Optimize database query for last deployment
What does this MR do?
This MR fixes the query statement timeout issue on Environment#last_deployment
.
Currently, the executed query looks like this:
SELECT
"deployments".*
FROM
"deployments"
WHERE
"deployments"."environment_id" = 693272
AND "deployments"."status" = 2
ORDER BY
deployments.id DESC
LIMIT
1;
which produces the following query plan on db-lab:
Limit (cost=0.57..3.38 rows=1 width=139) (actual time=64952.563..64952.566 rows=1 loops=1)
Buffers: shared hit=1789 read=70646 dirtied=482
I/O Timings: read=64229.280
-> Index Scan using index_deployments_on_environment_id_and_id on public.deployments (cost=0.57..109970.76 rows=39200 width=139) (actual time=64952.560..64952.561 rows=1 loops=1)
Index Cond: (deployments.environment_id = 693272)
Filter: (deployments.status = 2)
Rows Removed by Filter: 72178
Buffers: shared hit=1789 read=70646 dirtied=482
I/O Timings: read=64229.280
It seems index_deployments_on_environment_id_status_and_finished_at
is not used. Probably because it's sorted by deployments.id
.
In this MR, we'll introduce a new index on (environment_id, status, id)
. With this index, the query plan will look like:
Limit (cost=0.57..1.68 rows=1 width=139) (actual time=0.664..0.665 rows=1 loops=1)
Buffers: shared hit=4 read=4
I/O Timings: read=0.522
-> Index Scan using dosuken_test on public.deployments (cost=0.57..43722.10 rows=39304 width=139) (actual time=0.658..0.658 rows=1 loops=1)
Index Cond: ((deployments.environment_id = 693272) AND (deployments.status = 2))
Buffers: shared hit=4 read=4
I/O Timings: read=0.522
It's fast enough with cold cacche.
Migration
INFO: This script is a predefined script in devkitkat.
== 20210331145548 AddIndexForLastDeployment: reverting ========================
-- transaction_open?()
-> 0.0000s
-- indexes(:deployments)
-> 0.0089s
-- remove_index(:deployments, {:algorithm=>:concurrently, :name=>"index_deployments_on_environment_id_status_and_id"})
-> 0.0047s
== 20210331145548 AddIndexForLastDeployment: reverted (0.0144s) ===============
== 20210331145548 AddIndexForLastDeployment: migrating ========================
-- transaction_open?()
-> 0.0000s
-- index_exists?(:deployments, [:environment_id, :status, :id], {:name=>"index_deployments_on_environment_id_status_and_id", :algorithm=>:concurrently})
-> 0.0059s
-- add_index(:deployments, [:environment_id, :status, :id], {:name=>"index_deployments_on_environment_id_status_and_id", :algorithm=>:concurrently})
-> 0.0083s
== 20210331145548 AddIndexForLastDeployment: migrated (0.0152s) ===============
Closes #325552 (closed)
Does this MR meet the acceptance criteria?
Conformity
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Edited by Mayra Cabrera