Replication Guide and Reference

Improved Performance for the Capture and Apply Programs

The Capture and Apply programs capture and replicate data faster and more efficiently.

• Reduced Apply program connect processing:

  Grouped subscriptions reduce the number of times the Apply program connects to the source, control, and target servers. For example, when maintaining 40 copies, a group replication subscription replaces 40 individual subscriptions. Connect processing is reduced 40:1.

• Apply program notification:

  The Capture program now notifies the Apply program when there are changes to be applied to avoid unnecessary dynamic SQL and joins at the source site.

• Non-blocking protocol:

  • The Apply program uses a new non-blocking protocol with the Capture program, taking advantage of uncommitted read isolation to avoid contention and allows for a 100% Capture duty cycle, regardless of the Apply program's activity.

  • The protocol with the Apply program is nonlocking, allowing you to choose the Capture program commit interval independently of the DB2 lock timeout value. The Apply program processes do not timeout if the Capture program commit interval is increased, which reduces the PREPARE and COMMIT costs of change capture.

• Static SQL performance for the Capture program:

  The Capture program benefits from changes in DB2 for MVS Version 5.1, which allow dynamic SQL statements to be cached in the EDM pool, just as static SQL statements are cached. These changes effectively let the Capture program, a dynamic SQL application, run with static SQL performance.

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