Issue 62684
What does this MR do?
It adds index on public_emails for users table to speed up query
SELECT ? AS one FROM "users" WHERE "users"."public_email" = ? AND ("users"."id" != ?) LIMIT ?
It could reduce the execution time from 2,480.620 ms to 0.037 ms
before the migration execution plan: https://explain.depesz.com/s/mWii
after the migration execution plan: https://explain.depesz.com/s/cOt6
Database checklist
-
Conforms to the database guides
When adding migrations:
-
Updated db/schema.rb
-
Added a down
method so the migration can be reverted -
Added the output of the migration(s) to the MR body -
Added tests for the migration in spec/migrations
if necessary (e.g. when migrating data)
When adding or modifying queries to improve performance:
-
Included data that shows the performance improvement, preferably in the form of a benchmark -
Included the output of EXPLAIN (ANALYZE, BUFFERS)
of the relevant queries
When adding foreign keys to existing tables:
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Included a migration to remove orphaned rows in the source table before adding the foreign key -
Removed any instances of dependent: ...
that may no longer be necessary
When adding tables:
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Ordered columns based on the Ordering Table Columns guidelines -
Added foreign keys to any columns pointing to data in other tables -
Added indexes for fields that are used in statements such as WHERE, ORDER BY, GROUP BY, and JOINs
When removing columns, tables, indexes or other structures:
-
Removed these in a post-deployment migration -
Made sure the application no longer uses (or ignores) these structures
General checklist
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Changelog entry added, if necessary -
Documentation created/updated -
Tests added for this feature/bug -
Conforms to the code review guidelines -
Conforms to the merge request performance guidelines -
Conforms to the style guides
Edited by yun guo