On Tue, 6 Sep 2005, Dan Nelson wrote:
In the last episode (Sep 06), Jason Pyeron said:
there is an unique key index 'pathref_2 (pathref,version)' on this
table.
so why does 'explain select * from files where
(pathref,version)=(129286,0);' scan the whole table?
I have to admit I have never seen this syntax used in a where clause
before.
never thought not to use it, SQL servers are just big set processing
engines.
Does "where pathref=129286 and version=0" optimize any better?
yes, it scans only one row.
A quick test of mysql-5.0.11 indicates that it doesn't use indexes at
all with the (field1,field2,..)=(value1,value2,..) syntax. Feel free
to file a bug :)
http://bugs.mysql.com/13024
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