SQL Server Performance

How to interpret index statistics

Discussion in 'SQL Server 2005 T-SQL Performance Tuning' started by jrdevdba, Oct 10, 2007.

  1. jrdevdba New Member

    Hello,
    I ran DBCC SHOWCONTIG on a couple of tables that seem to be involved in long-running queries.
    Are there any general suggestions or interpretation anyone can give based on the results below? In particular, I think the Extent Scan Fragmentation is too high on both tables.
    Also, do these values apply to both table data and indexes, or only to one?
    TABLE level scan performed.
    - Pages Scanned................................: 7234
    - Extents Scanned..............................: 912
    - Extent Switches..............................: 915
    - Avg. Pages per Extent........................: 7.9
    - Scan Density [Best Count:Actual Count].......: 98.80% [905:916]
    - Logical Scan Fragmentation ..................: 0.07%
    - Extent Scan Fragmentation ...................: 48.57%
    - Avg. Bytes Free per Page.....................: 679.8
    - Avg. Page Density (full).....................: 91.60%
    DBCC execution completed. If DBCC printed error messages, contact your system administrator.
    TABLE level scan performed.
    - Pages Scanned................................: 28214
    - Extents Scanned..............................: 3544
    - Extent Switches..............................: 3659
    - Avg. Pages per Extent........................: 8.0
    - Scan Density [Best Count:Actual Count].......: 96.37% [3527:3660]
    - Logical Scan Fragmentation ..................: 0.25%
    - Extent Scan Fragmentation ...................: 61.23%
    - Avg. Bytes Free per Page.....................: 644.1
    - Avg. Page Density (full).....................: 92.04%
    DBCC execution completed. If DBCC printed error messages, contact your system administrator.
    Thanks for any help!
    jrdevdba
  2. satya Moderator

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