The Q Capture program parameters that you can tune for performance are the commit_interval, memory_limit, and sleep_interval parameters. You can also set the max_message_size, monitor_interval, and pruning_interval parameters.
The following figure illustrates how these Q Capture parameters help control the program's interaction with Db2® and WebSphere® MQ.
Figure 1. Important tuning parameters for the Q Capture program: 1. sleep_interval; 2. memory_limit; 3. commit_interval. This figure shows how some of the Q Capture program's activities are controlled by operating parameters that you can tune: 1. Q Capture reads the Db2 log for changes to subscribed tables. When there are no new changes, the program "sleeps" for a period of time set by sleep_interval. 2. In memory, Q Capture uses the log records to reassemble transactions, and then creates messages to convey the transactions. The amount of memory that the program can use for this processing is set by the memory_limit parameter. If the memory limit is too small, Q Capture spills log records to disk until memory is freed. 3. Q Capture puts messages on the send queue and commits the messages to the queue manager at the frequency set by the commit_interval parameter.
