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authorTom Lane <tgl@sss.pgh.pa.us>2000-01-28 03:22:36 +0000
committerTom Lane <tgl@sss.pgh.pa.us>2000-01-28 03:22:36 +0000
commit003dd965d2380823624f58d0d0cf72c4edc3bcb4 (patch)
tree4d4dde8f97203873e5d03ee6ecb6d900bcf036fe /doc/src/sgml/ref/commit.sgml
parentb53955f38aa3832b84970c806e1afdd7d3053d9e (diff)
downloadpostgresql-003dd965d2380823624f58d0d0cf72c4edc3bcb4.tar.gz
postgresql-003dd965d2380823624f58d0d0cf72c4edc3bcb4.zip
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.
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