Add indexes to improve join table performance#6645
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Poor performance has been noted when deleting records, particularly in the bulk-remove parents flow and when bulk-deleting vaccination records. A likely cause is that some join tables are only indexed in one direction, which can make deletion queries slower. Jira-Issue: MAV-6735
thomasleese
approved these changes
Apr 20, 2026
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Poor performance has been noted when deleting records in Mavis, particularly in:
A likely cause is that some join tables are only indexed in one direction. That means queries which delete or clean up rows via the associated record side of the join can be slower than necessary.
This change adds reverse indexes for the join tables involved in those deletion paths.
These are the delete paths in the job:
manage-vaccinations-in-schools/app/jobs/bulk_remove_parent_relationships_job.rb
Line 42 in 92fa6b8
manage-vaccinations-in-schools/app/jobs/bulk_remove_parent_relationships_job.rb
Line 45 in 92fa6b8
The reverse index on
immunisation_imports_vaccination_recordsshould improve performance when deleting vaccination records linked to immunisation imports, by making it faster to locate and remove the related join-table rows. This is relevant to the bulk cleanup work discussed in MAV-2997.Jira Issue - MAV-6735