Rename database classes to make some sense (#8033)

1 files changed, 1527 insertions, 0 deletions

diff --git a/synapse/storage/databases/main/events.py b/synapse/storage/databases/main/events.py
new file mode 100644
index 0000000000..4d8a24ce4b
--- /dev/null
+++ b/synapse/storage/databases/main/events.py
@@ -0,0 +1,1527 @@
+# -*- coding: utf-8 -*-
+# Copyright 2014-2016 OpenMarket 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.
+# 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 itertools
+import logging
+from collections import OrderedDict, namedtuple
+from typing import TYPE_CHECKING, Dict, Iterable, List, Tuple
+
+import attr
+from prometheus_client import Counter
+
+from twisted.internet import defer
+
+import synapse.metrics
+from synapse.api.constants import EventContentFields, EventTypes, RelationTypes
+from synapse.api.room_versions import RoomVersions
+from synapse.crypto.event_signing import compute_event_reference_hash
+from synapse.events import EventBase  # noqa: F401
+from synapse.events.snapshot import EventContext  # noqa: F401
+from synapse.logging.utils import log_function
+from synapse.storage._base import db_to_json, make_in_list_sql_clause
+from synapse.storage.database import DatabasePool, LoggingTransaction
+from synapse.storage.databases.main.search import SearchEntry
+from synapse.storage.util.id_generators import StreamIdGenerator
+from synapse.types import StateMap, get_domain_from_id
+from synapse.util.frozenutils import frozendict_json_encoder
+from synapse.util.iterutils import batch_iter
+
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+    from synapse.storage.databases.main import DataStore
+
+
+logger = logging.getLogger(__name__)
+
+persist_event_counter = Counter("synapse_storage_events_persisted_events", "")
+event_counter = Counter(
+    "synapse_storage_events_persisted_events_sep",
+    "",
+    ["type", "origin_type", "origin_entity"],
+)
+
+STATE_EVENT_TYPES_TO_MARK_UNREAD = {
+    EventTypes.Topic,
+    EventTypes.Name,
+    EventTypes.RoomAvatar,
+    EventTypes.Tombstone,
+}
+
+
+def should_count_as_unread(event: EventBase, context: EventContext) -> bool:
+    # Exclude rejected and soft-failed events.
+    if context.rejected or event.internal_metadata.is_soft_failed():
+        return False
+
+    # Exclude notices.
+    if (
+        not event.is_state()
+        and event.type == EventTypes.Message
+        and event.content.get("msgtype") == "m.notice"
+    ):
+        return False
+
+    # Exclude edits.
+    relates_to = event.content.get("m.relates_to", {})
+    if relates_to.get("rel_type") == RelationTypes.REPLACE:
+        return False
+
+    # Mark events that have a non-empty string body as unread.
+    body = event.content.get("body")
+    if isinstance(body, str) and body:
+        return True
+
+    # Mark some state events as unread.
+    if event.is_state() and event.type in STATE_EVENT_TYPES_TO_MARK_UNREAD:
+        return True
+
+    # Mark encrypted events as unread.
+    if not event.is_state() and event.type == EventTypes.Encrypted:
+        return True
+
+    return False
+
+
+def encode_json(json_object):
+    """
+    Encode a Python object as JSON and return it in a Unicode string.
+    """
+    out = frozendict_json_encoder.encode(json_object)
+    if isinstance(out, bytes):
+        out = out.decode("utf8")
+    return out
+
+
+_EventCacheEntry = namedtuple("_EventCacheEntry", ("event", "redacted_event"))
+
+
+@attr.s(slots=True)
+class DeltaState:
+    """Deltas to use to update the `current_state_events` table.
+
+    Attributes:
+        to_delete: List of type/state_keys to delete from current state
+        to_insert: Map of state to upsert into current state
+        no_longer_in_room: The server is not longer in the room, so the room
+            should e.g. be removed from `current_state_events` table.
+    """
+
+    to_delete = attr.ib(type=List[Tuple[str, str]])
+    to_insert = attr.ib(type=StateMap[str])
+    no_longer_in_room = attr.ib(type=bool, default=False)
+
+
+class PersistEventsStore:
+    """Contains all the functions for writing events to the database.
+
+    Should only be instantiated on one process (when using a worker mode setup).
+
+    Note: This is not part of the `DataStore` mixin.
+    """
+
+    def __init__(
+        self, hs: "HomeServer", db: DatabasePool, main_data_store: "DataStore"
+    ):
+        self.hs = hs
+        self.db_pool = db
+        self.store = main_data_store
+        self.database_engine = db.engine
+        self._clock = hs.get_clock()
+
+        self._ephemeral_messages_enabled = hs.config.enable_ephemeral_messages
+        self.is_mine_id = hs.is_mine_id
+
+        # Ideally we'd move these ID gens here, unfortunately some other ID
+        # generators are chained off them so doing so is a bit of a PITA.
+        self._backfill_id_gen = self.store._backfill_id_gen  # type: StreamIdGenerator
+        self._stream_id_gen = self.store._stream_id_gen  # type: StreamIdGenerator
+
+        # This should only exist on instances that are configured to write
+        assert (
+            hs.config.worker.writers.events == hs.get_instance_name()
+        ), "Can only instantiate EventsStore on master"
+
+    @defer.inlineCallbacks
+    def _persist_events_and_state_updates(
+        self,
+        events_and_contexts: List[Tuple[EventBase, EventContext]],
+        current_state_for_room: Dict[str, StateMap[str]],
+        state_delta_for_room: Dict[str, DeltaState],
+        new_forward_extremeties: Dict[str, List[str]],
+        backfilled: bool = False,
+    ):
+        """Persist a set of events alongside updates to the current state and
+        forward extremities tables.
+
+        Args:
+            events_and_contexts:
+            current_state_for_room: Map from room_id to the current state of
+                the room based on forward extremities
+            state_delta_for_room: Map from room_id to the delta to apply to
+                room state
+            new_forward_extremities: Map from room_id to list of event IDs
+                that are the new forward extremities of the room.
+            backfilled
+
+        Returns:
+            Deferred: resolves when the events have been persisted
+        """
+
+        # We want to calculate the stream orderings as late as possible, as
+        # we only notify after all events with a lesser stream ordering have
+        # been persisted. I.e. if we spend 10s inside the with block then
+        # that will delay all subsequent events from being notified about.
+        # Hence why we do it down here rather than wrapping the entire
+        # function.
+        #
+        # Its safe to do this after calculating the state deltas etc as we
+        # only need to protect the *persistence* of the events. This is to
+        # ensure that queries of the form "fetch events since X" don't
+        # return events and stream positions after events that are still in
+        # flight, as otherwise subsequent requests "fetch event since Y"
+        # will not return those events.
+        #
+        # Note: Multiple instances of this function cannot be in flight at
+        # the same time for the same room.
+        if backfilled:
+            stream_ordering_manager = self._backfill_id_gen.get_next_mult(
+                len(events_and_contexts)
+            )
+        else:
+            stream_ordering_manager = self._stream_id_gen.get_next_mult(
+                len(events_and_contexts)
+            )
+
+        with stream_ordering_manager as stream_orderings:
+            for (event, context), stream in zip(events_and_contexts, stream_orderings):
+                event.internal_metadata.stream_ordering = stream
+
+            yield self.db_pool.runInteraction(
+                "persist_events",
+                self._persist_events_txn,
+                events_and_contexts=events_and_contexts,
+                backfilled=backfilled,
+                state_delta_for_room=state_delta_for_room,
+                new_forward_extremeties=new_forward_extremeties,
+            )
+            persist_event_counter.inc(len(events_and_contexts))
+
+            if not backfilled:
+                # backfilled events have negative stream orderings, so we don't
+                # want to set the event_persisted_position to that.
+                synapse.metrics.event_persisted_position.set(
+                    events_and_contexts[-1][0].internal_metadata.stream_ordering
+                )
+
+            for event, context in events_and_contexts:
+                if context.app_service:
+                    origin_type = "local"
+                    origin_entity = context.app_service.id
+                elif self.hs.is_mine_id(event.sender):
+                    origin_type = "local"
+                    origin_entity = "*client*"
+                else:
+                    origin_type = "remote"
+                    origin_entity = get_domain_from_id(event.sender)
+
+                event_counter.labels(event.type, origin_type, origin_entity).inc()
+
+                self.store.get_unread_message_count_for_user.invalidate_many(
+                    (event.room_id,),
+                )
+
+            for room_id, new_state in current_state_for_room.items():
+                self.store.get_current_state_ids.prefill((room_id,), new_state)
+
+            for room_id, latest_event_ids in new_forward_extremeties.items():
+                self.store.get_latest_event_ids_in_room.prefill(
+                    (room_id,), list(latest_event_ids)
+                )
+
+    @defer.inlineCallbacks
+    def _get_events_which_are_prevs(self, event_ids):
+        """Filter the supplied list of event_ids to get those which are prev_events of
+        existing (non-outlier/rejected) events.
+
+        Args:
+            event_ids (Iterable[str]): event ids to filter
+
+        Returns:
+            Deferred[List[str]]: filtered event ids
+        """
+        results = []
+
+        def _get_events_which_are_prevs_txn(txn, batch):
+            sql = """
+            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
+                NOT events.outlier
+                AND rejections.event_id IS NULL
+                AND
+            """
+
+            clause, args = make_in_list_sql_clause(
+                self.database_engine, "prev_event_id", batch
+            )
+
+            txn.execute(sql + clause, args)
+            results.extend(r[0] for r in txn if not db_to_json(r[1]).get("soft_failed"))
+
+        for chunk in batch_iter(event_ids, 100):
+            yield self.db_pool.runInteraction(
+                "_get_events_which_are_prevs", _get_events_which_are_prevs_txn, chunk
+            )
+
+        return 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
+                    NOT events.outlier
+                    AND
+                """
+
+                clause, args = make_in_list_sql_clause(
+                    self.database_engine, "event_id", to_recursively_check
+                )
+
+                txn.execute(sql + clause, args)
+                to_recursively_check = []
+
+                for event_id, prev_event_id, metadata, rejected in txn:
+                    if prev_event_id in existing_prevs:
+                        continue
+
+                    soft_failed = db_to_json(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.db_pool.runInteraction(
+                "_get_prevs_before_rejected", _get_prevs_before_rejected_txn, chunk
+            )
+
+        return existing_prevs
+
+    @log_function
+    def _persist_events_txn(
+        self,
+        txn: LoggingTransaction,
+        events_and_contexts: List[Tuple[EventBase, EventContext]],
+        backfilled: bool,
+        state_delta_for_room: Dict[str, DeltaState] = {},
+        new_forward_extremeties: Dict[str, List[str]] = {},
+    ):
+        """Insert some number of room events into the necessary database tables.
+
+        Rejected events are only inserted into the events table, the events_json table,
+        and the rejections table. Things reading from those table will need to check
+        whether the event was rejected.
+
+        Args:
+            txn
+            events_and_contexts: events to persist
+            backfilled: True if the events were backfilled
+            delete_existing True to purge existing table rows for the events
+                from the database. This is useful when retrying due to
+                IntegrityError.
+            state_delta_for_room: The current-state delta for each room.
+            new_forward_extremetie: The new forward extremities for each room.
+                For each room, a list of the event ids which are the forward
+                extremities.
+
+        """
+        all_events_and_contexts = events_and_contexts
+
+        min_stream_order = events_and_contexts[0][0].internal_metadata.stream_ordering
+        max_stream_order = events_and_contexts[-1][0].internal_metadata.stream_ordering
+
+        self._update_forward_extremities_txn(
+            txn,
+            new_forward_extremities=new_forward_extremeties,
+            max_stream_order=max_stream_order,
+        )
+
+        # Ensure that we don't have the same event twice.
+        events_and_contexts = self._filter_events_and_contexts_for_duplicates(
+            events_and_contexts
+        )
+
+        self._update_room_depths_txn(
+            txn, events_and_contexts=events_and_contexts, backfilled=backfilled
+        )
+
+        # _update_outliers_txn filters out any events which have already been
+        # persisted, and returns the filtered list.
+        events_and_contexts = self._update_outliers_txn(
+            txn, events_and_contexts=events_and_contexts
+        )
+
+        # From this point onwards the events are only events that we haven't
+        # seen before.
+
+        self._store_event_txn(txn, events_and_contexts=events_and_contexts)
+
+        # Insert into event_to_state_groups.
+        self._store_event_state_mappings_txn(txn, events_and_contexts)
+
+        # We want to store event_auth mappings for rejected events, as they're
+        # used in state res v2.
+        # This is only necessary if the rejected event appears in an accepted
+        # event's auth chain, but its easier for now just to store them (and
+        # it doesn't take much storage compared to storing the entire event
+        # anyway).
+        self.db_pool.simple_insert_many_txn(
+            txn,
+            table="event_auth",
+            values=[
+                {
+                    "event_id": event.event_id,
+                    "room_id": event.room_id,
+                    "auth_id": auth_id,
+                }
+                for event, _ in events_and_contexts
+                for auth_id in event.auth_event_ids()
+                if event.is_state()
+            ],
+        )
+
+        # _store_rejected_events_txn filters out any events which were
+        # rejected, and returns the filtered list.
+        events_and_contexts = self._store_rejected_events_txn(
+            txn, events_and_contexts=events_and_contexts
+        )
+
+        # From this point onwards the events are only ones that weren't
+        # rejected.
+
+        self._update_metadata_tables_txn(
+            txn,
+            events_and_contexts=events_and_contexts,
+            all_events_and_contexts=all_events_and_contexts,
+            backfilled=backfilled,
+        )
+
+        # We call this last as it assumes we've inserted the events into
+        # room_memberships, where applicable.
+        self._update_current_state_txn(txn, state_delta_for_room, min_stream_order)
+
+    def _update_current_state_txn(
+        self,
+        txn: LoggingTransaction,
+        state_delta_by_room: Dict[str, DeltaState],
+        stream_id: int,
+    ):
+        for room_id, delta_state in state_delta_by_room.items():
+            to_delete = delta_state.to_delete
+            to_insert = delta_state.to_insert
+
+            if delta_state.no_longer_in_room:
+                # Server is no longer in the room so we delete the room from
+                # current_state_events, being careful we've already updated the
+                # rooms.room_version column (which gets populated in a
+                # background task).
+                self._upsert_room_version_txn(txn, room_id)
+
+                # Before deleting we populate the current_state_delta_stream
+                # so that async background tasks get told what happened.
+                sql = """
+                    INSERT INTO current_state_delta_stream
+                        (stream_id, room_id, type, state_key, event_id, prev_event_id)
+                    SELECT ?, room_id, type, state_key, null, event_id
+                        FROM current_state_events
+                        WHERE room_id = ?
+                """
+                txn.execute(sql, (stream_id, room_id))
+
+                self.db_pool.simple_delete_txn(
+                    txn, table="current_state_events", keyvalues={"room_id": room_id},
+                )
+            else:
+                # We're still in the room, so we update the current state as normal.
+
+                # First we add entries to the current_state_delta_stream. We
+                # do this before updating the current_state_events table so
+                # that we can use it to calculate the `prev_event_id`. (This
+                # allows us to not have to pull out the existing state
+                # unnecessarily).
+                #
+                # The stream_id for the update is chosen to be the minimum of the stream_ids
+                # for the batch of the events that we are persisting; that means we do not
+                # end up in a situation where workers see events before the
+                # current_state_delta updates.
+                #
+                sql = """
+                    INSERT INTO current_state_delta_stream
+                    (stream_id, room_id, type, state_key, event_id, prev_event_id)
+                    SELECT ?, ?, ?, ?, ?, (
+                        SELECT event_id FROM current_state_events
+                        WHERE room_id = ? AND type = ? AND state_key = ?
+                    )
+                """
+                txn.executemany(
+                    sql,
+                    (
+                        (
+                            stream_id,
+                            room_id,
+                            etype,
+                            state_key,
+                            to_insert.get((etype, state_key)),
+                            room_id,
+                            etype,
+                            state_key,
+                        )
+                        for etype, state_key in itertools.chain(to_delete, to_insert)
+                    ),
+                )
+                # Now we actually update the current_state_events table
+
+                txn.executemany(
+                    "DELETE FROM current_state_events"
+                    " WHERE room_id = ? AND type = ? AND state_key = ?",
+                    (
+                        (room_id, etype, state_key)
+                        for etype, state_key in itertools.chain(to_delete, to_insert)
+                    ),
+                )
+
+                # We include the membership in the current state table, hence we do
+                # a lookup when we insert. This assumes that all events have already
+                # been inserted into room_memberships.
+                txn.executemany(
+                    """INSERT INTO current_state_events
+                        (room_id, type, state_key, event_id, membership)
+                    VALUES (?, ?, ?, ?, (SELECT membership FROM room_memberships WHERE event_id = ?))
+                    """,
+                    [
+                        (room_id, key[0], key[1], ev_id, ev_id)
+                        for key, ev_id in to_insert.items()
+                    ],
+                )
+
+            # We now update `local_current_membership`. We do this regardless
+            # of whether we're still in the room or not to handle the case where
+            # e.g. we just got banned (where we need to record that fact here).
+
+            # Note: Do we really want to delete rows here (that we do not
+            # subsequently reinsert below)? While technically correct it means
+            # we have no record of the fact the user *was* a member of the
+            # room but got, say, state reset out of it.
+            if to_delete or to_insert:
+                txn.executemany(
+                    "DELETE FROM local_current_membership"
+                    " WHERE room_id = ? AND user_id = ?",
+                    (
+                        (room_id, state_key)
+                        for etype, state_key in itertools.chain(to_delete, to_insert)
+                        if etype == EventTypes.Member and self.is_mine_id(state_key)
+                    ),
+                )
+
+            if to_insert:
+                txn.executemany(
+                    """INSERT INTO local_current_membership
+                        (room_id, user_id, event_id, membership)
+                    VALUES (?, ?, ?, (SELECT membership FROM room_memberships WHERE event_id = ?))
+                    """,
+                    [
+                        (room_id, key[1], ev_id, ev_id)
+                        for key, ev_id in to_insert.items()
+                        if key[0] == EventTypes.Member and self.is_mine_id(key[1])
+                    ],
+                )
+
+            txn.call_after(
+                self.store._curr_state_delta_stream_cache.entity_has_changed,
+                room_id,
+                stream_id,
+            )
+
+            # Invalidate the various caches
+
+            # Figure out the changes of membership to invalidate the
+            # `get_rooms_for_user` cache.
+            # We find out which membership events we may have deleted
+            # and which we have added, then we invlidate the caches for all
+            # those users.
+            members_changed = {
+                state_key
+                for ev_type, state_key in itertools.chain(to_delete, to_insert)
+                if ev_type == EventTypes.Member
+            }
+
+            for member in members_changed:
+                txn.call_after(
+                    self.store.get_rooms_for_user_with_stream_ordering.invalidate,
+                    (member,),
+                )
+
+            self.store._invalidate_state_caches_and_stream(
+                txn, room_id, members_changed
+            )
+
+    def _upsert_room_version_txn(self, txn: LoggingTransaction, room_id: str):
+        """Update the room version in the database based off current state
+        events.
+
+        This is used when we're about to delete current state and we want to
+        ensure that the `rooms.room_version` column is up to date.
+        """
+
+        sql = """
+            SELECT json FROM event_json
+            INNER JOIN current_state_events USING (room_id, event_id)
+            WHERE room_id = ? AND type = ? AND state_key = ?
+        """
+        txn.execute(sql, (room_id, EventTypes.Create, ""))
+        row = txn.fetchone()
+        if row:
+            event_json = db_to_json(row[0])
+            content = event_json.get("content", {})
+            creator = content.get("creator")
+            room_version_id = content.get("room_version", RoomVersions.V1.identifier)
+
+            self.db_pool.simple_upsert_txn(
+                txn,
+                table="rooms",
+                keyvalues={"room_id": room_id},
+                values={"room_version": room_version_id},
+                insertion_values={"is_public": False, "creator": creator},
+            )
+
+    def _update_forward_extremities_txn(
+        self, txn, new_forward_extremities, max_stream_order
+    ):
+        for room_id, new_extrem in new_forward_extremities.items():
+            self.db_pool.simple_delete_txn(
+                txn, table="event_forward_extremities", keyvalues={"room_id": room_id}
+            )
+            txn.call_after(
+                self.store.get_latest_event_ids_in_room.invalidate, (room_id,)
+            )
+
+        self.db_pool.simple_insert_many_txn(
+            txn,
+            table="event_forward_extremities",
+            values=[
+                {"event_id": ev_id, "room_id": room_id}
+                for room_id, new_extrem in new_forward_extremities.items()
+                for ev_id in new_extrem
+            ],
+        )
+        # 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
+        self.db_pool.simple_insert_many_txn(
+            txn,
+            table="stream_ordering_to_exterm",
+            values=[
+                {
+                    "room_id": room_id,
+                    "event_id": event_id,
+                    "stream_ordering": max_stream_order,
+                }
+                for room_id, new_extrem in new_forward_extremities.items()
+                for event_id in new_extrem
+            ],
+        )
+
+    @classmethod
+    def _filter_events_and_contexts_for_duplicates(cls, events_and_contexts):
+        """Ensure that we don't have the same event twice.
+
+        Pick the earliest non-outlier if there is one, else the earliest one.
+
+        Args:
+            events_and_contexts (list[(EventBase, EventContext)]):
+        Returns:
+            list[(EventBase, EventContext)]: filtered list
+        """
+        new_events_and_contexts = OrderedDict()
+        for event, context in events_and_contexts:
+            prev_event_context = new_events_and_contexts.get(event.event_id)
+            if prev_event_context:
+                if not event.internal_metadata.is_outlier():
+                    if prev_event_context[0].internal_metadata.is_outlier():
+                        # To ensure correct ordering we pop, as OrderedDict is
+                        # ordered by first insertion.
+                        new_events_and_contexts.pop(event.event_id, None)
+                        new_events_and_contexts[event.event_id] = (event, context)
+            else:
+                new_events_and_contexts[event.event_id] = (event, context)
+        return list(new_events_and_contexts.values())
+
+    def _update_room_depths_txn(self, txn, events_and_contexts, backfilled):
+        """Update min_depth for each room
+
+        Args:
+            txn (twisted.enterprise.adbapi.Connection): db connection
+            events_and_contexts (list[(EventBase, EventContext)]): events
+                we are persisting
+            backfilled (bool): True if the events were backfilled
+        """
+        depth_updates = {}
+        for event, context in events_and_contexts:
+            # Remove the any existing cache entries for the event_ids
+            txn.call_after(self.store._invalidate_get_event_cache, event.event_id)
+            if not backfilled:
+                txn.call_after(
+                    self.store._events_stream_cache.entity_has_changed,
+                    event.room_id,
+                    event.internal_metadata.stream_ordering,
+                )
+
+            if not event.internal_metadata.is_outlier() and not context.rejected:
+                depth_updates[event.room_id] = max(
+                    event.depth, depth_updates.get(event.room_id, event.depth)
+                )
+
+        for room_id, depth in depth_updates.items():
+            self._update_min_depth_for_room_txn(txn, room_id, depth)
+
+    def _update_outliers_txn(self, txn, events_and_contexts):
+        """Update any outliers with new event info.
+
+        This turns outliers into ex-outliers (unless the new event was
+        rejected).
+
+        Args:
+            txn (twisted.enterprise.adbapi.Connection): db connection
+            events_and_contexts (list[(EventBase, EventContext)]): events
+                we are persisting
+
+        Returns:
+            list[(EventBase, EventContext)] new list, without events which
+            are already in the events table.
+        """
+        txn.execute(
+            "SELECT event_id, outlier FROM events WHERE event_id in (%s)"
+            % (",".join(["?"] * len(events_and_contexts)),),
+            [event.event_id for event, _ in events_and_contexts],
+        )
+
+        have_persisted = {event_id: outlier for event_id, outlier in txn}
+
+        to_remove = set()
+        for event, context in events_and_contexts:
+            if event.event_id not in have_persisted:
+                continue
+
+            to_remove.add(event)
+
+            if context.rejected:
+                # If the event is rejected then we don't care if the event
+                # was an outlier or not.
+                continue
+
+            outlier_persisted = have_persisted[event.event_id]
+            if not event.internal_metadata.is_outlier() and outlier_persisted:
+                # We received a copy of an event that we had already stored as
+                # an outlier in the database. We now have some state at that
+                # so we need to update the state_groups table with that state.
+
+                # insert into event_to_state_groups.
+                try:
+                    self._store_event_state_mappings_txn(txn, ((event, context),))
+                except Exception:
+                    logger.exception("")
+                    raise
+
+                metadata_json = encode_json(event.internal_metadata.get_dict())
+
+                sql = "UPDATE event_json SET internal_metadata = ? WHERE event_id = ?"
+                txn.execute(sql, (metadata_json, event.event_id))
+
+                # Add an entry to the ex_outlier_stream table to replicate the
+                # change in outlier status to our workers.
+                stream_order = event.internal_metadata.stream_ordering
+                state_group_id = context.state_group
+                self.db_pool.simple_insert_txn(
+                    txn,
+                    table="ex_outlier_stream",
+                    values={
+                        "event_stream_ordering": stream_order,
+                        "event_id": event.event_id,
+                        "state_group": state_group_id,
+                    },
+                )
+
+                sql = "UPDATE events SET outlier = ? WHERE event_id = ?"
+                txn.execute(sql, (False, event.event_id))
+
+                # Update the event_backward_extremities table now that this
+                # event isn't an outlier any more.
+                self._update_backward_extremeties(txn, [event])
+
+        return [ec for ec in events_and_contexts if ec[0] not in to_remove]
+
+    def _store_event_txn(self, txn, events_and_contexts):
+        """Insert new events into the event and event_json tables
+
+        Args:
+            txn (twisted.enterprise.adbapi.Connection): db connection
+            events_and_contexts (list[(EventBase, EventContext)]): events
+                we are persisting
+        """
+
+        if not events_and_contexts:
+            # nothing to do here
+            return
+
+        def event_dict(event):
+            d = event.get_dict()
+            d.pop("redacted", None)
+            d.pop("redacted_because", None)
+            return d
+
+        self.db_pool.simple_insert_many_txn(
+            txn,
+            table="event_json",
+            values=[
+                {
+                    "event_id": event.event_id,
+                    "room_id": event.room_id,
+                    "internal_metadata": encode_json(
+                        event.internal_metadata.get_dict()
+                    ),
+                    "json": encode_json(event_dict(event)),
+                    "format_version": event.format_version,
+                }
+                for event, _ in events_and_contexts
+            ],
+        )
+
+        self.db_pool.simple_insert_many_txn(
+            txn,
+            table="events",
+            values=[
+                {
+                    "stream_ordering": event.internal_metadata.stream_ordering,
+                    "topological_ordering": event.depth,
+                    "depth": event.depth,
+                    "event_id": event.event_id,
+                    "room_id": event.room_id,
+                    "type": event.type,
+                    "processed": True,
+                    "outlier": event.internal_metadata.is_outlier(),
+                    "origin_server_ts": int(event.origin_server_ts),
+                    "received_ts": self._clock.time_msec(),
+                    "sender": event.sender,
+                    "contains_url": (
+                        "url" in event.content and isinstance(event.content["url"], str)
+                    ),
+                    "count_as_unread": should_count_as_unread(event, context),
+                }
+                for event, context in events_and_contexts
+            ],
+        )
+
+        for event, _ in events_and_contexts:
+            if not event.internal_metadata.is_redacted():
+                # If we're persisting an unredacted event we go and ensure
+                # that we mark any redactions that reference this event as
+                # requiring censoring.
+                self.db_pool.simple_update_txn(
+                    txn,
+                    table="redactions",
+                    keyvalues={"redacts": event.event_id},
+                    updatevalues={"have_censored": False},
+                )
+
+    def _store_rejected_events_txn(self, txn, events_and_contexts):
+        """Add rows to the 'rejections' table for received events which were
+        rejected
+
+        Args:
+            txn (twisted.enterprise.adbapi.Connection): db connection
+            events_and_contexts (list[(EventBase, EventContext)]): events
+                we are persisting
+
+        Returns:
+            list[(EventBase, EventContext)] new list, without the rejected
+                events.
+        """
+        # Remove the rejected events from the list now that we've added them
+        # to the events table and the events_json table.
+        to_remove = set()
+        for event, context in events_and_contexts:
+            if context.rejected:
+                # Insert the event_id into the rejections table
+                self._store_rejections_txn(txn, event.event_id, context.rejected)
+                to_remove.add(event)
+
+        return [ec for ec in events_and_contexts if ec[0] not in to_remove]
+
+    def _update_metadata_tables_txn(
+        self, txn, events_and_contexts, all_events_and_contexts, backfilled
+    ):
+        """Update all the miscellaneous tables for new events
+
+        Args:
+            txn (twisted.enterprise.adbapi.Connection): db connection
+            events_and_contexts (list[(EventBase, EventContext)]): events
+                we are persisting
+            all_events_and_contexts (list[(EventBase, EventContext)]): all
+                events that we were going to persist. This includes events
+                we've already persisted, etc, that wouldn't appear in
+                events_and_context.
+            backfilled (bool): True if the events were backfilled
+        """
+
+        # Insert all the push actions into the event_push_actions table.
+        self._set_push_actions_for_event_and_users_txn(
+            txn,
+            events_and_contexts=events_and_contexts,
+            all_events_and_contexts=all_events_and_contexts,
+        )
+
+        if not events_and_contexts:
+            # nothing to do here
+            return
+
+        for event, context in events_and_contexts:
+            if event.type == EventTypes.Redaction and event.redacts is not None:
+                # Remove the entries in the event_push_actions table for the
+                # redacted event.
+                self._remove_push_actions_for_event_id_txn(
+                    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(
+            txn, events=[event for event, _ in events_and_contexts]
+        )
+
+        for event, _ in events_and_contexts:
+            if event.type == EventTypes.Name:
+                # Insert into the event_search table.
+                self._store_room_name_txn(txn, event)
+            elif event.type == EventTypes.Topic:
+                # Insert into the event_search table.
+                self._store_room_topic_txn(txn, event)
+            elif event.type == EventTypes.Message:
+                # Insert into the event_search table.
+                self._store_room_message_txn(txn, event)
+            elif event.type == EventTypes.Redaction and event.redacts is not None:
+                # Insert into the redactions table.
+                self._store_redaction(txn, event)
+            elif event.type == EventTypes.Retention:
+                # Update the room_retention table.
+                self._store_retention_policy_for_room_txn(txn, event)
+
+            self._handle_event_relations(txn, event)
+
+            # Store the labels for this event.
+            labels = event.content.get(EventContentFields.LABELS)
+            if labels:
+                self.insert_labels_for_event_txn(
+                    txn, event.event_id, labels, event.room_id, event.depth
+                )
+
+            if self._ephemeral_messages_enabled:
+                # If there's an expiry timestamp on the event, store it.
+                expiry_ts = event.content.get(EventContentFields.SELF_DESTRUCT_AFTER)
+                if isinstance(expiry_ts, int) and not event.is_state():
+                    self._insert_event_expiry_txn(txn, event.event_id, expiry_ts)
+
+        # Insert into the room_memberships table.
+        self._store_room_members_txn(
+            txn,
+            [
+                event
+                for event, _ in events_and_contexts
+                if event.type == EventTypes.Member
+            ],
+            backfilled=backfilled,
+        )
+
+        # Insert event_reference_hashes table.
+        self._store_event_reference_hashes_txn(
+            txn, [event for event, _ in events_and_contexts]
+        )
+
+        state_events_and_contexts = [
+            ec for ec in events_and_contexts if ec[0].is_state()
+        ]
+
+        state_values = []
+        for event, context in state_events_and_contexts:
+            vals = {
+                "event_id": event.event_id,
+                "room_id": event.room_id,
+                "type": event.type,
+                "state_key": event.state_key,
+            }
+
+            # TODO: How does this work with backfilling?
+            if hasattr(event, "replaces_state"):
+                vals["prev_state"] = event.replaces_state
+
+            state_values.append(vals)
+
+        self.db_pool.simple_insert_many_txn(
+            txn, table="state_events", values=state_values
+        )
+
+        # Prefill the event cache
+        self._add_to_cache(txn, events_and_contexts)
+
+    def _add_to_cache(self, txn, events_and_contexts):
+        to_prefill = []
+
+        rows = []
+        N = 200
+        for i in range(0, len(events_and_contexts), N):
+            ev_map = {e[0].event_id: e[0] for e in events_and_contexts[i : i + N]}
+            if not ev_map:
+                break
+
+            sql = (
+                "SELECT "
+                " e.event_id as event_id, "
+                " r.redacts as redacts,"
+                " rej.event_id as rejects "
+                " FROM events as e"
+                " LEFT JOIN rejections as rej USING (event_id)"
+                " LEFT JOIN redactions as r ON e.event_id = r.redacts"
+                " WHERE "
+            )
+
+            clause, args = make_in_list_sql_clause(
+                self.database_engine, "e.event_id", list(ev_map)
+            )
+
+            txn.execute(sql + clause, args)
+            rows = self.db_pool.cursor_to_dict(txn)
+            for row in rows:
+                event = ev_map[row["event_id"]]
+                if not row["rejects"] and not row["redacts"]:
+                    to_prefill.append(
+                        _EventCacheEntry(event=event, redacted_event=None)
+                    )
+
+        def prefill():
+            for cache_entry in to_prefill:
+                self.store._get_event_cache.prefill(
+                    (cache_entry[0].event_id,), cache_entry
+                )
+
+        txn.call_after(prefill)
+
+    def _store_redaction(self, txn, event):
+        # invalidate the cache for the redacted event
+        txn.call_after(self.store._invalidate_get_event_cache, event.redacts)
+
+        self.db_pool.simple_insert_txn(
+            txn,
+            table="redactions",
+            values={
+                "event_id": event.event_id,
+                "redacts": event.redacts,
+                "received_ts": self._clock.time_msec(),
+            },
+        )
+
+    def insert_labels_for_event_txn(
+        self, txn, event_id, labels, room_id, topological_ordering
+    ):
+        """Store the mapping between an event's ID and its labels, with one row per
+        (event_id, label) tuple.
+
+        Args:
+            txn (LoggingTransaction): The transaction to execute.
+            event_id (str): The event's ID.
+            labels (list[str]): A list of text labels.
+            room_id (str): The ID of the room the event was sent to.
+            topological_ordering (int): The position of the event in the room's topology.
+        """
+        return self.db_pool.simple_insert_many_txn(
+            txn=txn,
+            table="event_labels",
+            values=[
+                {
+                    "event_id": event_id,
+                    "label": label,
+                    "room_id": room_id,
+                    "topological_ordering": topological_ordering,
+                }
+                for label in labels
+            ],
+        )
+
+    def _insert_event_expiry_txn(self, txn, event_id, expiry_ts):
+        """Save the expiry timestamp associated with a given event ID.
+
+        Args:
+            txn (LoggingTransaction): The database transaction to use.
+            event_id (str): The event ID the expiry timestamp is associated with.
+            expiry_ts (int): The timestamp at which to expire (delete) the event.
+        """
+        return self.db_pool.simple_insert_txn(
+            txn=txn,
+            table="event_expiry",
+            values={"event_id": event_id, "expiry_ts": expiry_ts},
+        )
+
+    def _store_event_reference_hashes_txn(self, txn, events):
+        """Store a hash for a PDU
+        Args:
+            txn (cursor):
+            events (list): list of Events.
+        """
+
+        vals = []
+        for event in events:
+            ref_alg, ref_hash_bytes = compute_event_reference_hash(event)
+            vals.append(
+                {
+                    "event_id": event.event_id,
+                    "algorithm": ref_alg,
+                    "hash": memoryview(ref_hash_bytes),
+                }
+            )
+
+        self.db_pool.simple_insert_many_txn(
+            txn, table="event_reference_hashes", values=vals
+        )
+
+    def _store_room_members_txn(self, txn, events, backfilled):
+        """Store a room member in the database.
+        """
+        self.db_pool.simple_insert_many_txn(
+            txn,
+            table="room_memberships",
+            values=[
+                {
+                    "event_id": event.event_id,
+                    "user_id": event.state_key,
+                    "sender": event.user_id,
+                    "room_id": event.room_id,
+                    "membership": event.membership,
+                    "display_name": event.content.get("displayname", None),
+                    "avatar_url": event.content.get("avatar_url", None),
+                }
+                for event in events
+            ],
+        )
+
+        for event in events:
+            txn.call_after(
+                self.store._membership_stream_cache.entity_has_changed,
+                event.state_key,
+                event.internal_metadata.stream_ordering,
+            )
+            txn.call_after(
+                self.store.get_invited_rooms_for_local_user.invalidate,
+                (event.state_key,),
+            )
+
+            # We update the local_current_membership table only if the event is
+            # "current", i.e., its something that has just happened.
+            #
+            # This will usually get updated by the `current_state_events` handling,
+            # unless its an outlier, and an outlier is only "current" if it's an "out of
+            # band membership", like a remote invite or a rejection of a remote invite.
+            if (
+                self.is_mine_id(event.state_key)
+                and not backfilled
+                and event.internal_metadata.is_outlier()
+                and event.internal_metadata.is_out_of_band_membership()
+            ):
+                self.db_pool.simple_upsert_txn(
+                    txn,
+                    table="local_current_membership",
+                    keyvalues={"room_id": event.room_id, "user_id": event.state_key},
+                    values={
+                        "event_id": event.event_id,
+                        "membership": event.membership,
+                    },
+                )
+
+    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.db_pool.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.store.get_relations_for_event.invalidate_many, (parent_id,))
+        txn.call_after(
+            self.store.get_aggregation_groups_for_event.invalidate_many, (parent_id,)
+        )
+
+        if rel_type == RelationTypes.REPLACE:
+            txn.call_after(self.store.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.db_pool.simple_delete_txn(
+            txn, table="event_relations", keyvalues={"event_id": redacted_event_id}
+        )
+
+    def _store_room_topic_txn(self, txn, event):
+        if hasattr(event, "content") and "topic" in event.content:
+            self.store_event_search_txn(
+                txn, event, "content.topic", event.content["topic"]
+            )
+
+    def _store_room_name_txn(self, txn, event):
+        if hasattr(event, "content") and "name" in event.content:
+            self.store_event_search_txn(
+                txn, event, "content.name", event.content["name"]
+            )
+
+    def _store_room_message_txn(self, txn, event):
+        if hasattr(event, "content") and "body" in event.content:
+            self.store_event_search_txn(
+                txn, event, "content.body", event.content["body"]
+            )
+
+    def _store_retention_policy_for_room_txn(self, txn, event):
+        if hasattr(event, "content") and (
+            "min_lifetime" in event.content or "max_lifetime" in event.content
+        ):
+            if (
+                "min_lifetime" in event.content
+                and not isinstance(event.content.get("min_lifetime"), int)
+            ) or (
+                "max_lifetime" in event.content
+                and not isinstance(event.content.get("max_lifetime"), int)
+            ):
+                # Ignore the event if one of the value isn't an integer.
+                return
+
+            self.db_pool.simple_insert_txn(
+                txn=txn,
+                table="room_retention",
+                values={
+                    "room_id": event.room_id,
+                    "event_id": event.event_id,
+                    "min_lifetime": event.content.get("min_lifetime"),
+                    "max_lifetime": event.content.get("max_lifetime"),
+                },
+            )
+
+            self.store._invalidate_cache_and_stream(
+                txn, self.store.get_retention_policy_for_room, (event.room_id,)
+            )
+
+    def store_event_search_txn(self, txn, event, key, value):
+        """Add event to the search table
+
+        Args:
+            txn (cursor):
+            event (EventBase):
+            key (str):
+            value (str):
+        """
+        self.store.store_search_entries_txn(
+            txn,
+            (
+                SearchEntry(
+                    key=key,
+                    value=value,
+                    event_id=event.event_id,
+                    room_id=event.room_id,
+                    stream_ordering=event.internal_metadata.stream_ordering,
+                    origin_server_ts=event.origin_server_ts,
+                ),
+            ),
+        )
+
+    def _set_push_actions_for_event_and_users_txn(
+        self, txn, events_and_contexts, all_events_and_contexts
+    ):
+        """Handles moving push actions from staging table to main
+        event_push_actions table for all events in `events_and_contexts`.
+
+        Also ensures that all events in `all_events_and_contexts` are removed
+        from the push action staging area.
+
+        Args:
+            events_and_contexts (list[(EventBase, EventContext)]): events
+                we are persisting
+            all_events_and_contexts (list[(EventBase, EventContext)]): all
+                events that we were going to persist. This includes events
+                we've already persisted, etc, that wouldn't appear in
+                events_and_context.
+        """
+
+        sql = """
+            INSERT INTO event_push_actions (
+                room_id, event_id, user_id, actions, stream_ordering,
+                topological_ordering, notif, highlight
+            )
+            SELECT ?, event_id, user_id, actions, ?, ?, notif, highlight
+            FROM event_push_actions_staging
+            WHERE event_id = ?
+        """
+
+        if events_and_contexts:
+            txn.executemany(
+                sql,
+                (
+                    (
+                        event.room_id,
+                        event.internal_metadata.stream_ordering,
+                        event.depth,
+                        event.event_id,
+                    )
+                    for event, _ in events_and_contexts
+                ),
+            )
+
+        for event, _ in events_and_contexts:
+            user_ids = self.db_pool.simple_select_onecol_txn(
+                txn,
+                table="event_push_actions_staging",
+                keyvalues={"event_id": event.event_id},
+                retcol="user_id",
+            )
+
+            for uid in user_ids:
+                txn.call_after(
+                    self.store.get_unread_event_push_actions_by_room_for_user.invalidate_many,
+                    (event.room_id, uid),
+                )
+
+        # Now we delete the staging area for *all* events that were being
+        # persisted.
+        txn.executemany(
+            "DELETE FROM event_push_actions_staging WHERE event_id = ?",
+            ((event.event_id,) for event, _ in all_events_and_contexts),
+        )
+
+    def _remove_push_actions_for_event_id_txn(self, txn, room_id, event_id):
+        # Sad that we have to blow away the cache for the whole room here
+        txn.call_after(
+            self.store.get_unread_event_push_actions_by_room_for_user.invalidate_many,
+            (room_id,),
+        )
+        txn.execute(
+            "DELETE FROM event_push_actions WHERE room_id = ? AND event_id = ?",
+            (room_id, event_id),
+        )
+
+    def _store_rejections_txn(self, txn, event_id, reason):
+        self.db_pool.simple_insert_txn(
+            txn,
+            table="rejections",
+            values={
+                "event_id": event_id,
+                "reason": reason,
+                "last_check": self._clock.time_msec(),
+            },
+        )
+
+    def _store_event_state_mappings_txn(
+        self, txn, events_and_contexts: Iterable[Tuple[EventBase, EventContext]]
+    ):
+        state_groups = {}
+        for event, context in events_and_contexts:
+            if event.internal_metadata.is_outlier():
+                continue
+
+            # if the event was rejected, just give it the same state as its
+            # predecessor.
+            if context.rejected:
+                state_groups[event.event_id] = context.state_group_before_event
+                continue
+
+            state_groups[event.event_id] = context.state_group
+
+        self.db_pool.simple_insert_many_txn(
+            txn,
+            table="event_to_state_groups",
+            values=[
+                {"state_group": state_group_id, "event_id": event_id}
+                for event_id, state_group_id in state_groups.items()
+            ],
+        )
+
+        for event_id, state_group_id in state_groups.items():
+            txn.call_after(
+                self.store._get_state_group_for_event.prefill,
+                (event_id,),
+                state_group_id,
+            )
+
+    def _update_min_depth_for_room_txn(self, txn, room_id, depth):
+        min_depth = self.store._get_min_depth_interaction(txn, room_id)
+
+        if min_depth is not None and depth >= min_depth:
+            return
+
+        self.db_pool.simple_upsert_txn(
+            txn,
+            table="room_depth",
+            keyvalues={"room_id": room_id},
+            values={"min_depth": depth},
+        )
+
+    def _handle_mult_prev_events(self, txn, events):
+        """
+        For the given event, update the event edges table and forward and
+        backward extremities tables.
+        """
+        self.db_pool.simple_insert_many_txn(
+            txn,
+            table="event_edges",
+            values=[
+                {
+                    "event_id": ev.event_id,
+                    "prev_event_id": e_id,
+                    "room_id": ev.room_id,
+                    "is_state": False,
+                }
+                for ev in events
+                for e_id in ev.prev_event_ids()
+            ],
+        )
+
+        self._update_backward_extremeties(txn, events)
+
+    def _update_backward_extremeties(self, txn, events):
+        """Updates the event_backward_extremities tables based on the new/updated
+        events being persisted.
+
+        This is called for new events *and* for events that were outliers, but
+        are now being persisted as non-outliers.
+
+        Forward extremities are handled when we first start persisting the events.
+        """
+        events_by_room = {}
+        for ev in events:
+            events_by_room.setdefault(ev.room_id, []).append(ev)
+
+        query = (
+            "INSERT INTO event_backward_extremities (event_id, room_id)"
+            " SELECT ?, ? WHERE NOT EXISTS ("
+            " SELECT 1 FROM event_backward_extremities"
+            " WHERE event_id = ? AND room_id = ?"
+            " )"
+            " AND NOT EXISTS ("
+            " SELECT 1 FROM events WHERE event_id = ? AND room_id = ? "
+            " AND outlier = ?"
+            " )"
+        )
+
+        txn.executemany(
+            query,
+            [
+                (e_id, ev.room_id, e_id, ev.room_id, e_id, ev.room_id, False)
+                for ev in events
+                for e_id in ev.prev_event_ids()
+                if not ev.internal_metadata.is_outlier()
+            ],
+        )
+
+        query = (
+            "DELETE FROM event_backward_extremities"
+            " WHERE event_id = ? AND room_id = ?"
+        )
+        txn.executemany(
+            query,
+            [
+                (ev.event_id, ev.room_id)
+                for ev in events
+                if not ev.internal_metadata.is_outlier()
+            ],
+        )