Backfill + reactive prefetch can re-drill the same category multiple
times, and the parts insert path had no dedupe guard. Result: 8.2%
duplicate rows on pl24, 14.5% on parts-catalogs, and 33.7% on emex —
~108k extra rows across 7,571 categories on 224 vehicles. Every drilled
catalog page rendered each part twice (the Tampon example: 32 rows for
19 distinct OEMs).
* Migration 0010 — phase 1 deletes existing dupes preserving the
oldest row per (vehicle_id, category_id, oem_code, name, position)
group; phase 2 adds a UNIQUE INDEX over the same tuple with NULLS NOT
DISTINCT (PG 15+) so null position/vehicle_id collapse like equal
values rather than each counting as its own "distinct" row. Idempotent
CREATE UNIQUE INDEX IF NOT EXISTS so the runner is safe to re-apply.
* All five insert(parts).values(...).returning() call sites
(parts.service, categories.service ×3, catalog.service) get
.onConflictDoNothing() so future re-drills no-op instead of erroring
on the new constraint. `.returning()` continues to surface only the
newly-inserted rows; existing logs read `Stored N parts` as actual
net insertions, which is what we want.
Dry-run on dev DB: 524,540 → 425,186 parts (99,354 dupes deleted), index
created cleanly. Same delta expected on prod (~108k drop).
drizzle-orm 0.41 doesn't expose .nullsNotDistinct() on the index builder
so the constraint is owned by raw SQL — see the inline comment in the
parts schema and the migration file. Future schema generators should NOT
try to drop or rewrite this index.
