From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 29 Dec 2003 21:44:49 +0000 (+0000)
Subject: Improve comment.
X-Git-Tag: REL9_0_0~13617
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=b53ca9bbcb2892c6c24f7ab4aa087b35ef1222e6;p=pg-rex%2Fsyncrep.git

Improve comment.
---

diff --git a/src/backend/optimizer/path/clausesel.c b/src/backend/optimizer/path/clausesel.c
index 17cde28aec..7e5456d85b 100644
--- a/src/backend/optimizer/path/clausesel.c
+++ b/src/backend/optimizer/path/clausesel.c
@@ -8,7 +8,7 @@
  *
  *
  * 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
  * use a default estimate; that probably means that one or both
  * 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
  * scalarltsel/scalargtsel; perhaps some day we can generalize the approach.
  */