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Reconsider mechanism for marking sub-selects that are at top level of

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a qualification clause (and hence can get away with being sloppy about
distinguishing FALSE from UNKNOWN).  We need to know this in subselect.c;
marking the subplans in setrefs.c is too late.
This commit is contained in:
Tom Lane
2003-01-13 18:10:53 +00:00
parent de432ce39e
commit 56e1aab286
4 changed files with 34 additions and 53 deletions
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42
src/backend/optimizer/plan/subselect.c
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@@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.65 2003/01/13 00:29:26 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.66 2003/01/13 18:10:53 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -65,7 +65,7 @@ static List *convert_sublink_opers(List *lefthand, List *operOids,
List *targetlist, List **paramIds);
static bool subplan_is_hashable(SubLink *slink, SubPlan *node);
static Node *replace_correlation_vars_mutator(Node *node, void *context);
static Node *process_sublinks_mutator(Node *node, void *context);
static Node *process_sublinks_mutator(Node *node, bool *isTopQual);
static bool finalize_primnode(Node *node, finalize_primnode_results *results);
@@ -159,7 +159,8 @@ generate_new_param(Oid paramtype, int32 paramtypmod)
* Convert a bare SubLink (as created by the parser) into a SubPlan.
*
* We are given the raw SubLink and the already-processed lefthand argument
* list (use this instead of the SubLink's own field).
* list (use this instead of the SubLink's own field). We are also told if
* this expression appears at top level of a WHERE/HAVING qual.
*
* The result is whatever we need to substitute in place of the SubLink
* node in the executable expression. This will be either the SubPlan
@@ -168,7 +169,7 @@ generate_new_param(Oid paramtype, int32 paramtypmod)
* containing InitPlan Param nodes.
*/
static Node *
make_subplan(SubLink *slink, List *lefthand)
make_subplan(SubLink *slink, List *lefthand, bool isTopQual)
{
SubPlan *node = makeNode(SubPlan);
Query *subquery = (Query *) (slink->subselect);
@@ -232,7 +233,8 @@ make_subplan(SubLink *slink, List *lefthand)
node->exprs = NIL;
node->paramIds = NIL;
node->useHashTable = false;
node->unknownEqFalse = false;
/* At top level of a qual, can treat UNKNOWN the same as FALSE */
node->unknownEqFalse = isTopQual;
node->setParam = NIL;
node->parParam = NIL;
node->args = NIL;
@@ -589,17 +591,23 @@ replace_correlation_vars_mutator(Node *node, void *context)
/*
* Expand SubLinks to SubPlans in the given expression.
*
* The isQual argument tells whether or not this expression is a WHERE/HAVING
* qualifier expression. If it is, any sublinks appearing at top level need
* not distinguish FALSE from UNKNOWN return values.
*/
Node *
SS_process_sublinks(Node *expr)
SS_process_sublinks(Node *expr, bool isQual)
{
/* No setup needed for tree walk, so away we go */
return process_sublinks_mutator(expr, NULL);
/* The only context needed is the initial are-we-in-a-qual flag */
return process_sublinks_mutator(expr, &isQual);
}
static Node *
process_sublinks_mutator(Node *node, void *context)
process_sublinks_mutator(Node *node, bool *isTopQual)
{
bool locTopQual;
if (node == NULL)
return NULL;
if (IsA(node, SubLink))
@@ -610,12 +618,13 @@ process_sublinks_mutator(Node *node, void *context)
/*
* First, recursively process the lefthand-side expressions, if any.
*/
locTopQual = false;
lefthand = (List *)
process_sublinks_mutator((Node *) sublink->lefthand, context);
process_sublinks_mutator((Node *) sublink->lefthand, &locTopQual);
/*
* Now build the SubPlan node and make the expr to return.
*/
return make_subplan(sublink, lefthand);
return make_subplan(sublink, lefthand, *isTopQual);
}
/*
@@ -626,9 +635,18 @@ process_sublinks_mutator(Node *node, void *context)
*/
Assert(!is_subplan(node));
/*
* If we recurse down through anything other than a List node, we are
* definitely not at top qual level anymore.
*/
if (IsA(node, List))
locTopQual = *isTopQual;
else
locTopQual = false;
return expression_tree_mutator(node,
process_sublinks_mutator,
context);
(void *) &locTopQual);
}
/*