CKPTINTVL

onconfig.std
value

300

units

Seconds

range of values

Any value greater than or equal to 30

takes effect

When shared memory is initialized

utilities

onutil

refer to

The following material:

• Checkpoints in the shared-memory and fast-recovery chapters of the IBM Informix: Administrator's Guide
• Your IBM Informix: Performance Guide

CKPTINTVL specifies the frequency, expressed in seconds, at which the database server checks to determine whether a checkpoint is needed. When a full checkpoint occurs, all pages in the shared-memory buffer pool are written to disk. When a fuzzy checkpoint occurs, nonfuzzy pages are written to disk, and the page numbers of fuzzy pages are recorded in the logical log.

If you set CKPTINTVL to an interval that is too short, the system spends too much time performing checkpoints, and the performance of other work suffers. If you set CKPTINTVL to an interval that is too long, fast recovery might take too long.

In practice, 30 seconds is the smallest interval that the database server checks. However, other conditions, such as the physical log becoming 75 percent full, also cause the database server to perform checkpoints. Therefore, the actual interval between some checkpoints can be less than 30 seconds.

To modify the CKPTINTVL parameter dynamically, use the onutil SET command. Example:

% onutil
1> SET CKPTINTVL 500;