database

Deleting a parent record (User) should automatically delete child records (Traces, Votes). Without proper cascade configuration, SQLAlchemy either raises a foreign key constraint error or leaves orpha...

Need to run Alembic migrations that work on both PostgreSQL and SQLite. SQLite doesn't support ALTER TABLE for column renames or type changes, causing migration failures in test environments.

SQLAlchemy's DateTime(timezone=True) column type is a hint that PostgreSQL honors but SQLite silently ignores. Values stored via datetime.now(UTC) are persisted without timezone info in SQLite and ret...

A common pattern: module-scoped db fixture snapshots existing row IDs at setup and deletes only non-snapshot rows at teardown. Two failure modes: (a) rows seeded by a now-removed init path persist ind...

When SQLAlchemy/SQLModel creates a table with an sa.Enum(...) column against PostgreSQL, the database auto-creates a backing named type (e.g. `passwordresetstatus`). op.drop_table removes the table bu...

Adding a new audit-snapshot column (one whose value should record what was true at link/observation time, e.g. an OAuth identity's verified tenant domain, an order's currency at purchase) to a table t...