With ADABAS 6 and previous versions, there was only one Software AG ADABAS utility that handled ADABAS Protection Logs (PLOGs), and this utility was ADASEL.
With the release of ADABAS 7, a new utility was delivered which was theoretically designed to better address the requirements of Data Warehouse Change Data Capture (CDC) processing, and this utility is ADACDC. (The ADASEL utility continues to remain available with ADABAS 7).
While both ADASEL and ADACDC are fully supported by the NatWorks product NatCDC, the question arises as to which utility should be used. NatWorks has extensively reviewed the potential use of both utilities, and we therefore offer the following summarization / comparison of these two approaches.
Where ADASEL and ADACDC are the same:
- Both utilities use PLOG data as input.
- Both utilities produce PLOG output in a decompressed form.
- Both utilities have the potential to output transactions against a single file in variable record length format, due to the fact that individual records within the same file can contain differing occurrences of Multi-Valued fields (MUs) and Periodic-Groups (PEs).
- Both utilities make no attempt to convert internal ADABAS field formats (such as Date and Time) to a format usable to a Data Warehouse.
Where ADASEL and ADACDC differ:
- ADASEL has the optional ability to “split out” transactions for up to 20 selected files (including expanded files). ADASEL can also be used without the limitation of 20 files if all transactions of interest are written to the same file.
- ADACDC produces a single output file that contains all transactions for selected files, but does no “splitting”.
- ADASEL does not have the ability to automatically produce “delta changes”.
- ADACDC does have the ability to automatically produce “delta changes”.
- ADASEL’s “data header” information is suitable for both auditing and CDC processing.
- ADACDC’s “data header” information is only suitable for CDC processing.
- ADASEL mirrors ADABAS’ “optimistic update” approach.
- ADACDC can support “optimistic update”, and can also support a “committed update” approach.
- ADASEL’s processing does not include any internal sort processing.
- ADACDC’s processing includes an internal SORT process that is integral to produce “delta changes”.
- ADASEL produces Before and After images of all transactions.
- ADACDC produces only the last image of a record with an add, update, delete indicator and does not provide before and after imaging.
ADASEL provides better audit capabilities due to the mirroring of optimistic processing and the delivery of before/after images. When ADASEL is used in conjunction with NatCDC processing, full “delta change” processing is supported.
ADACDC is only useful for “delta change” processing, and the output of ADACDC still requires further processing (I.E. manual coded processes) prior to passing this data into a target Data Warehouse.
While NatWorks’ NatCDC product supports either the ADASEL or ADACDC utility, we recommend utilizing the ADASEL for core PLOG processing. The features that ADACDC provides that ADASEL does not inherently provide is addressed by NatCDC.
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