Re: [GENERAL] Performance issue with libpq prepared queries on 9.3 and 9.4

Tom Lane-2 wrote
> In the meantime, I assume that your real data contains a small percentage
> of values other than these two?  If so, maybe cranking up the statistics
> target would help.  If the planner knows that there are more than two
> values in the column, I think it would be less optimistic about assuming
> that the comparison value is one of the big two.

Is there any value (or can value be added) in creating a partial index of
the form:

archetype IN ('banner','some other rare value')

such that the planner will see that such a value is possible but infrequent
and will, in the presence of a plan using a value contained in the partial
index, refuse to use a generic plan knowing that it will be unable to use
the very specific index that the user created?

David J.





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