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CHECKPOINT Statement

The CHECKPOINT statement synchronizes data in the write-ahead log (WAL) to the database data file. For in-memory databases this statement will succeed with no effect.

Examples

Synchronize data in the default database:

CHECKPOINT;

Synchronize data in the specified database:

CHECKPOINT file_db;

Abort any in-progress transactions to synchronize the data:

FORCE CHECKPOINT;

Syntax

Checkpoint operations happen automatically based on the WAL size (see Configuration). This statement is for manual checkpoint actions.

Behavior

The default CHECKPOINT command will fail if there are any running transactions. Including FORCE will abort any transactions and execute the checkpoint operation.

Also see the related PRAGMA option for further behavior modification.

Reclaiming Space

When performing a checkpoint (automatic or otherwise), the space occupied by deleted rows is partially reclaimed. Note that this does not remove all deleted rows, but rather merges row groups that have a significant amount of deletes together. In the current implementation this requires ~25% of rows to be deleted in adjacent row groups.

When running in in-memory mode, checkpointing has no effect, hence it does not reclaim space after deletes in in-memory databases.

Warning The VACUUM statement does not trigger vacuuming deletes and hence does not reclaim space.

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