If you sort or search on both fieldA and fieldB frequently, a single index on the both of them will work better than one index for each of them. Also, if you have an index which covers (A, B, C), that can also be used just like an index on (A, B) or an index on A alone, but not B alone or C alone.

In reply to Re: OT: Indexes in MySQL by kyle
in thread OT: Indexes in MySQL by isync

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