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Support "x IS NOT NULL" clauses as indexscan conditions. This turns out

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to be just a minor extension of the previous patch that made "x IS NULL"
indexable, because we can treat the IS NOT NULL condition as if it were
"x < NULL" or "x > NULL" (depending on the index's NULLS FIRST/LAST option),
just like IS NULL is treated like "x = NULL".  Aside from any possible
usefulness in its own right, this is an important improvement for
index-optimized MAX/MIN aggregates: it is now reliably possible to get
a column's min or max value cheaply, even when there are a lot of nulls
cluttering the interesting end of the index.
This commit is contained in:
Tom Lane
2010-01-01 21:53:49 +00:00
parent 15faca2596
commit 29c4ad9829
18 changed files with 295 additions and 120 deletions
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3
src/include/optimizer/planmain.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/planmain.h,v 1.121 2009/10/26 02:26:45 tgl Exp $
* $PostgreSQL: pgsql/src/include/optimizer/planmain.h,v 1.122 2010/01/01 21:53:49 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -39,6 +39,7 @@ extern Plan *optimize_minmax_aggregates(PlannerInfo *root, List *tlist,
* prototypes for plan/createplan.c
*/
extern Plan *create_plan(PlannerInfo *root, Path *best_path);
extern Node *fix_indexqual_operand(Node *node, IndexOptInfo *index);
extern SubqueryScan *make_subqueryscan(List *qptlist, List *qpqual,
Index scanrelid, Plan *subplan,
List *subrtable, List *subrowmark);