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This commit is contained in:
Tom Lane 2003-12-29 21:44:49 +00:00
parent 07f9f4d413
commit b53ca9bbcb
1 changed files with 5 additions and 1 deletions
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6
src/backend/optimizer/path/clausesel.c
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@ -8,7 +8,7 @@
* *
* *
* IDENTIFICATION * IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/clausesel.c,v 1.61 2003/11/29 19:51:50 pgsql Exp $ * $PostgreSQL: pgsql/src/backend/optimizer/path/clausesel.c,v 1.62 2003/12/29 21:44:49 tgl Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -108,6 +108,10 @@ restrictlist_selectivity(Query *root,
* If the calculation yields zero or negative, however, we chicken out and * If the calculation yields zero or negative, however, we chicken out and
* use a default estimate; that probably means that one or both * use a default estimate; that probably means that one or both
* selectivities is a default estimate rather than an actual range value. * selectivities is a default estimate rather than an actual range value.
*
* A free side-effect is that we can recognize redundant inequalities such
* as "x < 4 AND x < 5"; only the tighter constraint will be counted.
*
* Of course this is all very dependent on the behavior of * Of course this is all very dependent on the behavior of
* scalarltsel/scalargtsel; perhaps some day we can generalize the approach. * scalarltsel/scalargtsel; perhaps some day we can generalize the approach.
*/ */