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First cut at doing something reasonable with OR-of-ANDs WHERE

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conditions.  There are some pretty bogus heuristics in prepqual.c that
try to decide whether to output CNF or DNF format; they need to be replaced,
likely.  Right now the code is probably too willing to choose DNF form,
which might hurt performance in some cases that used to work OK.
But at least we have a foundation to build on.
This commit is contained in:
Tom Lane
1999-09-13 00:17:25 +00:00
parent b705fa3909
commit 43d32d3683
5 changed files with 269 additions and 21 deletions
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44
src/backend/optimizer/path/indxpath.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.70 1999/08/21 03:49:00 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.71 1999/09/13 00:17:19 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -48,6 +48,9 @@ static void match_index_orclauses(RelOptInfo *rel, RelOptInfo *index, int indexk
int xclass, List *restrictinfo_list);
static List *match_index_orclause(RelOptInfo *rel, RelOptInfo *index, int indexkey,
int xclass, List *or_clauses, List *other_matching_indices);
static bool match_or_subclause_to_indexkey(RelOptInfo *rel, RelOptInfo *index,
int indexkey, int xclass,
Expr *clause);
static List *group_clauses_by_indexkey(RelOptInfo *rel, RelOptInfo *index,
int *indexkeys, Oid *classes, List *restrictinfo_list);
static List *group_clauses_by_ikey_for_joins(RelOptInfo *rel, RelOptInfo *index,
@ -327,8 +330,8 @@ match_index_orclause(RelOptInfo *rel,
{
Expr *clause = lfirst(clist);
if (match_clause_to_indexkey(rel, index, indexkey, xclass,
clause, false))
if (match_or_subclause_to_indexkey(rel, index, indexkey, xclass,
clause))
{
/* OK to add this index to sublist for this subclause */
lfirst(matching_indices) = lcons(index,
@ -341,6 +344,38 @@ match_index_orclause(RelOptInfo *rel,
return index_list;
}
/*
* See if a subclause of an OR clause matches an index.
*
* We accept the subclause if it is an operator clause that matches the
* index, or if it is an AND clause all of whose members are operators
* that match the index. (XXX Would accepting a single match be useful?)
*/
static bool
match_or_subclause_to_indexkey(RelOptInfo *rel,
RelOptInfo *index,
int indexkey,
int xclass,
Expr *clause)
{
if (and_clause((Node *) clause))
{
List *item;
foreach(item, clause->args)
{
if (! match_clause_to_indexkey(rel, index, indexkey, xclass,
lfirst(item), false))
return false;
}
return true;
}
else
return match_clause_to_indexkey(rel, index, indexkey, xclass,
clause, false);
}
/****************************************************************************
* ---- ROUTINES TO CHECK RESTRICTIONS ----
****************************************************************************/
@ -559,7 +594,8 @@ group_clauses_by_ikey_for_joins(RelOptInfo *rel,
*
* Returns true if the clause can be used with this index key.
*
* NOTE: returns false if clause is an or_clause; that's handled elsewhere.
* NOTE: returns false if clause is an OR or AND clause; to the extent
* we cope with those at all, it is done by higher-level routines.
*/
static bool
match_clause_to_indexkey(RelOptInfo *rel,