# 22. Virtuoso Functions Guide - checkpoint_interval

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## checkpoint_interval

Configure database checkpointing
integer checkpoint_interval (in minutes integer);
Parameters
minutes – integer number of minutes between checkpoints.
Return Types

Previous value of CheckpointInterval in the configuration file as an integer.

Description

This function changes the database checkpointing interval to the given value in minutes. It may also be used to disable checkpointing in two ways: By setting checkpoint interval to 0, the checkpoint will only be performed after roll forward upon database startup. A setting of -1 will disable all checkpointing. Main use for this function is to ensure a clean online backup of the database slices. Copying of the database may take long and checkpointing would modify those files in mid-copy, thus rendering the resulting copy unusable. In case the system should, for some reason or another, become unstable, it is sometimes better to disable checkpointing after a database restart to resume backing up from where it was left prior to a system crash. Disabling all checkpointing by giving checkpoint_interval the value of -1 will do just that.

The interval setting will be saved in the server configuration file as value of CheckpointInterval in section [Parameters], thus it will persist over consecutive server shutdown/restart cycles. A long checkpoint_interval setting will produce longer transaction logs, which in turn prolongs the time it takes for the database to perform a roll forward upon restart in case it was shut down without making a checkpoint.

Errors

Parameter data type checking errors

Examples
Simple examples

Disable checkpoints:

    SQL> checkpoint_interval(-1);

    Done. -- 25 msec.

Re-enable checkpoints (every 2 hrs):

    SQL> checkpoint_interval(120);
    callret
    VARCHAR
    ______________________________________________________

    -1

    Done. -- 4 msec.

See Also

backup

CheckpointInterval setting in Configuring Server Startup Files section