https://bugzilla.wikimedia.org/show_bug.cgi?id=16645
Brad Jorsch <[email protected]> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |[email protected] --- Comment #3 from Brad Jorsch <[email protected]> 2008-12-15 20:58:51 UTC --- It could make the difference between MySQL using "const" or "eq_ref" instead of "ref" when planning the query. MySQL doesn't seem to be smart enough to realize the non-UNIQUE key is still going to be unique. I ran the following test: create table foo (i integer not null, j integer not null, unique key key1 (i,j), key key2 (i,j)) engine=InnoDB; -- Insert 100 records into foo, for (0,0) - (9,9) explain select * from foo force index (key1) where i=4 and j=2; | 1 | SIMPLE | foo | const | key1 | key1 | 8 | const,const | 1 | Using index | explain select * from foo force index (key2) where i=4 and j=2; | 1 | SIMPLE | foo | ref | key2 | key2 | 8 | const,const | 1 | Using index | -- Configure bugmail: https://bugzilla.wikimedia.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the assignee for the bug. You are on the CC list for the bug. _______________________________________________ Wikibugs-l mailing list [email protected] https://lists.wikimedia.org/mailman/listinfo/wikibugs-l
