code-review-dblisted

# Code Review — Database & Persistence Layer Focus on performance, correctness, and safety at the data layer. --- ## Query Correctness - [ ] **N+1 queries** — a loop that loads related records per item. Look for `for item in items: item.related`. Fix with eager loading (`select_related`, `include`, `JOIN`) or a batch fetch outside the loop. - [ ] **Unbounded queries** — `find_all()`, `SELECT *` with no `LIMIT`, `WHERE 1=1`. Every read from a growing table needs pagination or a `LIMIT`. - [ ] **Missing WHERE clause** — an `UPDATE` or `DELETE` with no filter deletes/updates every row. - [ ] **Implicit full-table scan** — a `WHERE` on a column with no index. Check `EXPLAIN` output or migration history. - [ ] **Fetching more columns than needed** — `SELECT *` when only 2 columns are used. Unnecessary data transfer and harder to cache. --- ## Index Strategy - [ ] **Missing index on foreign key** — `FK` columns not in an index cause full scans on JOIN and cascade operations. - [ ] **Missing index on `WHERE`/`ORDER BY` columns** — any column used in a filter, sort, or join should have an index unless the table is tiny (<1k rows). - [ ] **Index on every column** — over-indexing slows writes. Indexes serve reads; add them only for proven query patterns. - [ ] **Composite index column order** — a composite index on (A, B, C) helps queries filtering A, or A+B, but NOT B alone. Confirm the index covers the actual query. - [ ] **Index on high-cardinality boolean** — a boolean colum