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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

Target Latency

Target Latency

Target latency is the total time for applying change data to the targets.
This total includes the time that PWXPC takes to extract change data from the change stream and the time that PowerCenter Integration Service takes to apply that change data to the targets. If extraction and apply processing occurs quickly, target latency is low.
The values for the commitment control attributes affect target latency. When you set the commitment control attributes, balance target latency requirements with resource consumption on the PowerCenter Integration Service machine and the target databases.
Lower target latency values result in higher resource use. The increased resource use occurs because the PowerCenter Integration Service must flush the change data more frequently. Also, the target databases must process more commit requests.
The following table describes the default values for the commitment control attributes, which provide the lowest latency:
Attribute
Default
Maximum Rows Per commit
0, which disables this attribute
Minimum Rows Per commit
0, which disables this attribute
Real-time Flush Latency in milli-seconds
0, which is equivalent to 2000 milliseconds or 2 seconds
UOW Count
1
These values decrease target latency because PWXPC commits changes after each UOW or on UOW boundaries. However, these values can have the following drawbacks:
  • Highest resource consumption on the source system, PowerCenter Integration Service machine, and target databases
  • Decreased throughput for the CDC sessions because PWXPC flushes change data too frequently for the PowerCenter Integration Service or target databases to handle this processing
To lower resource consumption and potentially increase throughput for CDC sessions, enter a value greater than the default value for one of the following attributes:
  • Minimum Rows Per commit
  • UOW Count
  • Real-time Flush Latency in milli-seconds
Then disable the other attributes.

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