield self._end_background_update("populate_stats_process_rooms")
+            defer.returnValue(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, ""))
+
+            state_events = yield self.get_events([
+                join_rules_id, history_visibility_id, encryption_id, name_id,
+                topic_id, avatar_id, canonical_alias_id,
+            ])
+
+            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},
+                )
+
+            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.
+                defer.returnValue(processed_event_count)
+
+        defer.returnValue(processed_event_count)
+
+    def delete_all_stats(self):
+        """
+        Delete all statistics records.
+        """
+
+        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",
+            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",
+        )
+
+    def update_room_state(self, room_id, fields):
+        """
+        Args:
+            room_id (str)
+            fields (dict[str:Any])
+        """
+
+        # For whatever reason some of the fields may contain null bytes, which
+        # postgres isn't a fan of, so we replace those fields with null.
+        for col in (
+            "join_rules",
+            "history_visibility",
+            "encryption",
+            "name",
+            "topic",
+            "avatar",
+            "canonical_alias"
+        ):
+            field = fields.get(col)
+            if field and "\0" in field:
+                fields[col] = None
+
+        return self._simple_upsert(
+            table="room_state",
+            keyvalues={"room_id": room_id},
+            values=fields,
+            desc="update_room_state",
+        )
+
+    def get_deltas_for_room(self, room_id, start, size=100):
+        """
+        Get statistics deltas for a given room.
+
+        Args:
+            room_id (str)
+            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".
+        """
+        return self._simple_select_list_paginate(
+            "room_stats",
+            {"room_id": room_id},
+            "ts",
+            start,
+            size,
+            retcols=(list(ABSOLUTE_STATS_FIELDS["room"]) + ["ts"]),
+            order_direction="DESC",
+        )
+
+    def get_all_room_state(self):
+        return self._simple_select_list(
+            "room_state", None, retcols=("name", "topic", "canonical_alias")
+        )
+
+    @cached()
+    def get_earliest_token_for_room_stats(self, room_id):
+        """
+        Fetch the "earliest token". This is used by the room stats delta
+        processor to ignore deltas that have been processed between the
+        start of the background task and any particular room's stats
+        being calculated.
+
+        Returns:
+            Deferred[int]
+        """
+        return self._simple_select_one_onecol(
+            "room_stats_earliest_token",
+            {"room_id": room_id},
+            retcol="token",
+            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 _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, 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},
+                )
+            else:
+                sql = ("UPDATE %s SET %s=%s+? WHERE %s=? AND ts=?") % (
+                    table,
+                    field,
+                    field,
+                    id_col,
+                )
+                txn.execute(sql, (value, stats_id, current_ts))
+
+        return self.runInteraction("update_stats_delta", _update_stats_delta)
diff --git a/synapse/storage/stream.py b/synapse/storage/stream.py
index 9cd1e0f9fe..529ad4ea79 100644
--- a/synapse/storage/stream.py
+++ b/synapse/storage/stream.py
@@ -64,59 +64,135 @@ _EventDictReturn = namedtuple(
 )
 
 
-def lower_bound(token, engine, inclusive=False):
-    inclusive = "=" if inclusive else ""
-    if token.topological is None:
-        return "(%d <%s %s)" % (token.stream, inclusive, "stream_ordering")
-    else:
-        if isinstance(engine, PostgresEngine):
-            # Postgres doesn't optimise ``(x < a) OR (x=a AND y<b)`` as well
-            # as it optimises ``(x,y) < (a,b)`` on multicolumn indexes. So we
-            # use the later form when running against postgres.
-            return "((%d,%d) <%s (%s,%s))" % (
-                token.topological,
-                token.stream,
-                inclusive,
-                "topological_ordering",
-                "stream_ordering",
+def generate_pagination_where_clause(
+    direction, column_names, from_token, to_token, engine,
+):
+    """Creates an SQL expression to bound the columns by the pagination
+    tokens.
+
+    For example creates an SQL expression like:
+
+        (6, 7) >= (topological_ordering, stream_ordering)
+        AND (5, 3) < (topological_ordering, stream_ordering)
+
+    would be generated for dir=b, from_token=(6, 7) and to_token=(5, 3).
+
+    Note that tokens are considered to be after the row they are in, e.g. if
+    a row A has a token T, then we consider A to be before T. This convention
+    is important when figuring out inequalities for the generated SQL, and
+    produces the following result:
+        - If paginating forwards then we exclude any rows matching the from
+          token, but include those that match the to token.
+        - If paginating backwards then we include any rows matching the from
+          token, but include those that match the to token.
+
+    Args:
+        direction (str): Whether we're paginating backwards("b") or
+            forwards ("f").
+        column_names (tuple[str, str]): The column names to bound. Must *not*
+            be user defined as these get inserted directly into the SQL
+            statement without escapes.
+        from_token (tuple[int, int]|None): The start point for the pagination.
+            This is an exclusive minimum bound if direction is "f", and an
+            inclusive maximum bound if direction is "b".
+        to_token (tuple[int, int]|None): The endpoint point for the pagination.
+            This is an inclusive maximum bound if direction is "f", and an
+            exclusive minimum bound if direction is "b".
+        engine: The database engine to generate the clauses for
+
+    Returns:
+        str: The sql expression
+    """
+    assert direction in ("b", "f")
+
+    where_clause = []
+    if from_token:
+        where_clause.append(
+            _make_generic_sql_bound(
+                bound=">=" if direction == "b" else "<",
+                column_names=column_names,
+                values=from_token,
+                engine=engine,
             )
-        return "(%d < %s OR (%d = %s AND %d <%s %s))" % (
-            token.topological,
-            "topological_ordering",
-            token.topological,
-            "topological_ordering",
-            token.stream,
-            inclusive,
-            "stream_ordering",
-        )
-
-
-def upper_bound(token, engine, inclusive=True):
-    inclusive = "=" if inclusive else ""
-    if token.topological is None:
-        return "(%d >%s %s)" % (token.stream, inclusive, "stream_ordering")
-    else:
-        if isinstance(engine, PostgresEngine):
-            # Postgres doesn't optimise ``(x > a) OR (x=a AND y>b)`` as well
-            # as it optimises ``(x,y) > (a,b)`` on multicolumn indexes. So we
-            # use the later form when running against postgres.
-            return "((%d,%d) >%s (%s,%s))" % (
-                token.topological,
-                token.stream,
-                inclusive,
-                "topological_ordering",
-                "stream_ordering",
+        )
+
+    if to_token:
+        where_clause.append(
+            _make_generic_sql_bound(
+                bound="<" if direction == "b" else ">=",
+                column_names=column_names,
+                values=to_token,
+                engine=engine,
             )
-        return "(%d > %s OR (%d = %s AND %d >%s %s))" % (
-            token.topological,
-            "topological_ordering",
-            token.topological,
-            "topological_ordering",
-            token.stream,
-            inclusive,
-            "stream_ordering",
         )
 
+    return " AND ".join(where_clause)
+
+
+def _make_generic_sql_bound(bound, column_names, values, engine):
+    """Create an SQL expression that bounds the given column names by the
+    values, e.g. create the equivalent of `(1, 2) < (col1, col2)`.
+
+    Only works with two columns.
+
+    Older versions of SQLite don't support that syntax so we have to expand it
+    out manually.
+
+    Args:
+        bound (str): The comparison operator to use. One of ">", "<", ">=",
+            "<=", where the values are on the left and columns on the right.
+        names (tuple[str, str]): The column names. Must *not* be user defined
+            as these get inserted directly into the SQL statement without
+            escapes.
+        values (tuple[int|None, int]): The values to bound the columns by. If
+            the first value is None then only creates a bound on the second
+            column.
+        engine: The database engine to generate the SQL for
+
+    Returns:
+        str
+    """
+
+    assert(bound in (">", "<", ">=", "<="))
+
+    name1, name2 = column_names
+    val1, val2 = values
+
+    if val1 is None:
+        val2 = int(val2)
+        return "(%d %s %s)" % (val2, bound, name2)
+
+    val1 = int(val1)
+    val2 = int(val2)
+
+    if isinstance(engine, PostgresEngine):
+        # Postgres doesn't optimise ``(x < a) OR (x=a AND y<b)`` as well
+        # as it optimises ``(x,y) < (a,b)`` on multicolumn indexes. So we
+        # use the later form when running against postgres.
+        return "((%d,%d) %s (%s,%s))" % (
+            val1, val2,
+            bound,
+            name1, name2,
+        )
+
+    # We want to generate queries of e.g. the form:
+    #
+    #   (val1 < name1 OR (val1 = name1 AND val2 <= name2))
+    #
+    # which is equivalent to (val1, val2) < (name1, name2)
+
+    return """(
+        {val1:d} {strict_bound} {name1}
+        OR ({val1:d} = {name1} AND {val2:d} {bound} {name2})
+    )""".format(
+        name1=name1,
+        val1=val1,
+        name2=name2,
+        val2=val2,
+        strict_bound=bound[0],  # The first bound must always be strict equality here
+        bound=bound,
+    )
+
 
 def filter_to_clause(event_filter):
     # NB: This may create SQL clauses that don't optimise well (and we don't
@@ -319,7 +395,9 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
 
         rows = yield self.runInteraction("get_room_events_stream_for_room", f)
 
-        ret = yield self._get_events([r.event_id for r in rows], get_prev_content=True)
+        ret = yield self.get_events_as_list([
+            r.event_id for r in rows], get_prev_content=True,
+        )
 
         self._set_before_and_after(ret, rows, topo_order=from_id is None)
 
@@ -367,7 +445,9 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
 
         rows = yield self.runInteraction("get_membership_changes_for_user", f)
 
-        ret = yield self._get_events([r.event_id for r in rows], get_prev_content=True)
+        ret = yield self.get_events_as_list(
+            [r.event_id for r in rows], get_prev_content=True,
+        )
 
         self._set_before_and_after(ret, rows, topo_order=False)
 
@@ -394,7 +474,7 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
         )
 
         logger.debug("stream before")
-        events = yield self._get_events(
+        events = yield self.get_events_as_list(
             [r.event_id for r in rows], get_prev_content=True
         )
         logger.debug("stream after")
@@ -580,11 +660,11 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
             event_filter,
         )
 
-        events_before = yield self._get_events(
+        events_before = yield self.get_events_as_list(
             [e for e in results["before"]["event_ids"]], get_prev_content=True
         )
 
-        events_after = yield self._get_events(
+        events_after = yield self.get_events_as_list(
             [e for e in results["after"]["event_ids"]], get_prev_content=True
         )
 
@@ -697,7 +777,7 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
             "get_all_new_events_stream", get_all_new_events_stream_txn
         )
 
-        events = yield self._get_events(event_ids)
+        events = yield self.get_events_as_list(event_ids)
 
         defer.returnValue((upper_bound, events))
 
@@ -758,20 +838,16 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
         args = [False, room_id]
         if direction == 'b':
             order = "DESC"
-            bounds = upper_bound(from_token, self.database_engine)
-            if to_token:
-                bounds = "%s AND %s" % (
-                    bounds,
-                    lower_bound(to_token, self.database_engine),
-                )
         else:
             order = "ASC"
-            bounds = lower_bound(from_token, self.database_engine)
-            if to_token:
-                bounds = "%s AND %s" % (
-                    bounds,
-                    upper_bound(to_token, self.database_engine),
-                )
+
+        bounds = generate_pagination_where_clause(
+            direction=direction,
+            column_names=("topological_ordering", "stream_ordering"),
+            from_token=from_token,
+            to_token=to_token,
+            engine=self.database_engine,
+        )
 
         filter_clause, filter_args = filter_to_clause(event_filter)
 
@@ -849,7 +925,7 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
             event_filter,
         )
 
-        events = yield self._get_events(
+        events = yield self.get_events_as_list(
             [r.event_id for r in rows], get_prev_content=True
         )