----- Original Message -----
> From: "Cabbar Duzayak" <cabbar@stripped>
>
> Is there a way of looking at how mysql builds the query plan and
> executes it for a given query? EXPLAIN is definitely a useful tool, but it is
> not exact (shows approximations as far as I can see), furthermore I want
> something like how the predicates were applied (before or after
> JOINS), which indexes were used, etc.
>
> Basically, Oracle's EXPLAIN PLAN and SQL TRACE do this, and it is
> very very useful for optimizing queries. Don't get me wrong, I love mysql, but
> with mysql, you optimize queries more by trial and error, instead of
> understanding what exactly is going on.
The Percona Toolset has pt-visual-explain and some other useful tools.
There's also SHOW PROFILE in mysql itself, look at
http://dev.mysql.com/doc/refman/5.0/en/show-profiles.html for more about that.
All in all, though, I'm not sure you can go quite as deep as you can in Oracle.
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