When synchronous is NORMAL (1), the SQLite database engine will still sync at the most critical moments, but less often than in FULL mode. There is a very small (though non-zero) chance that a power failure at just the wrong time could corrupt the database in journal_mode=DELETE on an older filesystem. WAL mode is safe from corruption with synchronous=NORMAL, and probably DELETE mode is safe too on modern filesystems. WAL mode is always consistent with synchronous=NORMAL, but WAL mode does lose durability. A transaction committed in WAL mode with synchronous=NORMAL might roll back following a power loss or system crash. Transactions are durable across application crashes regardless of the synchronous setting or journal mode. The synchronous=NORMAL setting is a good choice for most applications running in WAL mode.