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postgres/src/backend/optimizer/prep/prepqual.c
Tom Lane 003dd965d2 Apply the heuristic proposed by Taral (see pgsql-general archives for
2-Oct-98 or TODO.detail/cnfify) to decide whether we want to reduce
WHERE clause to CNF form, DNF form, or neither.  This is a HUGE win.
The heuristic conditions could probably still use a little tweaking to
make sure we don't pick CNF when DNF would be better, or vice versa,
but the risk of exponential explosion in cnfify() is gone.  I was able
to run ten-thousand-AND-subclause queries through the planner in a
reasonable amount of time.
2000-01-28 03:22:36 +00:00

25 KiB