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Adriano,
Please clarify, are you proposing that index should be used, or some other optimization? Thanks for clarifying the ticket summary/description.
I wonder, though, given the limited selectivity of a Boolean based index, would such an index actually provide any benefit? {The cost of the random IO involved in checking the current value of the field would, in many cases, out-weight the value of using the index, thus making a NATURAL table scan more efficient} There could be multi-segmented boolean fields in a index, that when combined would have a better selectivity.
Currently even with an explicit PLAN the index is not usable with IS DISTINCT FROM. I agree that Boolean fields present in multi-segment indexes should be used.
But, at the moment, this ticket suggests that even single-segment Boolean indexes would be considered... Are you proposing that they would be considered? Or only in multi-segment index use cases? |
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Improvement
Open
Major
Improve optimizer to consider index usage for IS DISTINCT FROM with boolean fields
CORE-5986, as a solution for it is to treat IS NOT {TRUE | FALSE | NULL | UNKNOWN} as IS DISTINCT FROM (i.e. blr_equiv).