Improve performance of recent Ci::Runner scope
What does this MR do and why?
Describe in detail what your merge request does and why.
This MR optimizes the query behind the recent
Ci::Runner
scope so that it uses UNION ALL
instead of OR
. This allows making use of the index_ci_runners_on_id_desc_and_contacted_at_desc
and index_ci_runners_on_created_at_and_id_desc
indices.
Screenshots or screen recordings
Screenshots are required for UI changes, and strongly recommended for all other merge requests.
How to set up and validate locally
Numbered steps to set up and validate the change are strongly suggested.
Database queries
Ci::Runner.recent
Previous query
SQL query
SELECT "ci_runners".*
FROM "ci_runners"
WHERE (ci_runners.created_at >= '2022-10-09 13:40:10.667767'
OR ci_runners.contacted_at >= '2022-10-09 13:40:10.667767')
Query execution plan
https://postgres.ai/console/gitlab/gitlab-production-ci/sessions/14307/commands/50173
Seq Scan on public.ci_runners (cost=0.00..660129.96 rows=557228 width=282) (actual time=0.029..3331.239 rows=396589 loops=1)
Filter: ((ci_runners.created_at >= '2022-10-09 13:40:10.667767'::timestamp without time zone) OR (ci_runners.contacted_at >= '2022-10-09 13:40:10.667767'::timestamp without time zone))
Rows Removed by Filter: 1434475
Buffers: shared hit=134303 read=23863 dirtied=2 written=2
I/O Timings: read=2249.003 write=0.109
New query
SQL query
SELECT "ci_runners".*
FROM ((
SELECT "ci_runners".*
FROM "ci_runners"
WHERE "ci_runners"."created_at" >= '2022-10-09 14:25:11.733405')
UNION ALL (
SELECT "ci_runners".*
FROM "ci_runners"
WHERE "ci_runners"."contacted_at" >= '2022-10-09 14:25:11.733492')) ci_runners
Query execution plan
https://postgres.ai/console/gitlab/gitlab-production-ci/sessions/14307/commands/50191
Append (cost=0.43..467231.24 rows=602903 width=282) (actual time=0.074..1132.169 rows=604613 loops=1)
Buffers: shared hit=623268
I/O Timings: read=0.000 write=0.000
-> Index Scan using index_ci_runners_on_created_at_and_id_desc on public.ci_runners (cost=0.43..208649.26 rows=216817 width=282) (actual time=0.073..489.829 rows=217893 loops=1)
Index Cond: (ci_runners.created_at >= '2022-10-09 14:25:11.733405'::timestamp without time zone)
Buffers: shared hit=229799
I/O Timings: read=0.000 write=0.000
-> Index Scan using index_ci_runners_on_contacted_at_desc_and_id_desc on public.ci_runners ci_runners_1 (cost=0.43..249538.44 rows=386086 width=282) (actual time=0.026..585.561 rows=386720 loops=1)
Index Cond: (ci_runners_1.contacted_at >= '2022-10-09 14:25:11.733492'::timestamp without time zone)
Buffers: shared hit=393469
I/O Timings: read=0.000 write=0.000
MR acceptance checklist
This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.
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I have evaluated the MR acceptance checklist for this MR.