Merge branch 'release-v0.18.0' of github.com:matrix-org/synapse v0.18.0

26 files changed, 1246 insertions, 140 deletions

diff --git a/synapse/storage/__init__.py b/synapse/storage/__init__.py
index 6c32773f25..9996f195a0 100644
--- a/synapse/storage/__init__.py
+++ b/synapse/storage/__init__.py
@@ -111,7 +111,10 @@ class DataStore(RoomMemberStore, RoomStore,
             db_conn, "presence_stream", "stream_id"
         )
         self._device_inbox_id_gen = StreamIdGenerator(
-            db_conn, "device_inbox", "stream_id"
+            db_conn, "device_max_stream_id", "stream_id"
+        )
+        self._public_room_id_gen = StreamIdGenerator(
+            db_conn, "public_room_list_stream", "stream_id"
         )
 
         self._transaction_id_gen = IdGenerator(db_conn, "sent_transactions", "id")
@@ -182,6 +185,30 @@ class DataStore(RoomMemberStore, RoomStore,
             prefilled_cache=push_rules_prefill,
         )
 
+        max_device_inbox_id = self._device_inbox_id_gen.get_current_token()
+        device_inbox_prefill, min_device_inbox_id = self._get_cache_dict(
+            db_conn, "device_inbox",
+            entity_column="user_id",
+            stream_column="stream_id",
+            max_value=max_device_inbox_id
+        )
+        self._device_inbox_stream_cache = StreamChangeCache(
+            "DeviceInboxStreamChangeCache", min_device_inbox_id,
+            prefilled_cache=device_inbox_prefill,
+        )
+        # The federation outbox and the local device inbox uses the same
+        # stream_id generator.
+        device_outbox_prefill, min_device_outbox_id = self._get_cache_dict(
+            db_conn, "device_federation_outbox",
+            entity_column="destination",
+            stream_column="stream_id",
+            max_value=max_device_inbox_id,
+        )
+        self._device_federation_outbox_stream_cache = StreamChangeCache(
+            "DeviceFederationOutboxStreamChangeCache", min_device_outbox_id,
+            prefilled_cache=device_outbox_prefill,
+        )
+
         cur = LoggingTransaction(
             db_conn.cursor(),
             name="_find_stream_orderings_for_times_txn",
@@ -195,6 +222,8 @@ class DataStore(RoomMemberStore, RoomStore,
             self._find_stream_orderings_for_times, 60 * 60 * 1000
         )
 
+        self._stream_order_on_start = self.get_room_max_stream_ordering()
+
         super(DataStore, self).__init__(hs)
 
     def take_presence_startup_info(self):
diff --git a/synapse/storage/background_updates.py b/synapse/storage/background_updates.py
index 30d0e4c5dc..94b2bcc54a 100644
--- a/synapse/storage/background_updates.py
+++ b/synapse/storage/background_updates.py
@@ -133,10 +133,12 @@ class BackgroundUpdateStore(SQLBaseStore):
             updates = yield self._simple_select_list(
                 "background_updates",
                 keyvalues=None,
-                retcols=("update_name",),
+                retcols=("update_name", "depends_on"),
             )
+            in_flight = set(update["update_name"] for update in updates)
             for update in updates:
-                self._background_update_queue.append(update['update_name'])
+                if update["depends_on"] not in in_flight:
+                    self._background_update_queue.append(update['update_name'])
 
         if not self._background_update_queue:
             # no work left to do
@@ -217,7 +219,7 @@ class BackgroundUpdateStore(SQLBaseStore):
         self._background_update_handlers[update_name] = update_handler
 
     def register_background_index_update(self, update_name, index_name,
-                                         table, columns):
+                                         table, columns, where_clause=None):
         """Helper for store classes to do a background index addition
 
         To use:
@@ -241,14 +243,20 @@ class BackgroundUpdateStore(SQLBaseStore):
             conc = True
         else:
             conc = False
-
-        sql = "CREATE INDEX %(conc)s %(name)s ON %(table)s (%(columns)s)" \
-              % {
-                  "conc": "CONCURRENTLY" if conc else "",
-                  "name": index_name,
-                  "table": table,
-                  "columns": ", ".join(columns),
-              }
+            # We don't use partial indices on SQLite as it wasn't introduced
+            # until 3.8, and wheezy has 3.7
+            where_clause = None
+
+        sql = (
+            "CREATE INDEX %(conc)s %(name)s ON %(table)s (%(columns)s)"
+            " %(where_clause)s"
+        ) % {
+            "conc": "CONCURRENTLY" if conc else "",
+            "name": index_name,
+            "table": table,
+            "columns": ", ".join(columns),
+            "where_clause": "WHERE " + where_clause if where_clause else ""
+        }
 
         def create_index_concurrently(conn):
             conn.rollback()
diff --git a/synapse/storage/deviceinbox.py b/synapse/storage/deviceinbox.py
index 68116b0394..f640e73714 100644
--- a/synapse/storage/deviceinbox.py
+++ b/synapse/storage/deviceinbox.py
@@ -27,63 +27,172 @@ logger = logging.getLogger(__name__)
 class DeviceInboxStore(SQLBaseStore):
 
     @defer.inlineCallbacks
-    def add_messages_to_device_inbox(self, messages_by_user_then_device):
-        """
+    def add_messages_to_device_inbox(self, local_messages_by_user_then_device,
+                                     remote_messages_by_destination):
+        """Used to send messages from this server.
+
         Args:
-            messages_by_user_and_device(dict):
+            sender_user_id(str): The ID of the user sending these messages.
+            local_messages_by_user_and_device(dict):
                 Dictionary of user_id to device_id to message.
+            remote_messages_by_destination(dict):
+                Dictionary of destination server_name to the EDU JSON to send.
         Returns:
             A deferred stream_id that resolves when the messages have been
             inserted.
         """
 
-        def select_devices_txn(txn, user_id, devices):
-            if not devices:
-                return []
-            sql = (
-                "SELECT user_id, device_id FROM devices"
-                " WHERE user_id = ? AND device_id IN ("
-                + ",".join("?" * len(devices))
-                + ")"
+        def add_messages_txn(txn, now_ms, stream_id):
+            # Add the local messages directly to the local inbox.
+            self._add_messages_to_local_device_inbox_txn(
+                txn, stream_id, local_messages_by_user_then_device
             )
-            # TODO: Maybe this needs to be done in batches if there are
-            # too many local devices for a given user.
-            args = [user_id] + devices
-            txn.execute(sql, args)
-            return [tuple(row) for row in txn.fetchall()]
-
-        def add_messages_to_device_inbox_txn(txn, stream_id):
-            local_users_and_devices = set()
-            for user_id, messages_by_device in messages_by_user_then_device.items():
-                local_users_and_devices.update(
-                    select_devices_txn(txn, user_id, messages_by_device.keys())
-                )
 
+            # Add the remote messages to the federation outbox.
+            # We'll send them to a remote server when we next send a
+            # federation transaction to that destination.
             sql = (
-                "INSERT INTO device_inbox"
-                " (user_id, device_id, stream_id, message_json)"
+                "INSERT INTO device_federation_outbox"
+                " (destination, stream_id, queued_ts, messages_json)"
                 " VALUES (?,?,?,?)"
             )
             rows = []
-            for user_id, messages_by_device in messages_by_user_then_device.items():
-                for device_id, message in messages_by_device.items():
-                    message_json = ujson.dumps(message)
-                    # Only insert into the local inbox if the device exists on
-                    # this server
-                    if (user_id, device_id) in local_users_and_devices:
-                        rows.append((user_id, device_id, stream_id, message_json))
-
+            for destination, edu in remote_messages_by_destination.items():
+                edu_json = ujson.dumps(edu)
+                rows.append((destination, stream_id, now_ms, edu_json))
             txn.executemany(sql, rows)
 
         with self._device_inbox_id_gen.get_next() as stream_id:
+            now_ms = self.clock.time_msec()
             yield self.runInteraction(
                 "add_messages_to_device_inbox",
-                add_messages_to_device_inbox_txn,
-                stream_id
+                add_messages_txn,
+                now_ms,
+                stream_id,
             )
+            for user_id in local_messages_by_user_then_device.keys():
+                self._device_inbox_stream_cache.entity_has_changed(
+                    user_id, stream_id
+                )
+            for destination in remote_messages_by_destination.keys():
+                self._device_federation_outbox_stream_cache.entity_has_changed(
+                    destination, stream_id
+                )
 
         defer.returnValue(self._device_inbox_id_gen.get_current_token())
 
+    @defer.inlineCallbacks
+    def add_messages_from_remote_to_device_inbox(
+        self, origin, message_id, local_messages_by_user_then_device
+    ):
+        def add_messages_txn(txn, now_ms, stream_id):
+            # Check if we've already inserted a matching message_id for that
+            # origin. This can happen if the origin doesn't receive our
+            # acknowledgement from the first time we received the message.
+            already_inserted = self._simple_select_one_txn(
+                txn, table="device_federation_inbox",
+                keyvalues={"origin": origin, "message_id": message_id},
+                retcols=("message_id",),
+                allow_none=True,
+            )
+            if already_inserted is not None:
+                return
+
+            # Add an entry for this message_id so that we know we've processed
+            # it.
+            self._simple_insert_txn(
+                txn, table="device_federation_inbox",
+                values={
+                    "origin": origin,
+                    "message_id": message_id,
+                    "received_ts": now_ms,
+                },
+            )
+
+            # Add the messages to the approriate local device inboxes so that
+            # they'll be sent to the devices when they next sync.
+            self._add_messages_to_local_device_inbox_txn(
+                txn, stream_id, local_messages_by_user_then_device
+            )
+
+        with self._device_inbox_id_gen.get_next() as stream_id:
+            now_ms = self.clock.time_msec()
+            yield self.runInteraction(
+                "add_messages_from_remote_to_device_inbox",
+                add_messages_txn,
+                now_ms,
+                stream_id,
+            )
+            for user_id in local_messages_by_user_then_device.keys():
+                self._device_inbox_stream_cache.entity_has_changed(
+                    user_id, stream_id
+                )
+
+        defer.returnValue(stream_id)
+
+    def _add_messages_to_local_device_inbox_txn(self, txn, stream_id,
+                                                messages_by_user_then_device):
+        sql = (
+            "UPDATE device_max_stream_id"
+            " SET stream_id = ?"
+            " WHERE stream_id < ?"
+        )
+        txn.execute(sql, (stream_id, stream_id))
+
+        local_by_user_then_device = {}
+        for user_id, messages_by_device in messages_by_user_then_device.items():
+            messages_json_for_user = {}
+            devices = messages_by_device.keys()
+            if len(devices) == 1 and devices[0] == "*":
+                # Handle wildcard device_ids.
+                sql = (
+                    "SELECT device_id FROM devices"
+                    " WHERE user_id = ?"
+                )
+                txn.execute(sql, (user_id,))
+                message_json = ujson.dumps(messages_by_device["*"])
+                for row in txn.fetchall():
+                    # Add the message for all devices for this user on this
+                    # server.
+                    device = row[0]
+                    messages_json_for_user[device] = message_json
+            else:
+                if not devices:
+                    continue
+                sql = (
+                    "SELECT device_id FROM devices"
+                    " WHERE user_id = ? AND device_id IN ("
+                    + ",".join("?" * len(devices))
+                    + ")"
+                )
+                # TODO: Maybe this needs to be done in batches if there are
+                # too many local devices for a given user.
+                txn.execute(sql, [user_id] + devices)
+                for row in txn.fetchall():
+                    # Only insert into the local inbox if the device exists on
+                    # this server
+                    device = row[0]
+                    message_json = ujson.dumps(messages_by_device[device])
+                    messages_json_for_user[device] = message_json
+
+            if messages_json_for_user:
+                local_by_user_then_device[user_id] = messages_json_for_user
+
+        if not local_by_user_then_device:
+            return
+
+        sql = (
+            "INSERT INTO device_inbox"
+            " (user_id, device_id, stream_id, message_json)"
+            " VALUES (?,?,?,?)"
+        )
+        rows = []
+        for user_id, messages_by_device in local_by_user_then_device.items():
+            for device_id, message_json in messages_by_device.items():
+                rows.append((user_id, device_id, stream_id, message_json))
+
+        txn.executemany(sql, rows)
+
     def get_new_messages_for_device(
         self, user_id, device_id, last_stream_id, current_stream_id, limit=100
     ):
@@ -97,6 +206,12 @@ class DeviceInboxStore(SQLBaseStore):
             Deferred ([dict], int): List of messages for the device and where
                 in the stream the messages got to.
         """
+        has_changed = self._device_inbox_stream_cache.has_entity_changed(
+            user_id, last_stream_id
+        )
+        if not has_changed:
+            return defer.succeed(([], current_stream_id))
+
         def get_new_messages_for_device_txn(txn):
             sql = (
                 "SELECT stream_id, message_json FROM device_inbox"
@@ -182,3 +297,71 @@ class DeviceInboxStore(SQLBaseStore):
 
     def get_to_device_stream_token(self):
         return self._device_inbox_id_gen.get_current_token()
+
+    def get_new_device_msgs_for_remote(
+        self, destination, last_stream_id, current_stream_id, limit=100
+    ):
+        """
+        Args:
+            destination(str): The name of the remote server.
+            last_stream_id(int): The last position of the device message stream
+                that the server sent up to.
+            current_stream_id(int): The current position of the device
+                message stream.
+        Returns:
+            Deferred ([dict], int): List of messages for the device and where
+                in the stream the messages got to.
+        """
+
+        has_changed = self._device_federation_outbox_stream_cache.has_entity_changed(
+            destination, last_stream_id
+        )
+        if not has_changed or last_stream_id == current_stream_id:
+            return defer.succeed(([], current_stream_id))
+
+        def get_new_messages_for_remote_destination_txn(txn):
+            sql = (
+                "SELECT stream_id, messages_json FROM device_federation_outbox"
+                " WHERE destination = ?"
+                " AND ? < stream_id AND stream_id <= ?"
+                " ORDER BY stream_id ASC"
+                " LIMIT ?"
+            )
+            txn.execute(sql, (
+                destination, last_stream_id, current_stream_id, limit
+            ))
+            messages = []
+            for row in txn.fetchall():
+                stream_pos = row[0]
+                messages.append(ujson.loads(row[1]))
+            if len(messages) < limit:
+                stream_pos = current_stream_id
+            return (messages, stream_pos)
+
+        return self.runInteraction(
+            "get_new_device_msgs_for_remote",
+            get_new_messages_for_remote_destination_txn,
+        )
+
+    def delete_device_msgs_for_remote(self, destination, up_to_stream_id):
+        """Used to delete messages when the remote destination acknowledges
+        their receipt.
+
+        Args:
+            destination(str): The destination server_name
+            up_to_stream_id(int): Where to delete messages up to.
+        Returns:
+            A deferred that resolves when the messages have been deleted.
+        """
+        def delete_messages_for_remote_destination_txn(txn):
+            sql = (
+                "DELETE FROM device_federation_outbox"
+                " WHERE destination = ?"
+                " AND stream_id <= ?"
+            )
+            txn.execute(sql, (destination, up_to_stream_id))
+
+        return self.runInteraction(
+            "delete_device_msgs_for_remote",
+            delete_messages_for_remote_destination_txn
+        )
diff --git a/synapse/storage/devices.py b/synapse/storage/devices.py
index afd6530cab..17920d4480 100644
--- a/synapse/storage/devices.py
+++ b/synapse/storage/devices.py
@@ -54,8 +54,12 @@ class DeviceStore(SQLBaseStore):
                 or_ignore=ignore_if_known,
             )
         except Exception as e:
-            logger.error("store_device with device_id=%s failed: %s",
-                         device_id, e)
+            logger.error("store_device with device_id=%s(%r) user_id=%s(%r)"
+                         " display_name=%s(%r) failed: %s",
+                         type(device_id).__name__, device_id,
+                         type(user_id).__name__, user_id,
+                         type(initial_device_display_name).__name__,
+                         initial_device_display_name, e)
             raise StoreError(500, "Problem storing device.")
 
     def get_device(self, user_id, device_id):
diff --git a/synapse/storage/event_federation.py b/synapse/storage/event_federation.py
index 0827946207..3d62451de9 100644
--- a/synapse/storage/event_federation.py
+++ b/synapse/storage/event_federation.py
@@ -16,6 +16,7 @@
 from twisted.internet import defer
 
 from ._base import SQLBaseStore
+from synapse.api.errors import StoreError
 from synapse.util.caches.descriptors import cached
 from unpaddedbase64 import encode_base64
 
@@ -36,6 +37,13 @@ class EventFederationStore(SQLBaseStore):
     and backfilling from another server respectively.
     """
 
+    def __init__(self, hs):
+        super(EventFederationStore, self).__init__(hs)
+
+        hs.get_clock().looping_call(
+            self._delete_old_forward_extrem_cache, 60 * 60 * 1000
+        )
+
     def get_auth_chain(self, event_ids):
         return self.get_auth_chain_ids(event_ids).addCallback(self._get_events)
 
@@ -270,6 +278,37 @@ class EventFederationStore(SQLBaseStore):
             ]
         )
 
+        # We now insert into stream_ordering_to_exterm a mapping from room_id,
+        # new stream_ordering to new forward extremeties in the room.
+        # This allows us to later efficiently look up the forward extremeties
+        # for a room before a given stream_ordering
+        max_stream_ord = max(
+            ev.internal_metadata.stream_ordering for ev in events
+        )
+        new_extrem = {}
+        for room_id in events_by_room:
+            event_ids = self._simple_select_onecol_txn(
+                txn,
+                table="event_forward_extremities",
+                keyvalues={"room_id": room_id},
+                retcol="event_id",
+            )
+            new_extrem[room_id] = event_ids
+
+        self._simple_insert_many_txn(
+            txn,
+            table="stream_ordering_to_exterm",
+            values=[
+                {
+                    "room_id": room_id,
+                    "event_id": event_id,
+                    "stream_ordering": max_stream_ord,
+                }
+                for room_id, extrem_evs in new_extrem.items()
+                for event_id in extrem_evs
+            ]
+        )
+
         query = (
             "INSERT INTO event_backward_extremities (event_id, room_id)"
             " SELECT ?, ? WHERE NOT EXISTS ("
@@ -305,6 +344,76 @@ class EventFederationStore(SQLBaseStore):
                 self.get_latest_event_ids_in_room.invalidate, (room_id,)
             )
 
+    def get_forward_extremeties_for_room(self, room_id, stream_ordering):
+        # We want to make the cache more effective, so we clamp to the last
+        # change before the given ordering.
+        last_change = self._events_stream_cache.get_max_pos_of_last_change(room_id)
+
+        # We don't always have a full stream_to_exterm_id table, e.g. after
+        # the upgrade that introduced it, so we make sure we never ask for a
+        # try and pin to a stream_ordering from before a restart
+        last_change = max(self._stream_order_on_start, last_change)
+
+        if last_change > self.stream_ordering_month_ago:
+            stream_ordering = min(last_change, stream_ordering)
+
+        return self._get_forward_extremeties_for_room(room_id, stream_ordering)
+
+    @cached(max_entries=5000, num_args=2)
+    def _get_forward_extremeties_for_room(self, room_id, stream_ordering):
+        """For a given room_id and stream_ordering, return the forward
+        extremeties of the room at that point in "time".
+
+        Throws a StoreError if we have since purged the index for
+        stream_orderings from that point.
+        """
+
+        if stream_ordering <= self.stream_ordering_month_ago:
+            raise StoreError(400, "stream_ordering too old")
+
+        sql = ("""
+                SELECT event_id FROM stream_ordering_to_exterm
+                INNER JOIN (
+                    SELECT room_id, MAX(stream_ordering) AS stream_ordering
+                    FROM stream_ordering_to_exterm
+                    WHERE stream_ordering <= ? GROUP BY room_id
+                ) AS rms USING (room_id, stream_ordering)
+                WHERE room_id = ?
+        """)
+
+        def get_forward_extremeties_for_room_txn(txn):
+            txn.execute(sql, (stream_ordering, room_id))
+            rows = txn.fetchall()
+            return [event_id for event_id, in rows]
+
+        return self.runInteraction(
+            "get_forward_extremeties_for_room",
+            get_forward_extremeties_for_room_txn
+        )
+
+    def _delete_old_forward_extrem_cache(self):
+        def _delete_old_forward_extrem_cache_txn(txn):
+            # Delete entries older than a month, while making sure we don't delete
+            # the only entries for a room.
+            sql = ("""
+                DELETE FROM stream_ordering_to_exterm
+                WHERE
+                (
+                    SELECT max(stream_ordering) AS stream_ordering
+                    FROM stream_ordering_to_exterm
+                    WHERE room_id = stream_ordering_to_exterm.room_id
+                ) > ?
+                AND stream_ordering < ?
+            """)
+            txn.execute(
+                sql,
+                (self.stream_ordering_month_ago, self.stream_ordering_month_ago,)
+            )
+        return self.runInteraction(
+            "_delete_old_forward_extrem_cache",
+            _delete_old_forward_extrem_cache_txn
+        )
+
     def get_backfill_events(self, room_id, event_list, limit):
         """Get a list of Events for a given topic that occurred before (and
         including) the events in event_list. Return a list of max size `limit`
diff --git a/synapse/storage/event_push_actions.py b/synapse/storage/event_push_actions.py
index eb15fb751b..9cd923eb93 100644
--- a/synapse/storage/event_push_actions.py
+++ b/synapse/storage/event_push_actions.py
@@ -26,10 +26,19 @@ logger = logging.getLogger(__name__)
 
 
 class EventPushActionsStore(SQLBaseStore):
+    EPA_HIGHLIGHT_INDEX = "epa_highlight_index"
+
     def __init__(self, hs):
         self.stream_ordering_month_ago = None
         super(EventPushActionsStore, self).__init__(hs)
 
+        self.register_background_index_update(
+            self.EPA_HIGHLIGHT_INDEX,
+            index_name="event_push_actions_u_highlight",
+            table="event_push_actions",
+            columns=["user_id", "stream_ordering"],
+        )
+
     def _set_push_actions_for_event_and_users_txn(self, txn, event, tuples):
         """
         Args:
@@ -338,20 +347,29 @@ class EventPushActionsStore(SQLBaseStore):
         defer.returnValue(notifs[:limit])
 
     @defer.inlineCallbacks
-    def get_push_actions_for_user(self, user_id, before=None, limit=50):
+    def get_push_actions_for_user(self, user_id, before=None, limit=50,
+                                  only_highlight=False):
         def f(txn):
             before_clause = ""
             if before:
-                before_clause = "AND stream_ordering < ?"
+                before_clause = "AND epa.stream_ordering < ?"
                 args = [user_id, before, limit]
             else:
                 args = [user_id, limit]
+
+            if only_highlight:
+                if len(before_clause) > 0:
+                    before_clause += " "
+                before_clause += "AND epa.highlight = 1"
+
+            # NB. This assumes event_ids are globally unique since
+            # it makes the query easier to index
             sql = (
                 "SELECT epa.event_id, epa.room_id,"
                 " epa.stream_ordering, epa.topological_ordering,"
                 " epa.actions, epa.profile_tag, e.received_ts"
                 " FROM event_push_actions epa, events e"
-                " WHERE epa.room_id = e.room_id AND epa.event_id = e.event_id"
+                " WHERE epa.event_id = e.event_id"
                 " AND epa.user_id = ? %s"
                 " ORDER BY epa.stream_ordering DESC"
                 " LIMIT ?"
diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index 1a7d4c5199..6dc46fa50f 100644
--- a/synapse/storage/events.py
+++ b/synapse/storage/events.py
@@ -189,6 +189,14 @@ class EventsStore(SQLBaseStore):
             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",
+        )
+
         self._event_persist_queue = _EventPeristenceQueue()
 
     def persist_events(self, events_and_contexts, backfilled=False):
@@ -497,7 +505,11 @@ class EventsStore(SQLBaseStore):
 
                 # insert into the state_group, state_groups_state and
                 # event_to_state_groups tables.
-                self._store_mult_state_groups_txn(txn, ((event, context),))
+                try:
+                    self._store_mult_state_groups_txn(txn, ((event, context),))
+                except Exception:
+                    logger.exception("")
+                    raise
 
                 metadata_json = encode_json(
                     event.internal_metadata.get_dict()
@@ -1543,6 +1555,9 @@ class EventsStore(SQLBaseStore):
         )
         event_rows = txn.fetchall()
 
+        for event_id, state_key in event_rows:
+            txn.call_after(self._get_state_group_for_event.invalidate, (event_id,))
+
         # We calculate the new entries for the backward extremeties by finding
         # all events that point to events that are to be purged
         txn.execute(
@@ -1582,7 +1597,66 @@ class EventsStore(SQLBaseStore):
             " GROUP BY state_group HAVING MAX(topological_ordering) < ?",
             (room_id, topological_ordering, topological_ordering)
         )
+
         state_rows = txn.fetchall()
+        state_groups_to_delete = [sg for sg, in state_rows]
+
+        # Now we get all the state groups that rely on these state groups
+        new_state_edges = []
+        chunks = [
+            state_groups_to_delete[i:i + 100]
+            for i in xrange(0, len(state_groups_to_delete), 100)
+        ]
+        for chunk in chunks:
+            rows = self._simple_select_many_txn(
+                txn,
+                table="state_group_edges",
+                column="prev_state_group",
+                iterable=chunk,
+                retcols=["state_group"],
+                keyvalues={},
+            )
+            new_state_edges.extend(row["state_group"] for row in rows)
+
+        # Now we turn the state groups that reference to-be-deleted state groups
+        # to non delta versions.
+        for new_state_edge in new_state_edges:
+            curr_state = self._get_state_groups_from_groups_txn(
+                txn, [new_state_edge], types=None
+            )
+            curr_state = curr_state[new_state_edge]
+
+            self._simple_delete_txn(
+                txn,
+                table="state_groups_state",
+                keyvalues={
+                    "state_group": new_state_edge,
+                }
+            )
+
+            self._simple_delete_txn(
+                txn,
+                table="state_group_edges",
+                keyvalues={
+                    "state_group": new_state_edge,
+                }
+            )
+
+            self._simple_insert_many_txn(
+                txn,
+                table="state_groups_state",
+                values=[
+                    {
+                        "state_group": new_state_edge,
+                        "room_id": room_id,
+                        "type": key[0],
+                        "state_key": key[1],
+                        "event_id": state_id,
+                    }
+                    for key, state_id in curr_state.items()
+                ],
+            )
+
         txn.executemany(
             "DELETE FROM state_groups_state WHERE state_group = ?",
             state_rows
diff --git a/synapse/storage/prepare_database.py b/synapse/storage/prepare_database.py
index b94ce7bea1..7efbe51cda 100644
--- a/synapse/storage/prepare_database.py
+++ b/synapse/storage/prepare_database.py
@@ -25,7 +25,7 @@ logger = logging.getLogger(__name__)
 
 # Remember to update this number every time a change is made to database
 # schema files, so the users will be informed on server restarts.
-SCHEMA_VERSION = 34
+SCHEMA_VERSION = 35
 
 dir_path = os.path.abspath(os.path.dirname(__file__))
 
@@ -242,7 +242,7 @@ def _upgrade_existing_database(cur, current_version, applied_delta_files,
                     module = imp.load_source(
                         module_name, absolute_path, python_file
                     )
-                logger.debug("Running script %s", relative_path)
+                logger.info("Running script %s", relative_path)
                 module.run_create(cur, database_engine)
                 if not is_empty:
                     module.run_upgrade(cur, database_engine, config=config)
@@ -253,7 +253,7 @@ def _upgrade_existing_database(cur, current_version, applied_delta_files,
                 pass
             elif ext == ".sql":
                 # A plain old .sql file, just read and execute it
-                logger.debug("Applying schema %s", relative_path)
+                logger.info("Applying schema %s", relative_path)
                 executescript(cur, absolute_path)
             else:
                 # Not a valid delta file.
diff --git a/synapse/storage/room.py b/synapse/storage/room.py
index 8251f58670..2ef13d7403 100644
--- a/synapse/storage/room.py
+++ b/synapse/storage/room.py
@@ -48,15 +48,31 @@ class RoomStore(SQLBaseStore):
             StoreError if the room could not be stored.
         """
         try:
-            yield self._simple_insert(
-                "rooms",
-                {
-                    "room_id": room_id,
-                    "creator": room_creator_user_id,
-                    "is_public": is_public,
-                },
-                desc="store_room",
-            )
+            def store_room_txn(txn, next_id):
+                self._simple_insert_txn(
+                    txn,
+                    "rooms",
+                    {
+                        "room_id": room_id,
+                        "creator": room_creator_user_id,
+                        "is_public": is_public,
+                    },
+                )
+                if is_public:
+                    self._simple_insert_txn(
+                        txn,
+                        table="public_room_list_stream",
+                        values={
+                            "stream_id": next_id,
+                            "room_id": room_id,
+                            "visibility": is_public,
+                        }
+                    )
+            with self._public_room_id_gen.get_next() as next_id:
+                yield self.runInteraction(
+                    "store_room_txn",
+                    store_room_txn, next_id,
+                )
         except Exception as e:
             logger.error("store_room with room_id=%s failed: %s", room_id, e)
             raise StoreError(500, "Problem creating room.")
@@ -77,13 +93,45 @@ class RoomStore(SQLBaseStore):
             allow_none=True,
         )
 
+    @defer.inlineCallbacks
     def set_room_is_public(self, room_id, is_public):
-        return self._simple_update_one(
-            table="rooms",
-            keyvalues={"room_id": room_id},
-            updatevalues={"is_public": is_public},
-            desc="set_room_is_public",
-        )
+        def set_room_is_public_txn(txn, next_id):
+            self._simple_update_one_txn(
+                txn,
+                table="rooms",
+                keyvalues={"room_id": room_id},
+                updatevalues={"is_public": is_public},
+            )
+
+            entries = self._simple_select_list_txn(
+                txn,
+                table="public_room_list_stream",
+                keyvalues={"room_id": room_id},
+                retcols=("stream_id", "visibility"),
+            )
+
+            entries.sort(key=lambda r: r["stream_id"])
+
+            add_to_stream = True
+            if entries:
+                add_to_stream = bool(entries[-1]["visibility"]) != is_public
+
+            if add_to_stream:
+                self._simple_insert_txn(
+                    txn,
+                    table="public_room_list_stream",
+                    values={
+                        "stream_id": next_id,
+                        "room_id": room_id,
+                        "visibility": is_public,
+                    }
+                )
+
+        with self._public_room_id_gen.get_next() as next_id:
+            yield self.runInteraction(
+                "set_room_is_public",
+                set_room_is_public_txn, next_id,
+            )
 
     def get_public_room_ids(self):
         return self._simple_select_onecol(
@@ -207,3 +255,71 @@ class RoomStore(SQLBaseStore):
             },
             desc="add_event_report"
         )
+
+    def get_current_public_room_stream_id(self):
+        return self._public_room_id_gen.get_current_token()
+
+    def get_public_room_ids_at_stream_id(self, stream_id):
+        return self.runInteraction(
+            "get_public_room_ids_at_stream_id",
+            self.get_public_room_ids_at_stream_id_txn, stream_id
+        )
+
+    def get_public_room_ids_at_stream_id_txn(self, txn, stream_id):
+        return {
+            rm
+            for rm, vis in self.get_published_at_stream_id_txn(txn, stream_id).items()
+            if vis
+        }
+
+    def get_published_at_stream_id_txn(self, txn, stream_id):
+        sql = ("""
+            SELECT room_id, visibility FROM public_room_list_stream
+            INNER JOIN (
+                SELECT room_id, max(stream_id) AS stream_id
+                FROM public_room_list_stream
+                WHERE stream_id <= ?
+                GROUP BY room_id
+            ) grouped USING (room_id, stream_id)
+        """)
+
+        txn.execute(sql, (stream_id,))
+        return dict(txn.fetchall())
+
+    def get_public_room_changes(self, prev_stream_id, new_stream_id):
+        def get_public_room_changes_txn(txn):
+            then_rooms = self.get_public_room_ids_at_stream_id_txn(txn, prev_stream_id)
+
+            now_rooms_dict = self.get_published_at_stream_id_txn(txn, new_stream_id)
+
+            now_rooms_visible = set(
+                rm for rm, vis in now_rooms_dict.items() if vis
+            )
+            now_rooms_not_visible = set(
+                rm for rm, vis in now_rooms_dict.items() if not vis
+            )
+
+            newly_visible = now_rooms_visible - then_rooms
+            newly_unpublished = now_rooms_not_visible & then_rooms
+
+            return newly_visible, newly_unpublished
+
+        return self.runInteraction(
+            "get_public_room_changes", get_public_room_changes_txn
+        )
+
+    def get_all_new_public_rooms(self, prev_id, current_id, limit):
+        def get_all_new_public_rooms(txn):
+            sql = ("""
+                SELECT stream_id, room_id, visibility FROM public_room_list_stream
+                WHERE stream_id > ? AND stream_id <= ?
+                ORDER BY stream_id ASC
+                LIMIT ?
+            """)
+
+            txn.execute(sql, (prev_id, current_id, limit,))
+            return txn.fetchall()
+
+        return self.runInteraction(
+            "get_all_new_public_rooms", get_all_new_public_rooms
+        )
diff --git a/synapse/storage/schema/delta/22/receipts_index.sql b/synapse/storage/schema/delta/22/receipts_index.sql
index 7bc061dff6..bfc0b3bcaa 100644
--- a/synapse/storage/schema/delta/22/receipts_index.sql
+++ b/synapse/storage/schema/delta/22/receipts_index.sql
@@ -13,6 +13,10 @@
  * limitations under the License.
  */
 
+/** Using CREATE INDEX directly is deprecated in favour of using background
+ * update see synapse/storage/schema/delta/33/access_tokens_device_index.sql
+ * and synapse/storage/registration.py for an example using
+ * "access_tokens_device_index" **/
 CREATE INDEX receipts_linearized_room_stream ON receipts_linearized(
     room_id, stream_id
 );
diff --git a/synapse/storage/schema/delta/28/events_room_stream.sql b/synapse/storage/schema/delta/28/events_room_stream.sql
index 200c35e6e2..36609475f1 100644
--- a/synapse/storage/schema/delta/28/events_room_stream.sql
+++ b/synapse/storage/schema/delta/28/events_room_stream.sql
@@ -13,4 +13,8 @@
  * limitations under the License.
 */
 
+/** Using CREATE INDEX directly is deprecated in favour of using background
+ * update see synapse/storage/schema/delta/33/access_tokens_device_index.sql
+ * and synapse/storage/registration.py for an example using
+ * "access_tokens_device_index" **/
 CREATE INDEX events_room_stream on events(room_id, stream_ordering);
diff --git a/synapse/storage/schema/delta/28/public_roms_index.sql b/synapse/storage/schema/delta/28/public_roms_index.sql
index ba62a974a4..6c1fd68c5b 100644
--- a/synapse/storage/schema/delta/28/public_roms_index.sql
+++ b/synapse/storage/schema/delta/28/public_roms_index.sql
@@ -13,4 +13,8 @@
  * limitations under the License.
 */
 
+/** Using CREATE INDEX directly is deprecated in favour of using background
+ * update see synapse/storage/schema/delta/33/access_tokens_device_index.sql
+ * and synapse/storage/registration.py for an example using
+ * "access_tokens_device_index" **/
 CREATE INDEX public_room_index on rooms(is_public);
diff --git a/synapse/storage/schema/delta/28/receipts_user_id_index.sql b/synapse/storage/schema/delta/28/receipts_user_id_index.sql
index 452a1b3c6c..cb84c69baa 100644
--- a/synapse/storage/schema/delta/28/receipts_user_id_index.sql
+++ b/synapse/storage/schema/delta/28/receipts_user_id_index.sql
@@ -13,6 +13,10 @@
  * limitations under the License.
  */
 
+/** Using CREATE INDEX directly is deprecated in favour of using background
+ * update see synapse/storage/schema/delta/33/access_tokens_device_index.sql
+ * and synapse/storage/registration.py for an example using
+ * "access_tokens_device_index" **/
 CREATE INDEX receipts_linearized_user ON receipts_linearized(
     user_id
 );
diff --git a/synapse/storage/schema/delta/29/push_actions.sql b/synapse/storage/schema/delta/29/push_actions.sql
index 7e7b09820a..84b21cf813 100644
--- a/synapse/storage/schema/delta/29/push_actions.sql
+++ b/synapse/storage/schema/delta/29/push_actions.sql
@@ -26,6 +26,10 @@ UPDATE event_push_actions SET stream_ordering = (
 
 UPDATE event_push_actions SET notif = 1, highlight = 0;
 
+/** Using CREATE INDEX directly is deprecated in favour of using background
+ * update see synapse/storage/schema/delta/33/access_tokens_device_index.sql
+ * and synapse/storage/registration.py for an example using
+ * "access_tokens_device_index" **/
 CREATE INDEX event_push_actions_rm_tokens on event_push_actions(
     user_id, room_id, topological_ordering, stream_ordering
 );
diff --git a/synapse/storage/schema/delta/31/pushers_index.sql b/synapse/storage/schema/delta/31/pushers_index.sql
index 9027bccc69..a82add88fd 100644
--- a/synapse/storage/schema/delta/31/pushers_index.sql
+++ b/synapse/storage/schema/delta/31/pushers_index.sql
@@ -13,6 +13,10 @@
  * limitations under the License.
  */
 
+/** Using CREATE INDEX directly is deprecated in favour of using background
+ * update see synapse/storage/schema/delta/33/access_tokens_device_index.sql
+ * and synapse/storage/registration.py for an example using
+ * "access_tokens_device_index" **/
  CREATE INDEX event_push_actions_stream_ordering on event_push_actions(
      stream_ordering, user_id
  );
diff --git a/synapse/storage/schema/delta/35/add_state_index.sql b/synapse/storage/schema/delta/35/add_state_index.sql
new file mode 100644
index 0000000000..0fce26345b
--- /dev/null
+++ b/synapse/storage/schema/delta/35/add_state_index.sql
@@ -0,0 +1,20 @@
+/* Copyright 2016 OpenMarket 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.
+ */
+
+
+ALTER TABLE background_updates ADD COLUMN depends_on TEXT;
+
+INSERT into background_updates (update_name, progress_json, depends_on)
+    VALUES ('state_group_state_type_index', '{}', 'state_group_state_deduplication');
diff --git a/synapse/storage/schema/delta/35/contains_url.sql b/synapse/storage/schema/delta/35/contains_url.sql
new file mode 100644
index 0000000000..6cd123027b
--- /dev/null
+++ b/synapse/storage/schema/delta/35/contains_url.sql
@@ -0,0 +1,17 @@
+/* Copyright 2016 OpenMarket 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.
+ */
+
+ INSERT into background_updates (update_name, progress_json)
+     VALUES ('event_contains_url_index', '{}');
diff --git a/synapse/storage/schema/delta/35/device_outbox.sql b/synapse/storage/schema/delta/35/device_outbox.sql
new file mode 100644
index 0000000000..17e6c43105
--- /dev/null
+++ b/synapse/storage/schema/delta/35/device_outbox.sql
@@ -0,0 +1,39 @@
+/* Copyright 2016 OpenMarket 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.
+ */
+
+DROP TABLE IF EXISTS device_federation_outbox;
+CREATE TABLE device_federation_outbox (
+    destination TEXT NOT NULL,
+    stream_id BIGINT NOT NULL,
+    queued_ts BIGINT NOT NULL,
+    messages_json TEXT NOT NULL
+);
+
+
+DROP INDEX IF EXISTS device_federation_outbox_destination_id;
+CREATE INDEX device_federation_outbox_destination_id
+    ON device_federation_outbox(destination, stream_id);
+
+
+DROP TABLE IF EXISTS device_federation_inbox;
+CREATE TABLE device_federation_inbox (
+    origin TEXT NOT NULL,
+    message_id TEXT NOT NULL,
+    received_ts BIGINT NOT NULL
+);
+
+DROP INDEX IF EXISTS device_federation_inbox_sender_id;
+CREATE INDEX device_federation_inbox_sender_id
+    ON device_federation_inbox(origin, message_id);
diff --git a/synapse/storage/schema/delta/35/device_stream_id.sql b/synapse/storage/schema/delta/35/device_stream_id.sql
new file mode 100644
index 0000000000..7ab7d942e2
--- /dev/null
+++ b/synapse/storage/schema/delta/35/device_stream_id.sql
@@ -0,0 +1,21 @@
+/* Copyright 2016 OpenMarket 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 device_max_stream_id (
+    stream_id BIGINT NOT NULL
+);
+
+INSERT INTO device_max_stream_id (stream_id)
+    SELECT COALESCE(MAX(stream_id), 0) FROM device_inbox;
diff --git a/synapse/storage/schema/delta/35/event_push_actions_index.sql b/synapse/storage/schema/delta/35/event_push_actions_index.sql
new file mode 100644
index 0000000000..2e836d8e9c
--- /dev/null
+++ b/synapse/storage/schema/delta/35/event_push_actions_index.sql
@@ -0,0 +1,17 @@
+/* Copyright 2016 OpenMarket 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.
+ */
+
+ INSERT into background_updates (update_name, progress_json)
+     VALUES ('epa_highlight_index', '{}');
diff --git a/synapse/storage/schema/delta/35/public_room_list_change_stream.sql b/synapse/storage/schema/delta/35/public_room_list_change_stream.sql
new file mode 100644
index 0000000000..dd2bf2e28a
--- /dev/null
+++ b/synapse/storage/schema/delta/35/public_room_list_change_stream.sql
@@ -0,0 +1,33 @@
+/* Copyright 2016 OpenMarket 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 public_room_list_stream (
+    stream_id BIGINT NOT NULL,
+    room_id TEXT NOT NULL,
+    visibility BOOLEAN NOT NULL
+);
+
+INSERT INTO public_room_list_stream (stream_id, room_id, visibility)
+    SELECT 1, room_id, is_public FROM rooms
+    WHERE is_public = CAST(1 AS BOOLEAN);
+
+CREATE INDEX public_room_list_stream_idx on public_room_list_stream(
+    stream_id
+);
+
+CREATE INDEX public_room_list_stream_rm_idx on public_room_list_stream(
+    room_id, stream_id
+);
diff --git a/synapse/storage/schema/delta/35/state.sql b/synapse/storage/schema/delta/35/state.sql
new file mode 100644
index 0000000000..0f1fa68a89
--- /dev/null
+++ b/synapse/storage/schema/delta/35/state.sql
@@ -0,0 +1,22 @@
+/* Copyright 2016 OpenMarket 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 state_group_edges(
+    state_group BIGINT NOT NULL,
+    prev_state_group BIGINT NOT NULL
+);
+
+CREATE INDEX state_group_edges_idx ON state_group_edges(state_group);
+CREATE INDEX state_group_edges_prev_idx ON state_group_edges(prev_state_group);
diff --git a/synapse/storage/schema/delta/35/state_dedupe.sql b/synapse/storage/schema/delta/35/state_dedupe.sql
new file mode 100644
index 0000000000..97e5067ef4
--- /dev/null
+++ b/synapse/storage/schema/delta/35/state_dedupe.sql
@@ -0,0 +1,17 @@
+/* Copyright 2016 OpenMarket 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.
+ */
+
+INSERT into background_updates (update_name, progress_json)
+    VALUES ('state_group_state_deduplication', '{}');
diff --git a/synapse/storage/schema/delta/35/stream_order_to_extrem.sql b/synapse/storage/schema/delta/35/stream_order_to_extrem.sql
new file mode 100644
index 0000000000..2b945d8a57
--- /dev/null
+++ b/synapse/storage/schema/delta/35/stream_order_to_extrem.sql
@@ -0,0 +1,37 @@
+/* Copyright 2016 OpenMarket 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 stream_ordering_to_exterm (
+    stream_ordering BIGINT NOT NULL,
+    room_id TEXT NOT NULL,
+    event_id TEXT NOT NULL
+);
+
+INSERT INTO stream_ordering_to_exterm (stream_ordering, room_id, event_id)
+    SELECT stream_ordering, room_id, event_id FROM event_forward_extremities
+    INNER JOIN (
+        SELECT room_id, max(stream_ordering) as stream_ordering FROM events
+        INNER JOIN event_forward_extremities USING (room_id, event_id)
+        GROUP BY room_id
+    ) AS rms USING (room_id);
+
+CREATE INDEX stream_ordering_to_exterm_idx on stream_ordering_to_exterm(
+    stream_ordering
+);
+
+CREATE INDEX stream_ordering_to_exterm_rm_idx on stream_ordering_to_exterm(
+    room_id, stream_ordering
+);
diff --git a/synapse/storage/state.py b/synapse/storage/state.py
index ec551b0b4f..7eb342674c 100644
--- a/synapse/storage/state.py
+++ b/synapse/storage/state.py
@@ -16,6 +16,7 @@
 from ._base import SQLBaseStore
 from synapse.util.caches.descriptors import cached, cachedList
 from synapse.util.caches import intern_string
+from synapse.storage.engines import PostgresEngine
 
 from twisted.internet import defer
 
@@ -24,6 +25,9 @@ import logging
 logger = logging.getLogger(__name__)
 
 
+MAX_STATE_DELTA_HOPS = 100
+
+
 class StateStore(SQLBaseStore):
     """ Keeps track of the state at a given event.
 
@@ -43,6 +47,20 @@ class StateStore(SQLBaseStore):
       * `state_groups_state`: Maps state group to state events.
     """
 
+    STATE_GROUP_DEDUPLICATION_UPDATE_NAME = "state_group_state_deduplication"
+    STATE_GROUP_INDEX_UPDATE_NAME = "state_group_state_type_index"
+
+    def __init__(self, hs):
+        super(StateStore, self).__init__(hs)
+        self.register_background_update_handler(
+            self.STATE_GROUP_DEDUPLICATION_UPDATE_NAME,
+            self._background_deduplicate_state,
+        )
+        self.register_background_update_handler(
+            self.STATE_GROUP_INDEX_UPDATE_NAME,
+            self._background_index_state,
+        )
+
     @defer.inlineCallbacks
     def get_state_groups_ids(self, room_id, event_ids):
         if not event_ids:
@@ -103,11 +121,8 @@ class StateStore(SQLBaseStore):
             state_groups[event.event_id] = context.state_group
 
             if self._have_persisted_state_group_txn(txn, context.state_group):
-                logger.info("Already persisted state_group: %r", context.state_group)
                 continue
 
-            state_event_ids = dict(context.current_state_ids)
-
             self._simple_insert_txn(
                 txn,
                 table="state_groups",
@@ -118,20 +133,51 @@ class StateStore(SQLBaseStore):
                 },
             )
 
-            self._simple_insert_many_txn(
-                txn,
-                table="state_groups_state",
-                values=[
-                    {
+            # We persist as a delta if we can, while also ensuring the chain
+            # of deltas isn't tooo long, as otherwise read performance degrades.
+            if context.prev_group:
+                potential_hops = self._count_state_group_hops_txn(
+                    txn, context.prev_group
+                )
+            if context.prev_group and potential_hops < MAX_STATE_DELTA_HOPS:
+                self._simple_insert_txn(
+                    txn,
+                    table="state_group_edges",
+                    values={
                         "state_group": context.state_group,
-                        "room_id": event.room_id,
-                        "type": key[0],
-                        "state_key": key[1],
-                        "event_id": state_id,
-                    }
-                    for key, state_id in state_event_ids.items()
-                ],
-            )
+                        "prev_state_group": context.prev_group,
+                    },
+                )
+
+                self._simple_insert_many_txn(
+                    txn,
+                    table="state_groups_state",
+                    values=[
+                        {
+                            "state_group": context.state_group,
+                            "room_id": event.room_id,
+                            "type": key[0],
+                            "state_key": key[1],
+                            "event_id": state_id,
+                        }
+                        for key, state_id in context.delta_ids.items()
+                    ],
+                )
+            else:
+                self._simple_insert_many_txn(
+                    txn,
+                    table="state_groups_state",
+                    values=[
+                        {
+                            "state_group": context.state_group,
+                            "room_id": event.room_id,
+                            "type": key[0],
+                            "state_key": key[1],
+                            "event_id": state_id,
+                        }
+                        for key, state_id in context.current_state_ids.items()
+                    ],
+                )
 
         self._simple_insert_many_txn(
             txn,
@@ -145,6 +191,47 @@ class StateStore(SQLBaseStore):
             ],
         )
 
+    def _count_state_group_hops_txn(self, txn, state_group):
+        """Given a state group, count how many hops there are in the tree.
+
+        This is used to ensure the delta chains don't get too long.
+        """
+        if isinstance(self.database_engine, PostgresEngine):
+            sql = ("""
+                WITH RECURSIVE state(state_group) AS (
+                    VALUES(?::bigint)
+                    UNION ALL
+                    SELECT prev_state_group FROM state_group_edges e, state s
+                    WHERE s.state_group = e.state_group
+                )
+                SELECT count(*) FROM state;
+            """)
+
+            txn.execute(sql, (state_group,))
+            row = txn.fetchone()
+            if row and row[0]:
+                return row[0]
+            else:
+                return 0
+        else:
+            # We don't use WITH RECURSIVE on sqlite3 as there are distributions
+            # that ship with an sqlite3 version that doesn't support it (e.g. wheezy)
+            next_group = state_group
+            count = 0
+
+            while next_group:
+                next_group = self._simple_select_one_onecol_txn(
+                    txn,
+                    table="state_group_edges",
+                    keyvalues={"state_group": next_group},
+                    retcol="prev_state_group",
+                    allow_none=True,
+                )
+                if next_group:
+                    count += 1
+
+            return count
+
     @defer.inlineCallbacks
     def get_current_state(self, room_id, event_type=None, state_key=""):
         if event_type and state_key is not None:
@@ -206,48 +293,124 @@ class StateStore(SQLBaseStore):
     def _get_state_groups_from_groups(self, groups, types):
         """Returns dictionary state_group -> (dict of (type, state_key) -> event id)
         """
-        def f(txn, groups):
-            if types is not None:
-                where_clause = "AND (%s)" % (
-                    " OR ".join(["(type = ? AND state_key = ?)"] * len(types)),
-                )
-            else:
-                where_clause = ""
-
-            sql = (
-                "SELECT state_group, event_id, type, state_key"
-                " FROM state_groups_state WHERE"
-                " state_group IN (%s) %s" % (
-                    ",".join("?" for _ in groups),
-                    where_clause,
-                )
-            )
-
-            args = list(groups)
-            if types is not None:
-                args.extend([i for typ in types for i in typ])
-
-            txn.execute(sql, args)
-            rows = self.cursor_to_dict(txn)
-
-            results = {group: {} for group in groups}
-            for row in rows:
-                key = (row["type"], row["state_key"])
-                results[row["state_group"]][key] = row["event_id"]
-            return results
-
         results = {}
 
         chunks = [groups[i:i + 100] for i in xrange(0, len(groups), 100)]
         for chunk in chunks:
             res = yield self.runInteraction(
                 "_get_state_groups_from_groups",
-                f, chunk
+                self._get_state_groups_from_groups_txn, chunk, types,
             )
             results.update(res)
 
         defer.returnValue(results)
 
+    def _get_state_groups_from_groups_txn(self, txn, groups, types=None):
+        results = {group: {} for group in groups}
+        if isinstance(self.database_engine, PostgresEngine):
+            # Temporarily disable sequential scans in this transaction. This is
+            # a temporary hack until we can add the right indices in
+            txn.execute("SET LOCAL enable_seqscan=off")
+
+            # The below query walks the state_group tree so that the "state"
+            # table includes all state_groups in the tree. It then joins
+            # against `state_groups_state` to fetch the latest state.
+            # It assumes that previous state groups are always numerically
+            # lesser.
+            # The PARTITION is used to get the event_id in the greatest state
+            # group for the given type, state_key.
+            # This may return multiple rows per (type, state_key), but last_value
+            # should be the same.
+            sql = ("""
+                WITH RECURSIVE state(state_group) AS (
+                    VALUES(?::bigint)
+                    UNION ALL
+                    SELECT prev_state_group FROM state_group_edges e, state s
+                    WHERE s.state_group = e.state_group
+                )
+                SELECT type, state_key, last_value(event_id) OVER (
+                    PARTITION BY type, state_key ORDER BY state_group ASC
+                    ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
+                ) AS event_id FROM state_groups_state
+                WHERE state_group IN (
+                    SELECT state_group FROM state
+                )
+                %s
+            """)
+
+            # Turns out that postgres doesn't like doing a list of OR's and
+            # is about 1000x slower, so we just issue a query for each specific
+            # type seperately.
+            if types:
+                clause_to_args = [
+                    (
+                        "AND type = ? AND state_key = ?",
+                        (etype, state_key)
+                    )
+                    for etype, state_key in types
+                ]
+            else:
+                # If types is None we fetch all the state, and so just use an
+                # empty where clause with no extra args.
+                clause_to_args = [("", [])]
+
+            for where_clause, where_args in clause_to_args:
+                for group in groups:
+                    args = [group]
+                    args.extend(where_args)
+
+                    txn.execute(sql % (where_clause,), args)
+                    rows = self.cursor_to_dict(txn)
+                    for row in rows:
+                        key = (row["type"], row["state_key"])
+                        results[group][key] = row["event_id"]
+        else:
+            if types is not None:
+                where_clause = "AND (%s)" % (
+                    " OR ".join(["(type = ? AND state_key = ?)"] * len(types)),
+                )
+            else:
+                where_clause = ""
+
+            # We don't use WITH RECURSIVE on sqlite3 as there are distributions
+            # that ship with an sqlite3 version that doesn't support it (e.g. wheezy)
+            for group in groups:
+                group_tree = [group]
+                next_group = group
+
+                while next_group:
+                    next_group = self._simple_select_one_onecol_txn(
+                        txn,
+                        table="state_group_edges",
+                        keyvalues={"state_group": next_group},
+                        retcol="prev_state_group",
+                        allow_none=True,
+                    )
+                    if next_group:
+                        group_tree.append(next_group)
+
+                sql = ("""
+                    SELECT type, state_key, event_id FROM state_groups_state
+                    INNER JOIN (
+                        SELECT type, state_key, max(state_group) as state_group
+                        FROM state_groups_state
+                        WHERE state_group IN (%s) %s
+                        GROUP BY type, state_key
+                    ) USING (type, state_key, state_group);
+                """) % (",".join("?" for _ in group_tree), where_clause,)
+
+                args = list(group_tree)
+                if types is not None:
+                    args.extend([i for typ in types for i in typ])
+
+                txn.execute(sql, args)
+                rows = self.cursor_to_dict(txn)
+                for row in rows:
+                    key = (row["type"], row["state_key"])
+                    results[group][key] = row["event_id"]
+
+        return results
+
     @defer.inlineCallbacks
     def get_state_for_events(self, event_ids, types):
         """Given a list of event_ids and type tuples, return a list of state
@@ -504,32 +667,184 @@ class StateStore(SQLBaseStore):
 
         defer.returnValue(results)
 
-    def get_all_new_state_groups(self, last_id, current_id, limit):
-        def get_all_new_state_groups_txn(txn):
-            sql = (
-                "SELECT id, room_id, event_id FROM state_groups"
-                " WHERE ? < id AND id <= ? ORDER BY id LIMIT ?"
+    def get_next_state_group(self):
+        return self._state_groups_id_gen.get_next()
+
+    @defer.inlineCallbacks
+    def _background_deduplicate_state(self, progress, batch_size):
+        """This background update will slowly deduplicate state by reencoding
+        them as deltas.
+        """
+        last_state_group = progress.get("last_state_group", 0)
+        rows_inserted = progress.get("rows_inserted", 0)
+        max_group = progress.get("max_group", None)
+
+        BATCH_SIZE_SCALE_FACTOR = 100
+
+        batch_size = max(1, int(batch_size / BATCH_SIZE_SCALE_FACTOR))
+
+        if max_group is None:
+            rows = yield self._execute(
+                "_background_deduplicate_state", None,
+                "SELECT coalesce(max(id), 0) FROM state_groups",
             )
-            txn.execute(sql, (last_id, current_id, limit))
-            groups = txn.fetchall()
+            max_group = rows[0][0]
+
+        def reindex_txn(txn):
+            new_last_state_group = last_state_group
+            for count in xrange(batch_size):
+                txn.execute(
+                    "SELECT id, room_id FROM state_groups"
+                    " WHERE ? < id AND id <= ?"
+                    " ORDER BY id ASC"
+                    " LIMIT 1",
+                    (new_last_state_group, max_group,)
+                )
+                row = txn.fetchone()
+                if row:
+                    state_group, room_id = row
 
-            if not groups:
-                return ([], [])
+                if not row or not state_group:
+                    return True, count
 
-            lower_bound = groups[0][0]
-            upper_bound = groups[-1][0]
-            sql = (
-                "SELECT state_group, type, state_key, event_id"
-                " FROM state_groups_state"
-                " WHERE ? <= state_group AND state_group <= ?"
+                txn.execute(
+                    "SELECT state_group FROM state_group_edges"
+                    " WHERE state_group = ?",
+                    (state_group,)
+                )
+
+                # If we reach a point where we've already started inserting
+                # edges we should stop.
+                if txn.fetchall():
+                    return True, count
+
+                txn.execute(
+                    "SELECT coalesce(max(id), 0) FROM state_groups"
+                    " WHERE id < ? AND room_id = ?",
+                    (state_group, room_id,)
+                )
+                prev_group, = txn.fetchone()
+                new_last_state_group = state_group
+
+                if prev_group:
+                    potential_hops = self._count_state_group_hops_txn(
+                        txn, prev_group
+                    )
+                    if potential_hops >= MAX_STATE_DELTA_HOPS:
+                        # We want to ensure chains are at most this long,#
+                        # otherwise read performance degrades.
+                        continue
+
+                    prev_state = self._get_state_groups_from_groups_txn(
+                        txn, [prev_group], types=None
+                    )
+                    prev_state = prev_state[prev_group]
+
+                    curr_state = self._get_state_groups_from_groups_txn(
+                        txn, [state_group], types=None
+                    )
+                    curr_state = curr_state[state_group]
+
+                    if not set(prev_state.keys()) - set(curr_state.keys()):
+                        # We can only do a delta if the current has a strict super set
+                        # of keys
+
+                        delta_state = {
+                            key: value for key, value in curr_state.items()
+                            if prev_state.get(key, None) != value
+                        }
+
+                        self._simple_delete_txn(
+                            txn,
+                            table="state_group_edges",
+                            keyvalues={
+                                "state_group": state_group,
+                            }
+                        )
+
+                        self._simple_insert_txn(
+                            txn,
+                            table="state_group_edges",
+                            values={
+                                "state_group": state_group,
+                                "prev_state_group": prev_group,
+                            }
+                        )
+
+                        self._simple_delete_txn(
+                            txn,
+                            table="state_groups_state",
+                            keyvalues={
+                                "state_group": state_group,
+                            }
+                        )
+
+                        self._simple_insert_many_txn(
+                            txn,
+                            table="state_groups_state",
+                            values=[
+                                {
+                                    "state_group": state_group,
+                                    "room_id": room_id,
+                                    "type": key[0],
+                                    "state_key": key[1],
+                                    "event_id": state_id,
+                                }
+                                for key, state_id in delta_state.items()
+                            ],
+                        )
+
+            progress = {
+                "last_state_group": state_group,
+                "rows_inserted": rows_inserted + batch_size,
+                "max_group": max_group,
+            }
+
+            self._background_update_progress_txn(
+                txn, self.STATE_GROUP_DEDUPLICATION_UPDATE_NAME, progress
             )
 
-            txn.execute(sql, (lower_bound, upper_bound))
-            state_group_state = txn.fetchall()
-            return (groups, state_group_state)
-        return self.runInteraction(
-            "get_all_new_state_groups", get_all_new_state_groups_txn
+            return False, batch_size
+
+        finished, result = yield self.runInteraction(
+            self.STATE_GROUP_DEDUPLICATION_UPDATE_NAME, reindex_txn
         )
 
-    def get_next_state_group(self):
-        return self._state_groups_id_gen.get_next()
+        if finished:
+            yield self._end_background_update(self.STATE_GROUP_DEDUPLICATION_UPDATE_NAME)
+
+        defer.returnValue(result * BATCH_SIZE_SCALE_FACTOR)
+
+    @defer.inlineCallbacks
+    def _background_index_state(self, progress, batch_size):
+        def reindex_txn(conn):
+            conn.rollback()
+            if isinstance(self.database_engine, PostgresEngine):
+                # postgres insists on autocommit for the index
+                conn.set_session(autocommit=True)
+                try:
+                    txn = conn.cursor()
+                    txn.execute(
+                        "CREATE INDEX CONCURRENTLY state_groups_state_type_idx"
+                        " ON state_groups_state(state_group, type, state_key)"
+                    )
+                    txn.execute(
+                        "DROP INDEX IF EXISTS state_groups_state_id"
+                    )
+                finally:
+                    conn.set_session(autocommit=False)
+            else:
+                txn = conn.cursor()
+                txn.execute(
+                    "CREATE INDEX state_groups_state_type_idx"
+                    " ON state_groups_state(state_group, type, state_key)"
+                )
+                txn.execute(
+                    "DROP INDEX IF EXISTS state_groups_state_id"
+                )
+
+        yield self.runWithConnection(reindex_txn)
+
+        yield self._end_background_update(self.STATE_GROUP_INDEX_UPDATE_NAME)
+
+        defer.returnValue(1)
diff --git a/synapse/storage/stream.py b/synapse/storage/stream.py
index 0577a0525b..07ea969d4d 100644
--- a/synapse/storage/stream.py
+++ b/synapse/storage/stream.py
@@ -531,6 +531,9 @@ class StreamStore(SQLBaseStore):
             )
             defer.returnValue("t%d-%d" % (topo, token))
 
+    def get_room_max_stream_ordering(self):
+        return self._stream_id_gen.get_current_token()
+
     def get_stream_token_for_event(self, event_id):
         """The stream token for an event
         Args: