Revert "Reintroduce membership tables event stream ordering (#15128)"

This reverts commit e6af49f.

synapse/storage/databases/main/events.py

@@ -1127,15 +1127,11 @@ def _update_current_state_txn(
                 # been inserted into room_memberships.
                 txn.execute_batch(
                     """INSERT INTO current_state_events
-                        (room_id, type, state_key, event_id, membership, event_stream_ordering)
-                    VALUES (
-                        ?, ?, ?, ?,
-                        (SELECT membership FROM room_memberships WHERE event_id = ?),
-                        (SELECT stream_ordering FROM events WHERE event_id = ?)
-                    )
+                        (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, ev_id)
+                        (room_id, key[0], key[1], ev_id, ev_id)
                         for key, ev_id in to_insert.items()
                     ],
                 )
@@ -1162,15 +1158,11 @@ def _update_current_state_txn(
             if to_insert:
                 txn.execute_batch(
                     """INSERT INTO local_current_membership
-                        (room_id, user_id, event_id, membership, event_stream_ordering)
-                    VALUES (
-                        ?, ?, ?,
-                        (SELECT membership FROM room_memberships WHERE event_id = ?),
-                        (SELECT stream_ordering FROM events WHERE event_id = ?)
-                    )
+                        (room_id, user_id, event_id, membership)
+                    VALUES (?, ?, ?, (SELECT membership FROM room_memberships WHERE event_id = ?))
                     """,
                     [
-                        (room_id, key[1], ev_id, ev_id, ev_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])
                     ],
@@ -1776,7 +1768,6 @@ def _store_room_members_txn(
             table="room_memberships",
             keys=(
                 "event_id",
-                "event_stream_ordering",
                 "user_id",
                 "sender",
                 "room_id",
@@ -1787,7 +1778,6 @@ def _store_room_members_txn(
             values=[
                 (
                     event.event_id,
-                    event.internal_metadata.stream_ordering,
                     event.state_key,
                     event.user_id,
                     event.room_id,
@@ -1820,7 +1810,6 @@ def _store_room_members_txn(
                     keyvalues={"room_id": event.room_id, "user_id": event.state_key},
                     values={
                         "event_id": event.event_id,
-                        "event_stream_ordering": event.internal_metadata.stream_ordering,
                         "membership": event.membership,
                     },
                 )

synapse/storage/databases/main/purge_events.py

@@ -428,16 +428,14 @@ def _purge_room_txn(self, txn: LoggingTransaction, room_id: str) -> List[int]:
             "partial_state_events",
             "partial_state_rooms_servers",
             "partial_state_rooms",
-            # Note: the _membership(s) tables have foreign keys to the `events` table
-            # so must be deleted first.
-            "local_current_membership",
-            "room_memberships",
             "events",
             "federation_inbound_events_staging",
+            "local_current_membership",
             "receipts_graph",
             "receipts_linearized",
             "room_aliases",
             "room_depth",
+            "room_memberships",
             "room_stats_state",
             "room_stats_current",
             "room_stats_earliest_token",

synapse/storage/schema/__init__.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-SCHEMA_VERSION = 75  # remember to update the list below when updating
+SCHEMA_VERSION = 74  # remember to update the list below when updating
 """Represents the expectations made by the codebase about the database schema
 
 This should be incremented whenever the codebase changes its requirements on the
@@ -91,19 +91,13 @@
     - A query on `event_stream_ordering` column has now been disambiguated (i.e. the
       codebase can handle the `current_state_events`, `local_current_memberships` and
       `room_memberships` tables having an `event_stream_ordering` column).
-
-Changes in SCHEMA_VERSION = 75:
-    - The `event_stream_ordering` column in membership tables (`current_state_events`,
-      `local_current_membership` & `room_memberships`) is now being populated for new
-      rows. When the background job to populate historical rows lands this will
-      become the compat schema version.
 """
 
 
 SCHEMA_COMPAT_VERSION = (
-    # Queries against `event_stream_ordering` columns in membership tables must
-    # be disambiguated.
-    74
+    # The threads_id column must exist for event_push_actions, event_push_summary,
+    # receipts_linearized, and receipts_graph.
+    73
 )
 """Limit on how far the synapse codebase can be rolled back without breaking db compat