I am trying to optimize a query that uses a group by on a varchar(255) column. The column has a large enough cardinality that a 10 character partial index uniquely covers over 99% of all values. I was hoping that this partial index would be able to help with the group by (though obviously not as much as a full index), but it seems that only full indexes can be used with group by optimizations. Would anyone be able confirm this one way or another? I am using 5.1.45 with InnoDB Storage Engine.
I ended up just adding the full index for the performance, but would like to know what's going on for my personal knowledge. Any insights would be great. Thanks. Les Fletcher -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
