Re: Hints

  • From: Laimutis.Nedzinskas@xxxxxx
  • To: Greg Rahn <greg@xxxxxxxxxxxxxxxxxx>
  • Date: Thu, 18 Aug 2011 11:17:27 +0300

Right. Thank you.
transformations - yes, those are something which can be characterized as a
creative part of the optimizer design :)


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  From:       Greg Rahn <greg@xxxxxxxxxxxxxxxxxx>                               
                                                                      
                                                                                
                                                                      
  To:         Laimutis.Nedzinskas@xxxxxx                                        
                                                                      
                                                                                
                                                                      
  Cc:         oracle-l@xxxxxxxxxxxxx                                            
                                                                      
                                                                                
                                                                      
  Date:       2011.08.18 11:01                                                  
                                                                      
                                                                                
                                                                      
  Subject:    Re: Hints                                                         
                                                                      
                                                                                
                                                                      





Having FKs allows for table elimination transformations:
http://blogs.oracle.com/optimizer/entry/why_are_some_of_the_tables_in_my_query_missing_from_the_plan


2011/8/17  <Laimutis.Nedzinskas@xxxxxx>:
> As for optimizer and foreign keys then it considers only uniqueness.
> F-keys have no effect on CBO whatsoever. Correct me if I am wrong.

--
Regards,
Greg Rahn
http://structureddata.org



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