MySQL Forums
Forum List  »  Optimizer & Parser

Advanced Search
New Topic

Re: Parallel scans
Posted by: Rick James
Date: May 20, 2009 10:39PM

You have pretty much described the "index merge", new with 5.0:
http://dev.mysql.com/doc/refman/5.0/en/index-merge-optimization.html

Your particular example had two things conspiring from picking t2 first (which would have been much more efficient): LEFT JOIN and 'f' being NULLable.

Navigate: Previous Message• Next Message
Options: Reply• Quote


Subject
Views
Written By
Posted
Parallel scans
3847
Steve Fink
May 19, 2009 04:15PM
Re: Parallel scans
2174
Rick James
May 20, 2009 10:39PM


Sorry, you can't reply to this topic. It has been closed.
This forum is currently read only. You can not log in or make any changes. This is a temporary situation.

Content reproduced on this site is the property of the respective copyright holders. It is not reviewed in advance by Oracle and does not necessarily represent the opinion of Oracle or any other party.