Db2 Tools for z/OS

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Db2 Log Analysis: Huffman Compression Support (PH24753)

By Robert Bersano posted Mon July 06, 2020 05:01 PM


Db2 for z/OS V12 Function level 504 introduced support for compression of Db2 data with IBM Z hardware-based entropy encoding (Huffman) compression with APAR PH04424.  Huffman compression uses IBM z14 hardware to compress data before it is stored and to decompress the data that is retrieved from a page in the buffer pool.  In many cases, using Huffman compression can significantly reduce the amount of disk space needed to store data and improve buffer pool performance, but the compression ratio that can be achieved depends on the characteristics of the data. 

Previously, IBM Db2 Log Analysis Tool for z/OS did not support Huffman compression and an error message “ALAA741E-Huffman compression is not currently supported” was issued if a tablespace that uses this compression was found in the result set.  But recently full Huffman compression support for Log Analysis Tool has been released with Log Analysis APAR PH24753.  To be able to compress records with a Huffman enabled dictionary, the processor must be z14 class or subsequent hardware. At the same time records, that were compressed on z14 using Huffman compression, can be expanded on z13 or lower via a software expansion routine.  So, both the hardware expansion routine and the software expansion method were implemented into Log Analysis Tool to provide full support of Huffman compression. 

As a result, IBM Db2 Log Analysis Tool continues to ensures high availability and complete control over your data integrityD


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1 comment



Sun July 12, 2020 03:40 PM

Users love two phase reporting of the Db2 Log Analysis Tool, and support for Db2 continuous delivery another capability clients appreciate very much.