Change the default value for the `synchronous` pragma from `FULL` to
`NORMAL`.
With this change, SQLite will not aggressively `fsync()` after every
transaction, so there is considerably less disk pressure as disk I/O
can be batched.
See <https://sqlite.org/pragma.html>:
> `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.
Also:
> You lose durability across power lose with synchronous `NORMAL` in `WAL`
> mode, but that is not important for most applications. Transactions
> are still atomic, consistent, and isolated, which are the most
> important characteristics in most use cases.
So, there is no risk of database corruption, and in the extreme
cases of sudden power loss or system crash, some transaction may
roll back.
See also <https://sqlite.org/wal.html>
Co-authored-by: Yorgos Saslis <yorgos.work@proton.me>
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