May 6, 2011 at 3:31 pm
Hi,
I need your suggestion..
After running the rebuild/Reorg Index job, can I include the Update statistics Task as a next task to the "Index Rebuild Job"? Or, would you suggest to run only the Index Rebuild/Reorg job under Maintenance Plans and running the statistics Update task using 'dbcc updatestats'?
Which one would be better in terms of altogether utilisation?
-Sourav
Thanks.
May 6, 2011 at 3:47 pm
Use the Update Statistics task, but select the option for 'column statistics only' as index stats will have been updated by the index rebuild
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
May 6, 2011 at 3:48 pm
Please note:
1) Index rebuild works by re-creating the index internally again and when that has been achieved, it drops the existing index where as index reorganize is the process of physically re-organizing the leaf nodes of the index.
2) During the index rebuild process, the statistics are also re-computed – same as when a new index gets created. Reorganize on the other hand does not update the statistics. Reorganize essentially just swaps one page with another and thus does not require free space for this operation like rebuild does. Infact, reorganize can free up some pages as it does the reorg in two phases – compaction and defrag. A reorganize can remove almost all of the logical fragmentation but it cannot necessarily fix extent fragmentation in which the previous and the next extents are physically contiguous.
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May 7, 2011 at 2:34 am
Thanks Gail.
So, are you suggesting me to use 'the database maintenance task' to rebuild the stats?
Thanks.
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