Combine project timestamps updates into a single statement
What does this MR do and why?
We currently have these Event
callbacks:
after_create :reset_project_activity
after_create :set_last_repository_updated_at, if: :push_action?
Each one may produce separate UPDATE statements.
Old statements
-- reset_project_activity
UPDATE
"projects"
SET
"updated_at" = $ 1,
"last_activity_at" = $ 2
WHERE
"projects"."id" = $ 3
AND (last_activity_at <= $ 4)
-- set_last_repository_updated_at
UPDATE
"projects"
SET
"updated_at" = $ 1,
"last_repository_updated_at" = $ 2
WHERE
"projects"."id" = $ 3
AND (
last_repository_updated_at < $ 4
OR last_repository_updated_at IS NULL
)
These two statements are one of the top contributors to WAL generated for projects
table.
This MR combines them into a single statement, so that the write amplification cost is paid only once.
New combined statement
UPDATE
"projects"
SET
"updated_at" = '2024-06-25 22:16:40.944515',
-- In case we are doing an update we can as well update both timestamps
"last_activity_at" = '2024-06-25 22:16:40.944515',
"last_repository_updated_at" = '2024-06-25 22:16:40.944515'
WHERE
"projects"."id" = 333
-- Execute the update only if one of these conditions is met
AND (
last_activity_at <= '2024-06-25 21:16:40.947778'
OR last_repository_updated_at < '2024-06-25 22:11:40.948814'
OR last_repository_updated_at IS NULL
)
https://console.postgres.ai/gitlab/gitlab-production-main/sessions/29492/commands/91625
This query can change and include just one of the timestamps if the other was recently updated, for example
- update only
last_activity_at
- update only
last_repository_updated_at
This change is behind the combined_project_update_on_event_creation
feature flag.
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