From: "Terry Spencer"
> An index exists on all three columns referred to, in addition to a
> combination of del and signoff.
>
> The indexes are listed as possible keys, but none used by the query; key =
> null. Can anyone suggest why? How can I optimise this?

How many records are there in the table? If MySQL's query optimizer thinks
that the query will return more than approx. 30% of the records it is
probably faster to do a tablescan than to use the index and access the
records one by one.

Regards, Jigal.


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