Primary AND Index keys for table column?

[bunner_bob]

I've set up some multi-column indexes to speed retrievals, and one of them includes the primary key. PhpMyAdmin tells me "PRIMARY and INDEX keys should not both be set for column 'id'"

True? I thought I wanted to include all the columns that would be part of a "where" clause. Leaving this one out won't kill the index, but it seems it will be less effective without it. However, I don't want to be a bad coder - what should I do?

• Bob

[bastien]

mysql tends to use just one index when running a query. I would suggest simply testing it. Add the column to the index and see what the perfomance is...then remove it and test again