https://sonarly.com/issue/16678?type=bug
The `timelineActivity` table lacks database indexes on foreign key columns created for custom object morph relations, causing a 3,491ms sequential scan when loading a single custom object record's timeline activities.
Fix: **What changed:** When creating a custom object, Twenty automatically creates default relations to standard objects like `timelineActivity`, `noteTarget`, `taskTarget`, `attachment`, and `favorite`. The function `generateMorphOrRelationFlatFieldMetadataPair` already generates both the relation field metadata AND a BTREE index on the FK join column for the MANY_TO_ONE side. However, in `buildDefaultRelationFlatFieldMetadatasForCustomObject`, the destructuring `const { flatFieldMetadatas } = generateMorphOrRelationFlatFieldMetadataPair(...)` was silently discarding the `indexMetadatas` return value.
**The fix** (2 files, ~10 lines changed):
1. **`build-default-relation-flat-field-metadatas-for-custom-object.util.ts`**: Added `standardRelationIndexMetadatas` to the accumulator record type. Now destructures `indexMetadatas` alongside `flatFieldMetadatas` and accumulates them across all default relation objects.
2. **`from-create-object-input-to-flat-object-metadata-and-flat-field-metadatas-to-create.util.ts`**: Spreads the new `standardRelationIndexMetadatas` into `flatIndexMetadataToCreate` alongside the existing search vector GIN index.
**Why this is the right fix:** The index generation logic was already correct in `generateMorphOrRelationFlatFieldMetadataPair` (used successfully for user-created relation fields). The bug was purely that the custom object creation pipeline discarded the generated indexes. This was explicitly noted as a TODO in commit `fbd3286792` ("Index v2 side effects"): *"Will handle morph indexes in a new dedicated PR."*
**Note for existing workspaces:** This fix only affects NEW custom object creation. Existing workspaces with custom objects will still have missing indexes on their standard object tables. A one-time migration or `workspace:sync-metadata` run would be needed to backfill those indexes for existing custom objects.
Sonarly Claude Code
a8d37db19c