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author | Tom Lane <tgl@sss.pgh.pa.us> | 2000-01-28 03:22:36 +0000 |
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committer | Tom Lane <tgl@sss.pgh.pa.us> | 2000-01-28 03:22:36 +0000 |
commit | 003dd965d2380823624f58d0d0cf72c4edc3bcb4 (patch) | |
tree | 4d4dde8f97203873e5d03ee6ecb6d900bcf036fe /doc/src/sgml/ref/commit.sgml | |
parent | b53955f38aa3832b84970c806e1afdd7d3053d9e (diff) | |
download | postgresql-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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