ttCkptConfig

Description

Changes the configuration of the background checkpointer dynamically or returns the currently active settings of the configuration parameters. Changes made using ttCkptConfig become effective immediately. Thus, changes to ckptRate can take effect on a checkpoint that is currently in progress.

Changes made to the background checkpointer using ttCkptConfig are persistent. Subsequent loads of the data store retain the new settings, unless the CkptFrequency and CkptLogVolume connection attributes are specified in the DSN or connection string, in which case the attribute values are used instead.

Required privilege

This procedure requires no privilege to query the current values. It requires the ADMIN privilege to change the current values.

Syntax

ttCkptConfig(ckptFrequency, ckptLogVolume, ckptRate)

Parameters

ttCkptConfig has these parameters:

Parameter	Type	Description
`ckptFrequency`	TT_INTEGER	Checkpoint frequency in seconds. Values from 0 to MAXINT are allowed. A value of 0 means that checkpoint frequency is not considered when scheduling checkpoints.
`ckptLogVolume`	TT_INTEGER	Log volume between checkpoints in megabytes. Values from 0 to MAXINT are allowed. A value of 0 means that checkpoint log volume is not considered when scheduling checkpoints.
`ckptRate`	TT_INTEGER	Specifies the rate in MB per second at which a checkpoint should be written to disk. A value of 0 indicates that the rate should not be limited, a value of NULL means that the rate should be left unchanged. Changes to this parameter take effect even on a checkpoint that is currently in-progress.

Result set

ttCkptConfig returns these results:

Column	Type	Description
`ckptFrequency`	TT_INTEGER NOT NULL	Currently active setting for checkpoint frequency in seconds.
`ckptLogVolume`	TT_INTEGER NOT NULL	Currently active setting for log volume between checkpoints in Megabytes.
`ckptRate`	TT_INTEGER NOT NULL	Current rate at which checkpoints are written to disk.

Examples

To view the current settings of the background checkpointer configuration parameters, use:

CALL ttCkptConfig;
< 600, 32, 0 >
1 row found.

To stop the background checkpointer from initiating checkpoints unless the log reaches its limit, use:

CALL ttCkptConfig(0);
< 0, 32, 0 >
1 row found.

To stop the background checkpointer from initiating checkpoints, use:

CALL ttCkptConfig(NULL, 0);
< 0, 0, 0 >
1 row found.

To set the background checkpointer configuration to initiate a checkpoint every 600 seconds or to checkpoint when the log reaches 32 megabytes (whichever comes first), use:

CALL ttCkptConfig(600, 32);
< 600, 32, 0 >
1 row found.

Notes

By default, TimesTen performs background checkpoints at regular intervals.

In the case that your application attempts to perform a checkpoint operation while a backup is in process, the backup waits until the checkpoint finishes. Regardless of whether the checkpoint is a background checkpoint or an application-requested checkpoint, the behavior is:

If a backup or checkpoint is running and you try to do a backup, it will wait for the running backup or checkpoint to finish.
If a backup or checkpoint is running and you try to do a checkpoint, it will not wait. It will return an error right away.

To turn off background checkpointing, set CkptFrequency=0 and CkptLogVolume=0.