0

In SQL Server 2012, I am seeing large cardinality estimate discrepancies for a columnstore index scan. It looks like statistics have been generated for the index, but I don't see any details in DBCC SHOW_STATISTICS (this may not be supported for columnstore indexes).

Can statistics be updated for a columnstore index, or are there other ways to address this large cardinality estimate discrepancy? I have not been able to find definitive documentation but noted that UPDATE STATISTICS failed because statistics cannot be updated on a columnstore index. UPDATE STATISTICS is valid only when used with the STATS_STREAM option exists in sys.sysmessages.

  • Please read Niko's post... it shows how limited your control over stats is even with a writable columnstore index in SQL Server 2014, never mind the read-only version introduced in 2012. – Aaron Bertrand Apr 30 '15 at 16:13
  • Thanks Aaron. Would your recommendation then be to ignore cardinality estimate discrepancies for a columnstore index scan operator when tuning queries that contain such operators in the execution plan? If not, would rebuilding or dropping and recreating the index be worth pursuing? – slachterman May 4 '15 at 15:06

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.