COMMITINTERVAL

The COMMITINTERVAL configuration parameter identifies how often changes are committed to IBM® MQ for a subscription. Each subscription commits changes independently.

Description

At each interval, the capture service issues an MQCMIT call. This call signals the MQ queue manager to make messages that were placed on send queues available to the user applications.

Changes for a subscription are committed at COMMITINTERVAL frequencies when the interval expires and all changes for the UOR that is currently being processed are written to MQ.

Finding the best commit interval is a compromise between latency (the delay between the time that transactions are originally committed at the source and finally committed to MQ) and the CPU overhead that is associated with the commit process:

To reduce latency, shorten the commit interval.
Transactions will be pushed through with less delay. Reduced latency is especially important if changes are used to trigger events.
To reduce CPU overhead, lengthen the commit interval.
A longer commit interval lets you send as many database transactions as possible for each MQ transaction. If you lengthen the commit interval, you might be limited by the maximum queue depth (number of messages) for send queues and by the queue manager's maximum uncommitted messages (MAXUMSGS) attribute. If a capture service waits longer between commits, the publication of some transactions might be delayed, which could increase latency.

Specifications

Use: Configuration parameter for the capture service.

Service class: CAP

Service task name: CECCAP

Data type: TIME

Default: 500 MS

Valid values:

The COMMITINTERVAL may be set to a value between 1 millisecond and 1 hour. You can specify the value in the following form:

nMS: n milliseconds
nS: n seconds
nM: n minutes
nH: n hours