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I have a "State" column that has a low cardinality (three possible value), on which most of my queries perform an equality selection (WHERE col = 'blah') AFAIK you need something like a bitmap index to speed this up, which is not available in MySQL. The column value changes from state1 -> state2 -> state -> 3 etc., so I couldn't use partitioning.
How could one speed things up in this situation?

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If you want all rows satisfying the equality condition, index is useless – user1931858 Dec 14 '13 at 19:24
It does not make much sense defining an index to a VERY low cardinality column as in your example - just three possible values. Indexes serve to narrow queriable data. But, I bet your queries rely on other columns, don't they? Can you enrich your problem, with the actual schema and query samples? – Marcus Vinicius Pompeu Apr 20 '14 at 5:26

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