fix:ActiveRecord::QueryCanceled #5921

[shubham-021]

Fixes #5921

Describe the changes you have made in this PR -

Application was facing this issue : PG::QueryCanceled: ERROR: canceling statement due to statement timeout

This issue was coming from CircuitVerse/app/controllers/projects_controller.rb line 31 that is
"if current_visit && !Ahoy::Event.exists?(visit_id: current_visit.id, name: "Visited project #{@project.id}")"

The query was slow because the ahoy_events table was missing an index on the combination of visit_id and name , which led PostgreSQL to scan the entire database resulting in timeout.

I added a database index on the ahoy_events table for the columns visit_id and name, using a non-blocking migration which improves query performance

Screenshots of the UI changes (If any) -

Checklist before requesting a review

• I have added proper PR title and linked to the issue
• I have performed a self-review of my code
• If it is a core feature, I have added thorough tests.

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Summary by CodeRabbit

• Chores
  • Improved database performance by adding a new index to the ahoy_events table for the visit_id and name columns.

[coderabbitai]

Walkthrough

A new Rails migration is introduced to add a concurrent composite index on the visit_id and name columns of the ahoy_events table. The schema file is updated to reflect this new index and the latest schema version. No other changes are present.

Changes

Cohort / File(s)	Change Summary
Migration: Add composite index db/migrate/20250730084559_add_index_to_ahoy_events_on_visit_id_and_name.rb	Adds a migration to create a concurrent index on ahoy_events(visit_id, name); disables DDL transaction wrapping.
Schema update db/schema.rb	Updates schema version and adds the new composite index on ahoy_events.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~7 minutes

Assessment against linked issues

Objective	Addressed	Explanation
Add a concurrent composite index on ahoy_events(visit_id, name) to address query timeouts (#5921)	✅

Assessment against linked issues: Out-of-scope changes

No out-of-scope changes found.

Possibly related issues

• ActiveRecord::QueryCanceled: [safely] PG::QueryCanceled: ERROR: canceling statement due to statement timeout (ActiveRecord::QueryCanceled) #5922: Also requests a concurrent index on ahoy_events(visit_id, name) for performance.
• ActiveRecord::QueryCanceled: PG::QueryCanceled: ERROR: canceling statement due to statement timeout (ActiveRecord::QueryCanceled) #5920: Describes the same query timeout issue and solution via composite index.
• ActiveRecord::QueryCanceled: [safely] PG::QueryCanceled: ERROR: canceling statement due to statement timeout (ActiveRecord::QueryCanceled) #5924: Seeks to improve query performance on ahoy_events using the same index.

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📜 Recent review details

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Review profile: CHILL
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📥 Commits

Reviewing files that changed from the base of the PR and between 4662ff9 and f0e01f7.

⛔ Files ignored due to path filters (1)

• Gemfile.lock is excluded by !**/*.lock

📒 Files selected for processing (2)

• db/migrate/20250730084559_add_index_to_ahoy_events_on_visit_id_and_name.rb (1 hunks)
• db/schema.rb (2 hunks)

🔇 Additional comments (3)

db/migrate/20250730084559_add_index_to_ahoy_events_on_visit_id_and_name.rb (1)

1-7: Excellent migration implementation!

This migration correctly addresses the query timeout issue by:

• Using disable_ddl_transaction! to allow concurrent index creation
• Adding a composite index on [:visit_id, :name] that matches the problematic query pattern
• Using algorithm: :concurrently to prevent table locks during deployment

The column order is optimal since visit_id is the primary filter in the original query.

db/schema.rb (2)

13-13: Schema version updated correctly.

The version timestamp matches the migration file and follows Rails conventions.

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53-53: Index added correctly to schema.

The composite index index_ahoy_events_on_visit_id_and_name is properly defined and positioned within the ahoy_events table. This will significantly improve the performance of the query that was causing timeouts.

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