The Python driver is buggy-by-default. This has been documented in recent versions [1], and is kinda sane for the undo log, but not so good if you want to use s

The Python driver is buggy-by-default. This has been documented in recent versions [1], and is kinda sane for the undo log, but not so good if you want to use snapshot isolation. I guess many bindings would make the same decision. Basically they delay the emission of BEGIN until the first DML/DDL is executed. If you fix this (which is easy), then WAL works just fine. Note that transactions, as is standard, span from BEGIN/COMMIT to COMMIT/ROLLBACK. See e.g. https://docs.sqlalchemy.org/en/latest/dialects/sqlite.html#transaction-isolation-level https://docs.sqlalchemy.org/en/latest/dialects/sqlite.html#t... and https://docs.sqlalchemy.org/en/latest/dialects/sqlite.html#pysqlite-serializable https://docs.sqlalchemy.org/en/latest/dialects/sqlite.html#p... [1] Really it's more like "encoded": https://docs.python.org/3/library/sqlite3.html#controlling-transactions https://docs.python.org/3/library/sqlite3.html#controlling-t... -- you already need to know the issue to understand that this section specifies the root cause.