2 files changed, 6 insertions, 0 deletions
diff --git a/changelog.d/16455.bugfix b/changelog.d/16455.bugfix
new file mode 100644
index 0000000000..653a25d3b6
--- /dev/null
+++ b/changelog.d/16455.bugfix
@@ -0,0 +1 @@
+Prevent the purging of large rooms from timing out when Postgres is in use. The timeout which causes this issue was introduced in Synapse 1.88.0.
diff --git a/synapse/storage/databases/main/purge_events.py b/synapse/storage/databases/main/purge_events.py
index dea0e0458c..1e11bf2706 100644
--- a/synapse/storage/databases/main/purge_events.py
+++ b/synapse/storage/databases/main/purge_events.py
@@ -89,6 +89,11 @@ class PurgeEventsStore(StateGroupWorkerStore, CacheInvalidationWorkerStore):
         # furthermore, we might already have the table from a previous (failed)
         # purge attempt, so let's drop the table first.
 
+        if isinstance(self.database_engine, PostgresEngine):
+            # Disable statement timeouts for this transaction; purging rooms can
+            # take a while!
+            txn.execute("SET LOCAL statement_timeout = 0")
+
         txn.execute("DROP TABLE IF EXISTS events_to_purge")
 
         txn.execute(