From df366966b4f16d22330f1a3783a6e4bee8aa22a7 Mon Sep 17 00:00:00 2001 From: Erik Johnston Date: Wed, 29 Nov 2023 11:54:42 +0000 Subject: [PATCH] Speed up pruning of `user_ips` table (#16667) Silly query planner --- changelog.d/16667.misc | 1 + synapse/storage/databases/main/client_ips.py | 17 +++++++---------- 2 files changed, 8 insertions(+), 10 deletions(-) create mode 100644 changelog.d/16667.misc diff --git a/changelog.d/16667.misc b/changelog.d/16667.misc new file mode 100644 index 000000000..51aeca924 --- /dev/null +++ b/changelog.d/16667.misc @@ -0,0 +1 @@ +Reduce database load of pruning old `user_ips`. diff --git a/synapse/storage/databases/main/client_ips.py b/synapse/storage/databases/main/client_ips.py index d4b14aaeb..1df773105 100644 --- a/synapse/storage/databases/main/client_ips.py +++ b/synapse/storage/databases/main/client_ips.py @@ -465,18 +465,15 @@ class ClientIpWorkerStore(ClientIpBackgroundUpdateStore, MonthlyActiveUsersWorke # # This works by finding the max last_seen that is less than the given # time, but has no more than N rows before it, deleting all rows with - # a lesser last_seen time. (We COALESCE so that the sub-SELECT always - # returns exactly one row). + # a lesser last_seen time. (We use an `IN` clause to force postgres to + # use the index, otherwise it tends to do a seq scan). sql = """ DELETE FROM user_ips - WHERE last_seen <= ( - SELECT COALESCE(MAX(last_seen), -1) - FROM ( - SELECT last_seen FROM user_ips - WHERE last_seen <= ? - ORDER BY last_seen ASC - LIMIT 5000 - ) AS u + WHERE last_seen IN ( + SELECT last_seen FROM user_ips + WHERE last_seen <= ? + ORDER BY last_seen ASC + LIMIT 5000 ) """