System Indexes: Can you reorg?

  • I have created my own reorg process to reorg the tables and indexes through use of DBCC DBREINDEX and DBCC INDEXDEFRAG. However, my process will not touch system created indexes. Do I need to be cautious with these indexes? Is there anything I can even do about them? I haven't been able to find any documentation on how or why they are created.

    Example

    Table:AGENTS

    IndexName: tAGENTS

    IndexID: 255

    ScanDensity: 41

    LogicalFrag: 100

    Thanks,

    CyGradFan

  • I'm not sure you can or that you want to. These tables are not in general, accessed that often.

    Steve Jones

    sjones@sqlservercentral.com

    http://www.sqlservercentral.com/columnists/sjones

    http://www.dkranch.net

  • Let me clarify. These indexes are on user tables and not system tables. I have not created any of these indexes, but they seem to 'magically' appear on tables with some size to them. All of theses tables have indexes I defined on them.

  • If you are talking about indexes that start with "WA_", those are auto-statistics created by the query optimizer on fields that it believes would be helpful to have stats on. They can show up as "indexes" in some places in the GUI, but they are not true indexes. You may wish to examine them for possible promotion into real indexes, based upon query activity against the table.

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