diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index 91462495ab..6610549281 100644
--- a/synapse/storage/events.py
+++ b/synapse/storage/events.py
@@ -1425,7 +1425,7 @@ class EventsStore(SQLBaseStore):
# We calculate the new entries for the backward extremeties by finding
# all events that point to events that are to be purged
txn.execute(
- "SELECT e.event_id FROM events as e"
+ "SELECT DISTINCT e.event_id FROM events as e"
" INNER JOIN event_edges as ed ON e.event_id = ed.prev_event_id"
" INNER JOIN events as e2 ON e2.event_id = ed.event_id"
" WHERE e.room_id = ? AND e.topological_ordering < ?"
@@ -1434,6 +1434,20 @@ class EventsStore(SQLBaseStore):
)
new_backwards_extrems = txn.fetchall()
+ txn.execute(
+ "DELETE FROM event_backward_extremities WHERE room_id = ?",
+ (room_id,)
+ )
+
+ # Update backward extremeties
+ txn.executemany(
+ "INSERT INTO event_backward_extremities (room_id, event_id)"
+ " VALUES (?, ?)",
+ [
+ (room_id, event_id) for event_id, in new_backwards_extrems
+ ]
+ )
+
# Get all state groups that are only referenced by events that are
# to be deleted.
txn.execute(
@@ -1486,20 +1500,12 @@ class EventsStore(SQLBaseStore):
"event_search",
"event_signatures",
"rejections",
- "event_backward_extremities",
):
txn.executemany(
"DELETE FROM %s WHERE event_id = ?" % (table,),
to_delete
)
- # Update backward extremeties
- txn.executemany(
- "INSERT INTO event_backward_extremities (room_id, event_id)"
- " VALUES (?, ?)",
- [(room_id, event_id) for event_id, in new_backwards_extrems]
- )
-
txn.executemany(
"DELETE FROM events WHERE event_id = ?",
to_delete
|
