When PLOG processing is being considered by a customer interested in Change Data Capture (CDC) against ADABAS, it should be understood from the outset that PLOG processing will be an ongoing activity.  Every transaction that occurs within an ADABAS database will have to be at least cursorily examined to see whether it is a transaction against the file or files of interest. For all transactions selected, each transactional record will  need to be decompressed.

While other processing will be involved in properly handling PLOG data, the decompression processing is particularly resource intensive.  As a result, it is highly advisable for any ADABAS customer who is contemplating doing ongoing PLOG / CDC processing to have an understanding of how long CDC processing might take, and how to schedule this processing into the available batch time windows.

We have prepared this page for the expressed purpose of demonstrating the performance characteristics of the NatCDC / NatCDCSP solution, and we invite you to compare this performance information to other available solutions.

The following execution times were captured at one of our existing NatCDC customers who supplied us with these times from one of their worst / busiest transactional days that they had in recent history.  This was a day where their primary production ADABAS databases created Twenty-two (22) separate PLOG tape cartridges.

These tapes were then processed in the following manner:

  1. All Twenty-two (22) tapes were initially processed through the ADASEL utility, and this utility was instructed to capture changes that occurred against four (4) files that required CDC processing and to split the individual transactions from each of these four files into their own respective dataset.  The results from this execution can be seen in the following section entitled ADASEL Execution Results.
     
  2. Each of the 4 datasets were then simultaneously processed using NatCDC-generated processing to drop unneeded fields, place the output into a fixed-length format, sort this fixed-length output, produce a “Delta” of the transactional changes for each individual record, and perform any required ADABAS to ASCII data transformations.  The results from these executions can be seen in the following section entitled NatCDC Processing Results.
     

As can be seen in the following results, ADASEL selected 940,363 transactional records that were associated with the 4 source files from the Twenty-two (22) tape cartridge input, and then decompressed all 940,363 transactional records into 15,800 cylinders in 110.26 Minutes.  If we ignore the processing time required to read the Hundreds of Thousands of transactional records that were not of interest to CDC processing (and were therefore bypassed), as well as time lost waiting for possible tape mounts, we can roughly calculate ADASEL’s ability to select and decompress transactional records of interest at being approximately 142 transactional records a second.

For the remaining processing, we can see a range of between 309 records per second to 6,152 records per second. 

With these numbers as a benchmark, this customer was able to process their worst transactional day against the four (4) files of interest in approximately 3.5 hours, with virtually all of this being sequential processing that can allow other ADABAS activities to continue.

ADASEL EXECUTION RESULTS

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NatCDC Processing Results
Subsequent to the execution of ADASEL, each output file was then concurrently processed through a NatCDC generated JCL stream which performed 3 steps (a step-by-step description of the steps involved can be found on the NatCDC Operation and Architecture Page):

The above processing, when applied to each of the four files of interest, yielded the following results:

 

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PLOG Processing Performance

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