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Q: When should I use COMMIT in DB2?
Answer:
COMMIT saves all changes since the last COMMIT and releases locks.
When to COMMIT:
- After processing a logical unit of work
- Periodically in long-running batch (every N records)
- Before ending the program successfully
Frequency Guidelines:
- Too frequent: Performance overhead
- Too rare: Lock contention, large log
- Typical: Every 100-1000 records in batch
Best Practice:
MOVE 0 TO WS-COMMIT-COUNT.
PERFORM PROCESS-RECORD.
ADD 1 TO WS-COMMIT-COUNT.
IF WS-COMMIT-COUNT >= 500
EXEC SQL COMMIT END-EXEC
MOVE 0 TO WS-COMMIT-COUNT
END-IF.
Note: In CICS, syncpoint (COMMIT) happens automatically at task end. Explicit SYNCPOINT is rarely needed.
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Q: How to SYNCPOINT?
Answer:
SYNCPOINT commits changes. EXEC CICS SYNCPOINT. Makes updates permanent. Or SYNCPOINT ROLLBACK undoes since last sync. Implicit syncpoint at task end. Use for transaction consistency.
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Q: Explain recoverable resources
Answer:
Recoverable resources participate in syncpoint. File with RECOVERY(YES). TS MAIN with AUX. Changes backed out on rollback. Non-recoverable not protected. Define appropriate for data.