[Progress Communities] [Progress OpenEdge ABL] Forum Post: RE: Question about the performance of ABL queries resolved by multiple indexes

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dbeavon

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If the selectivity is bad, then I can't think how it would ever make sense to use the index. The problem is that Progress ABL doesn't have a way to KNOW the selectivity is bad, and so it will use the index anyway. This feature might have been good one to pair with some sort of run-time optimization hint ("FOR EACH ... USE COST-OPTIMIZER"). I suspect that you need even more experienced DBA's to manage these indexes (as compared to conventional indexes). Otherwise these types of indexes may cause as many problems as they solve. Just to be clear, I'm not opposed to the concept of using multiple indexes to resolve a query as long as they all have fairly good selectivity. But it is these single-field indexes with inconsistent selectivity that I have a problem with.

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