Snapshot

During recovery, Sophia tries to read disk indexes. To reduce recovery time for big databases, Sophia periodically writes index dump to the disk generating a single snapshot file. This operation is called Snapshot.

Only indexes are saved during the operation, but database records remain untouched.

Snapshot period interval can be set or disabled using compaction.zone.snapshot_period variable.

/* take snapshot every 10 minutes */
sp_setint(env, "compaction.0.snapshot_period", 360);

Another important purpose of Snapshot is saving necessary statistic to distinct Hot and Cold node files used by Anti-Cache storage mode.