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Refactor planner's pathkeys data structure to create a separate, explicit

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representation of equivalence classes of variables.  This is an extensive
rewrite, but it brings a number of benefits:
* planner no longer fails in the presence of "incomplete" operator families
that don't offer operators for every possible combination of datatypes.
* avoid generating and then discarding redundant equality clauses.
* remove bogus assumption that derived equalities always use operators
named "=".
* mergejoins can work with a variety of sort orders (e.g., descending) now,
instead of tying each mergejoinable operator to exactly one sort order.
* better recognition of redundant sort columns.
* can make use of equalities appearing underneath an outer join.
This commit is contained in:
Tom Lane
2007-01-20 20:45:41 +00:00
parent 2b7334d487
commit f41803bb39
35 changed files with 3882 additions and 2719 deletions
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42
src/backend/nodes/copyfuncs.c
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@ -15,7 +15,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.361 2007/01/10 18:06:02 tgl Exp $
* $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.362 2007/01/20 20:45:38 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1284,16 +1284,18 @@ _copyFromExpr(FromExpr *from)
*/
/*
* _copyPathKeyItem
* _copyPathKey
*/
static PathKeyItem *
_copyPathKeyItem(PathKeyItem *from)
static PathKey *
_copyPathKey(PathKey *from)
{
PathKeyItem *newnode = makeNode(PathKeyItem);
PathKey *newnode = makeNode(PathKey);
COPY_NODE_FIELD(key);
COPY_SCALAR_FIELD(sortop);
COPY_SCALAR_FIELD(nulls_first);
/* EquivalenceClasses are never moved, so just shallow-copy the pointer */
COPY_SCALAR_FIELD(pk_eclass);
COPY_SCALAR_FIELD(pk_opfamily);
COPY_SCALAR_FIELD(pk_strategy);
COPY_SCALAR_FIELD(pk_nulls_first);
return newnode;
}
@ -1316,21 +1318,15 @@ _copyRestrictInfo(RestrictInfo *from)
COPY_BITMAPSET_FIELD(left_relids);
COPY_BITMAPSET_FIELD(right_relids);
COPY_NODE_FIELD(orclause);
/* EquivalenceClasses are never copied, so shallow-copy the pointers */
COPY_SCALAR_FIELD(parent_ec);
COPY_SCALAR_FIELD(eval_cost);
COPY_SCALAR_FIELD(this_selec);
COPY_SCALAR_FIELD(mergejoinoperator);
COPY_SCALAR_FIELD(left_sortop);
COPY_SCALAR_FIELD(right_sortop);
COPY_SCALAR_FIELD(mergeopfamily);
/*
* Do not copy pathkeys, since they'd not be canonical in a copied query
*/
newnode->left_pathkey = NIL;
newnode->right_pathkey = NIL;
COPY_SCALAR_FIELD(left_mergescansel);
COPY_SCALAR_FIELD(right_mergescansel);
COPY_NODE_FIELD(mergeopfamilies);
/* EquivalenceClasses are never copied, so shallow-copy the pointers */
COPY_SCALAR_FIELD(left_ec);
COPY_SCALAR_FIELD(right_ec);
COPY_SCALAR_FIELD(outer_is_left);
COPY_SCALAR_FIELD(hashjoinoperator);
COPY_SCALAR_FIELD(left_bucketsize);
COPY_SCALAR_FIELD(right_bucketsize);
@ -3033,8 +3029,8 @@ copyObject(void *from)
/*
* RELATION NODES
*/
case T_PathKeyItem:
retval = _copyPathKeyItem(from);
case T_PathKey:
retval = _copyPathKey(from);
break;
case T_RestrictInfo:
retval = _copyRestrictInfo(from);