From 16c5d95b594e4fe146947c4848057ebe0b9f900b Mon Sep 17 00:00:00 2001
From: David Robertson <davidr@element.io>
Date: Thu, 13 Oct 2022 18:32:16 +0100
Subject: [PATCH] Optimise the event_push_backfill_thread_id bg job (#14172)
Co-authored-by: Erik Johnston <erik@matrix.org>
---
changelog.d/14172.bugfix | 1 +
synapse/storage/databases/main/event_push_actions.py | 10 ++++++++--
2 files changed, 9 insertions(+), 2 deletions(-)
create mode 100644 changelog.d/14172.bugfix
diff --git a/changelog.d/14172.bugfix b/changelog.d/14172.bugfix
new file mode 100644
index 0000000000..36521c670c
--- /dev/null
+++ b/changelog.d/14172.bugfix
@@ -0,0 +1 @@
+Fix poor performance of the `event_push_backfill_thread_id` background update, which was introduced in Synapse 1.68.0rc1.
diff --git a/synapse/storage/databases/main/event_push_actions.py b/synapse/storage/databases/main/event_push_actions.py
index 87d07f7d9b..7f7bcb7094 100644
--- a/synapse/storage/databases/main/event_push_actions.py
+++ b/synapse/storage/databases/main/event_push_actions.py
@@ -297,9 +297,15 @@ class EventPushActionsWorkerStore(ReceiptsWorkerStore, StreamWorkerStore, SQLBas
sql = f"""
UPDATE {table_name}
SET thread_id = 'main'
- WHERE stream_ordering <= ? AND thread_id IS NULL
+ WHERE ? < stream_ordering AND stream_ordering <= ? AND thread_id IS NULL
"""
- txn.execute(sql, (max_stream_ordering,))
+ txn.execute(
+ sql,
+ (
+ start_stream_ordering,
+ max_stream_ordering,
+ ),
+ )
# Update progress.
processed_rows = txn.rowcount
--
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