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Fix set_append_rel_pathlist() to deal intelligently with cases where

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substituting a child rel's output expressions into the appendrel's restriction
clauses yields a pseudoconstant restriction.  We might be able to skip scanning
that child rel entirely (if we get constant FALSE), or generate a one-time
filter.  8.3 more or less accidentally generated plans that weren't completely
stupid in these cases, but that was only because an extra recursive level of
subquery_planner() always occurred and allowed const-simplification to happen.
8.4's ability to pull up appendrel members with non-Var outputs exposes the
fact that we need to work harder here.  Per gripe from Sergey Burladyan.
This commit is contained in:
Tom Lane
2009-07-06 18:26:30 +00:00
parent bf6570abef
commit 9b27eab71c
4 changed files with 114 additions and 58 deletions
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5
src/include/optimizer/restrictinfo.h
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@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/optimizer/restrictinfo.h,v 1.44 2009/05/09 22:51:41 tgl Exp $
* $PostgreSQL: pgsql/src/include/optimizer/restrictinfo.h,v 1.45 2009/07/06 18:26:30 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -30,8 +30,11 @@ extern RestrictInfo *make_restrictinfo(Expr *clause,
extern List *make_restrictinfo_from_bitmapqual(Path *bitmapqual,
bool is_pushed_down,
bool include_predicates);
extern List *make_restrictinfos_from_actual_clauses(PlannerInfo *root,
List *clause_list);
extern bool restriction_is_or_clause(RestrictInfo *restrictinfo);
extern List *get_actual_clauses(List *restrictinfo_list);
extern List *get_all_actual_clauses(List *restrictinfo_list);
extern List *extract_actual_clauses(List *restrictinfo_list,
bool pseudoconstant);
extern void extract_actual_join_clauses(List *restrictinfo_list,