Tom Lane 107cbb2b90 Fix best_inner_indexscan to return both the cheapest-total-cost and ...

cheapest-startup-cost innerjoin indexscans, and make joinpath.c consider
both of these (when different) as the inside of a nestloop join.  The
original design was based on the assumption that indexscan paths always
have negligible startup cost, and so total cost is the only important
figure of merit; an assumption that's obviously broken by bitmap
indexscans.  This oversight could lead to choosing poor plans in cases
where fast-start behavior is more important than total cost, such as
LIMIT and IN queries.  8.1-vintage brain fade exposed by an example from
Chuck D.

2007-05-22 01:40:42 +00:00

4.8 KiB

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