indexing

[crawfd]

I have 10 fields in a table and I need to index two of them. Is it generally a good idea to index more than one field in any given table? I need to index an id field and username field. Is it correct to assume that things woudl run faster if only one field was indexed in a db with a size of around 50,000 rows?

[tsinka]

Hi,

this is a tricky thing 🙂

It depends on your queries especially on the WHERE part of queries or the ON part when joining tables.

A good way is to use

EXPLAIN query

MySQL will return a table containing a description of what indexes will be used. You can then use that output to find the best indexes for a table.

Depending on the queries more than one index might be neccessary.

Post an example query.

Thomas