N+1 Query Problem

When to use

• The user wants to decide between eager loading a relation (with/fetch join), batching IDs into an IN (...), or a single JOIN to collapse N+1 queries.
• The user sees a query-count profiler (Debugbar, Telescope, Clockwork) reporting hundreds of near-identical SELECTs on one request.
• The user loops over a collection of records and accesses a related model inside the loop, firing a separate query for each row.

When NOT to use