Table of Contents

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  1. Preface
  2. Change Data Capture Introduction
  3. PowerExchange Listener
  4. PowerExchange Condense
  5. DB2 for i5/OS Change Data Capture
  6. Remote Logging of Data
  7. Introduction to Change Data Extraction
  8. Extracting Change Data
  9. Monitoring CDC Sessions
  10. Managing Change Data Extractions
  11. Tuning CDC Sessions
  12. Appendix A: DTL__CAPXTIMESTAMP Time Stamps

CDC Guide for i5/OS

CDC Guide for i5/OS

Example 1. Subpacket Commit and UOW Count

Example 1. Subpacket Commit and UOW Count

This example uses the
Maximum Rows Per commit
and
UOW Count
attributes to control commit processing.
The change data is composed of UOWs of the same size. Each UOW contains 1,000 change records.
The following table describes the commitment control attribute values that this example uses:
Attribute
Value
Maximum Rows Per commit
300
Minimum Rows Per commit
0, which disables this attribute
Real-time Flush Latency in milli-seconds
0, which is equivalent to 2 seconds
UOW Count
1
Based on the maximum rows value, PWXPC flushes the data buffer after reading the first 300 records in a UOW. This action commits the change data to the targets. PWXPC continues to commit change data to the targets every 300 records.
PWXPC commits on UOW boundaries only for the UOW count and real-time flush latency interval. If the real-time flush latency interval expires before PWXPC reads 300 change records, PWXPC still commits based on the maximum rows value because that threshold is met before a UOW boundary occurs.
When the end of the UOW is read, PWXPC commits the change data because the
UOW Count
value is 1. PWXPC resets the UOW and maximum row counters and the real-time flush latency timer each time it commits. Because all of the UOWs have the same number of change records, PWXPC continues to read change data and to commit the data to the targets at the same points in each UOW.
In this example, PWXPC commits change data at the following points:
  • 300 change records based on the maximum rows value
  • 600 change records based on the maximum rows value
  • 900 change records based on the maximum rows value
  • 1,000 change records based on the UOW count value

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