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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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12
src/backend/optimizer/plan/createplan.c
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@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.268 2009/12/29 20:11:45 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.269 2010/01/01 21:53:49 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -73,7 +73,6 @@ static MergeJoin *create_mergejoin_plan(PlannerInfo *root, MergePath *best_path,
static HashJoin *create_hashjoin_plan(PlannerInfo *root, HashPath *best_path,
Plan *outer_plan, Plan *inner_plan);
static List *fix_indexqual_references(List *indexquals, IndexPath *index_path);
static Node *fix_indexqual_operand(Node *node, IndexOptInfo *index);
static List *get_switched_clauses(List *clauses, Relids outerrelids);
static List *order_qual_clauses(PlannerInfo *root, List *clauses);
static void copy_path_costsize(Plan *dest, Path *src);
@ -2117,7 +2116,6 @@ fix_indexqual_references(List *indexquals, IndexPath *index_path)
{
NullTest *nt = (NullTest *) clause;
Assert(nt->nulltesttype == IS_NULL);
nt->arg = (Expr *) fix_indexqual_operand((Node *) nt->arg,
index);
}
@ -2131,7 +2129,13 @@ fix_indexqual_references(List *indexquals, IndexPath *index_path)
return fixed_indexquals;
}
static Node *
/*
* fix_indexqual_operand
* Convert an indexqual expression to a Var referencing the index column.
*
* This is exported because planagg.c needs it.
*/
Node *
fix_indexqual_operand(Node *node, IndexOptInfo *index)
{
/*