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Re: Why doesn't reorg rebuild update all the statistics

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Hmmmm....I don't recall that.   I did mention that hash based stats worked in sp13x vs. some had issues prior to that.   One thing that is interesting, is that if you drop an index, it doesn't remove the column statistics for that index - just the multi-column density stats.   So I am not sure if a reorg rebuild is supposed to update the column stats or not.   One consideration on DOL tables is that if there are rows that were marked for deletion, but the HKGC queue was overrun, it could impact the column histograms. 

 

There is a note in the 16.0 documentation:

 

"Running reorg rebuild table_name updates the statistics for all leading index columns.

However, running reorg rebuild table_name index_name does not automatically update the

statistics. Instead, the SAP ASE server automatically updates index statistics when you

run reorg rebuild index_name if the update includes a suffiecient change in data to affect its

plan choice and performance."

 

As a result, I would assume that running a reorg rebuild is insufficient for good column histograms and would always suggest running update index statistics to be sure.

 



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