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DBCC DBREINDEX (aka INDEX REBUILD in 2005) and Statistics Update

So - today I've been made this question.

 

"I have a DB, AUTO_UPDATE_STATISTICS option OFF (very bad idea, anyway :-)), I rebuild my indexes every week. I do not have major changes in my database. As update statistics with fullscan is a side effect of DBCC DBREINDEX (aka INDEX REBUILD in 2005), can I say all my statistics are fine and up to date?"

 

Well... No :-(

In fact, statistics created from DBCC DBREINDEX (aka INDEX REBUILD in 2005) are only statistics over indexed columns. Statistics over non-indexed column (the ones named something like _WA_sys) are not managed from these operations. Therefore, if you want these to be up to date you need to turn AUTO_UPDATE_SATTISTICS  ON or to schedule their management in other way.

 

More info can be found at:

Is statistics over non-indexed columns updated by index rebuild?

https://sqlblog.com/blogs/tibor_karaszi/archive/2007/08/09/is-statistics-over-non-indexed-columns-updated-by-index-rebuild.aspx

 

- Beatrice Nicolini -