Re: Optimizing query

[Jørgen Løland]

Hi jr wakabayashi,

There are many complicating factors with this query. I'll give you a hint to start with:

There are two RIGHT JOINs. RIGHT and LEFT JOINs are much harder to run in an optimal way than inner joins. The reason is that MySQL has to put the outer table first in the join order. Depending on the database schema and amount of data in the tables, this can lead to significantly lower performance.

Please provide the output of these commands so I'm able to tell you more:

* EXPLAIN for the query
* SHOW CREATE TABLE for all the involved tables

Also, please enclose the output in [code ] [/code ] (remove the space) tags for readability.

Hope this helps,
Jørgen Løland
Software Engineer, MySQL, Oracle
jorgenloland.blogspot.com