Home Page for the TeradataForum
 

Archives of the TeradataForum

Message Posted: Wed, 14 Oct 2009 @ 10:11:03 GMT


     
  <Prev Next>   <<First <Prev Next> Last>>  


Subj:   Re: Stats not being used by optimizer
 
From:   Dieter Noeth

prahlad.k.patidar wrote:

  We have a complex query running against Teradata 12.  


  When I see explain plan for this after running diagnostic helpstats on for session, it recommends certain sets of collumns for stats collection but stats for all those columns exists.  


  Still why is it giving these recommendation? All stats are up to date.  


There was a problem with helpstats recommending existing stats. But i think this should have been fixed already.


  What could be reason, it optimizer not reading stats properly? if so then can we say stats collected on columns used by joins and where clause do not always help.  


If the optimizer can't use existing stats (e.g. because there's a calculation on that column ) the confidence level will go down to "no confidence".


Dieter



     
  <Prev Next>   <<First <Prev Next> Last>>  
 
 
 
 
 
 
 
 
  
  Top Home Privacy Feedback  
 
 
Copyright for the TeradataForum (TDATA-L), Manta BlueSky    
Copyright 2016 - All Rights Reserved    
Last Modified: 15 Jun 2023