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#1 (**permalink**) 02-28-2008, 10:27 AM

I am working on a project with a large poorly designed codebase.
I want to refactor the database, which will require dropping tables
and indexes.
There are many tables and indexes that were just put there because the
guy thought it might be useful.

So my question is, is there any way to determine which indexes are
actually used?
Any recommendations on how to procede would be greatly appreciated.

We are using mysql 4.1, we tried to upgrade to mysql 5, but it took 3
weeks to reindex the database.

thanks

Kal

#2 (**permalink**) 02-28-2008, 10:27 AM

>I am working on a project with a large poorly designed codebase.
>I want to refactor the database, which will require dropping tables
>and indexes.
>There are many tables and indexes that were just put there because the
>guy thought it might be useful.
>
>So my question is, is there any way to determine which indexes are
>actually used?
>Any recommendations on how to procede would be greatly appreciated.
>
>We are using mysql 4.1, we tried to upgrade to mysql 5, but it took 3
>weeks to reindex the database.

The EXPLAIN command will show what indexes are used for a particular
query. You'll need to use it for all your queries, and decide which
queries are used most often and are the most important to speed up.

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how do you know which indexes are actually used