vetkit.data-access.query-in-loop
A database query runs inside a loop, once per item (the N+1 query pattern). The number of round trips grows with the data, so code that is fast on a development database becomes slow and holds connections for longer once real tables and lists grow.
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Suite: Production readiness
javascript, typescript
A database query runs inside a loop, once per item (the N+1 query pattern). The number of round trips grows with the data, so code that is fast on a development database becomes slow and holds connections for longer once real tables and lists grow.
Category: DATABASE · Engine rule severity: WARNING
How to fix it
Load what the loop needs with one query before it (for example findMany({ where: { id: { in: ids } } }), Drizzle inArray(...), Supabase .in('id', ids), a join or an include) and look rows up in a Map inside the loop. Batch writes with the bulk API (createMany, insert(...).values([...]), insertMany, bulkCreate, an array upsert) or a single deleteMany / DELETE … WHERE id IN (…).
References
Source: packages/engine/rules/data-access/javascript.yml.
python
A database query runs inside a loop, once per item (the N+1 query pattern). The number of round trips grows with the data, so code that is fast on a development database becomes slow and holds connections for longer once real tables and lists grow.
Category: DATABASE · Engine rule severity: WARNING
How to fix it
Load the rows before the loop (Django filter(id__in=ids) / in_bulk, select_related / prefetch_related for relations; SQLAlchemy where(Model.id.in_(ids)), selectinload / joinedload) and look them up in a dict inside it. Batch writes with bulk_create / bulk_update, executemany, insert_many or one UPDATE … WHERE id IN (…), and commit once after the loop.
References
Source: packages/engine/rules/data-access/python.yml.
ruby
A database query runs inside a loop, once per item (the N+1 query pattern). The number of round trips grows with the data, so code that is fast on a development database becomes slow and holds connections for longer once real tables and lists grow.
Category: DATABASE · Engine rule severity: WARNING
How to fix it
Load the records before the loop (Model.where(id: ids).index_by(&:id), includes / preload for associations) and look them up inside it. Insert rows with one insert_all / upsert_all instead of a create per item.
References
Source: packages/engine/rules/data-access/ruby.yml.
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