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  1. #1
    Join Date
    Sep 2005
    Posts
    3

    Unanswered: Table compression not working

    Hi

    DB2 9.7 FP6, AIX 6.1, non dpf environment.

    We have few tables on which compression is enabled. The tables are partitioned.
    After the history data load, we saw that there is no compression.From version 9.7 fp1, the dictionary gets built only after data reaches some threshold. As per the solution suggested in documentation, we ran reorg on these tables with resetdictionary clause. Still the compression is nil. The PCTPAGESAVED is 0 for these tables.
    Does this has anything to do with pagesize? These tables are in tablespaces with 32k pagesizes. The avgrowlength is between 600-800.
    Am I missing any other parameters which need to be taken care of?
    Please advise.

    Thanks

  2. #2
    Join Date
    Apr 2006
    Location
    Belgium
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    2,514
    Provided Answers: 11
    how did you verify this ?
    maybe runstats is needed ?
    or look at for complete procedure - maybe something is missing..
    Enabling compression in an existing table - IBM DB2 9.7 for Linux, UNIX, and Windows
    Best Regards, Guy Przytula
    Database Software Consultant
    Good DBAs are not formed in a week or a month. They are created little by little, day by day. Protracted and patient effort is needed to develop good DBAs.
    Spoon feeding : To treat (another) in a way that discourages independent thought or action, as by overindulgence.
    DB2 UDB LUW Certified V7-V8-V9-V9.7-V10.1-V10.5 DB Admin - Advanced DBA -Dprop..
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  3. #3
    Join Date
    Sep 2005
    Posts
    3
    Hi Guy

    For verifying, I did following things:
    1> checked the fields PCTROWSCOMPRESSED and PCTPAGESAVED in table syscat.datapartitions. They are 0.
    2> checked the fields PCTROWSCOMPRESSED and PCTPAGESSAVED in table syscat.tables. They are also 0.
    3> Checked the filesystem utilization using df -g. There is no change.

    The STATS_TIME field in syscat.tables shows that they were updated yesterday after completion of reorg.
    Before data load, tables were altered with COMPRESS YES option to enable compression. I can see that field COMPRESSION has value 'R' for these tables in syscat.tables.

    Please advise on anything which I might have missed out.

    Thanks

  4. #4
    Join Date
    Apr 2006
    Location
    Belgium
    Posts
    2,514
    Provided Answers: 11
    it might be that compression is not effective for this table
    have you run inspect before with compression estimate
    Best Regards, Guy Przytula
    Database Software Consultant
    Good DBAs are not formed in a week or a month. They are created little by little, day by day. Protracted and patient effort is needed to develop good DBAs.
    Spoon feeding : To treat (another) in a way that discourages independent thought or action, as by overindulgence.
    DB2 UDB LUW Certified V7-V8-V9-V9.7-V10.1-V10.5 DB Admin - Advanced DBA -Dprop..
    Information Server Datastage Certified
    http://www.infocura.be

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