April 1, 2009 at 12:44 pm
I am planning to replace some _wa_sys indexes with permenent indexes on the table. Some of the _wa_sys indexes on our database table shows the row mod ctr as 43456 ( I ran the update statistics 3 weeks ago on this table, and this index got created with this rowmodctr within the 3 weeks time)
Let me know your thoughts on replacing these dynamically generated indexes with thes large rowmod ctr values with permenent indexes? I dont want to replace those if it will not improve in performance wise.
April 1, 2009 at 3:08 pm
From http://support.microsoft.com/kb/819953
The naming convention for the auto created statistics is _wa_sys_
(where is the object_id of the table in hexadecimal format).
These are not true indexes, but rather measure the distribution of data for a given index or column and are utilized by the query optimizer in generating the query plan.
April 1, 2009 at 3:30 pm
retheeshts (4/1/2009)
I am planning to replace some _wa_sys indexes with permenent indexes on the table.
Those aren't indexes
http://sqlinthewild.co.za/index.php/2008/11/04/what-are-statistics-and-why-do-we-need-them/
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
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