SQL Server Performance

Quertion about how to understand the output of the DBCC SHOW_STATISTICS

Discussion in 'Performance Tuning for DBAs' started by zhenyuanDeng, Nov 23, 2007.

  1. zhenyuanDeng New Member

    As i know, when i use DBCC SHOW_STATISTICS(A,ix_1) command, i will get the message about the statistics of table A.
    I don't understand why i use the command DBCC SHOW_STATISTICS(A,ix_1) , it show me the "RANGE_ROWS" and "EQ_ROWS" are all long(ie: 200, 4000), but when i use the command DBCC SHOW_STATISTICS(A,ix_1) WITH HISTOGRAM_STEPS, the "RANGE_ROWS" is a decimal(ie:4.2528058E-3), how can i understand the output, i am puzzleing, any help will be usefull, thanks.
  2. Luis Martin Moderator

    This is a 2005 question no 2000.
    STAT_HEADER | DENSITY_VECTOR | HISTOGRAM [ , n ]

    Specifyingone or more of these options limits the result sets returned by thestatement to the specified option. If no options are specified, allstatistics information is returned.
    Check:
    http://msdn2.microsoft.com/en-us/library/ms174384.aspx
  3. zhenyuanDeng New Member

    Why the next four commands' output different ?
    1 DBCC SHOW_STATISTICS(ord_items, IX_ORD_ITEMS_product) WITH STAT_HEADER
    2 DBCC SHOW_STATISTICS(ord_items, IX_ORD_ITEMS_product) WITH DENSITY_VECTOR
    3 DBCC SHOW_STATISTICS(ord_items, IX_ORD_ITEMS_product) WITH HISTOGRAM_STEPS
    4 DBCC SHOW_STATISTICS(ord_items, IX_ORD_ITEMS_product)
    The third command's output "EQ_ROWS" is 3000, but the last command's is a decimal looks like 1.92324424E-4
    why?

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