database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-11-06 07:49:08 +03:00
Code Activity

Revise implementation of SubLinks so that there is a consistent,

Browse Source 
documented intepretation of the lefthand and oper fields.  Fix a number of
obscure problems while at it --- for example, the old code failed if the parser
decided to insert a type-coercion function just below the operator of a
SubLink.
CAUTION: this will break stored rules that contain subplans.  You may
need to initdb.
This commit is contained in:
Tom Lane
1999-08-25 23:21:43 +00:00
parent edda70c0de
commit 42af56e1ea
8 changed files with 326 additions and 322 deletions
Download Patch File Download Diff File Expand all files Collapse all files

53
src/backend/optimizer/util/clauses.c
View File

@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.48 1999/08/22 20:14:53 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.49 1999/08/25 23:21:41 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@@ -817,8 +817,8 @@ CommuteClause(Expr *clause)
* the args and slink->oper lists (which belong to the outer plan), but it
* will *not* visit the inner plan, since that's typically what expression
* tree walkers want. A walker that wants to visit the subplan can force
* appropriate behavior by recognizing subplan nodes and doing the right
* thing.
* appropriate behavior by recognizing subplan expression nodes and doing
* the right thing.
*
* Bare SubLink nodes (without a SUBPLAN_EXPR) are handled by recursing into
* the "lefthand" argument list only. (A bare SubLink should be seen only if
@@ -854,26 +854,18 @@ expression_tree_walker(Node *node, bool (*walker) (), void *context)
case T_Expr:
{
Expr *expr = (Expr *) node;
if (expr->opType == SUBPLAN_EXPR)
{
/* examine args list (params to be passed to subplan) */
if (expression_tree_walker((Node *) expr->args,
walker, context))
return true;
/* examine oper list as well */
if (expression_tree_walker(
(Node *) ((SubPlan *) expr->oper)->sublink->oper,
walker, context))
return true;
/* but not the subplan itself */
}
else
{
/* for other Expr node types, just examine args list */
if (expression_tree_walker((Node *) expr->args,
walker, context))
/* recurse to the SubLink node (skipping SubPlan!) */
if (walker((Node *) ((SubPlan *) expr->oper)->sublink,
context))
return true;
}
/* for all Expr node types, examine args list */
if (expression_tree_walker((Node *) expr->args,
walker, context))
return true;
}
break;
case T_Aggref:
@@ -918,11 +910,20 @@ expression_tree_walker(Node *node, bool (*walker) (), void *context)
}
break;
case T_SubLink:
/* A "bare" SubLink (note we will not come here if we found
* a SUBPLAN_EXPR node above it). Examine the lefthand side,
* but not the oper list nor the subquery.
*/
return walker(((SubLink *) node)->lefthand, context);
{
SubLink *sublink = (SubLink *) node;
/* If the SubLink has already been processed by subselect.c,
* it will have lefthand=NIL, and we only need to look at
* the oper list. Otherwise we only need to look at lefthand
* (the Oper nodes in the oper list are deemed uninteresting).
*/
if (sublink->lefthand)
return walker((Node *) sublink->lefthand, context);
else
return walker((Node *) sublink->oper, context);
}
break;
case T_List:
foreach(temp, (List *) node)
{
@@ -988,8 +989,8 @@ expression_tree_walker(Node *node, bool (*walker) (), void *context)
* the args and slink->oper lists (which belong to the outer plan), but it
* will simply copy the link to the inner plan, since that's typically what
* expression tree mutators want. A mutator that wants to modify the subplan
* can force appropriate behavior by recognizing subplan nodes and doing the
* right thing.
* can force appropriate behavior by recognizing subplan expression nodes
* and doing the right thing.
*
* Bare SubLink nodes (without a SUBPLAN_EXPR) are handled by recursing into
* the "lefthand" argument list only. (A bare SubLink should be seen only if