How can I see how the MySQL database engine resolves queries internally?

Question

I use MySQL as my database engine. How can I see how the database engine resolves queries internally?

Answer 1

It'd help if we know what you wanted to use the tool for.

From my experience, even if such a thing were available for MySQL, it's not something I'd use for analysing/tuning performance. For general database setup I've found mysqltuner.pl does a very good job. While for schema / query tuning, I use mysql_slow_log_parser along with some crude scripts to prioritize problem areas.

For monitoring availability, I use Nagios - which also monitors all sorts of other services.

Some discussion of the same topic on Stackoverflow

There's several websites and books on the subject - mysqlperfromanceblog is a good one

Answer 2

If all you want to see is how sql queries are resolved internally, use EXPLAIN (aka DESCRIBE)

"The EXPLAIN statement can be used either as a way to obtain information about how MySQL executes a SELECT statement or as a synonym for DESCRIBE"