Fix background update table-scanning `events` (#14374)
When this background update did its last batch, it would try to update all the
events that had been inserted since the bgupdate started, which could cause a
table-scan. Make sure we limit the update correctly.
2 files changed, 9 insertions, 8 deletions
diff --git a/changelog.d/14374.bugfix b/changelog.d/14374.bugfix
new file mode 100644
index 0000000000..8366cfbf8a
--- /dev/null
+++ b/changelog.d/14374.bugfix
@@ -0,0 +1 @@
+Fix a background database update, introduced in Synapse 1.64.0, which could cause poor database performance.
diff --git a/synapse/storage/databases/main/events_bg_updates.py b/synapse/storage/databases/main/events_bg_updates.py
index 6e8aeed7b4..9e31798ab1 100644
--- a/synapse/storage/databases/main/events_bg_updates.py
+++ b/synapse/storage/databases/main/events_bg_updates.py
@@ -1435,16 +1435,16 @@ class EventsBackgroundUpdatesStore(SQLBaseStore):
),
)
- endpoint = None
row = txn.fetchone()
if row:
endpoint = row[0]
+ else:
+ # if the query didn't return a row, we must be almost done. We just
+ # need to go up to the recorded max_stream_ordering.
+ endpoint = max_stream_ordering_inclusive
- where_clause = "stream_ordering > ?"
- args = [min_stream_ordering_exclusive]
- if endpoint:
- where_clause += " AND stream_ordering <= ?"
- args.append(endpoint)
+ where_clause = "stream_ordering > ? AND stream_ordering <= ?"
+ args = [min_stream_ordering_exclusive, endpoint]
# now do the updates.
txn.execute(
@@ -1458,13 +1458,13 @@ class EventsBackgroundUpdatesStore(SQLBaseStore):
)
logger.info(
- "populated new `events` columns up to %s/%i: updated %i rows",
+ "populated new `events` columns up to %i/%i: updated %i rows",
endpoint,
max_stream_ordering_inclusive,
txn.rowcount,
)
- if endpoint is None:
+ if endpoint >= max_stream_ordering_inclusive:
# we're done
return True
|
