Get rid of the rather fuzzily defined FlattenedSubLink node type in favor of

making pull_up_sublinks() construct a full-blown JoinExpr tree representation
of IN/EXISTS SubLinks that it is able to convert to semi or anti joins.
This makes pull_up_sublinks() a shade more complex, but the gain in semantic
clarity is worth it.  I still have more to do in this area to address the
previously-discussed problems, but this commit in itself fixes at least one
bug in HEAD, as shown by added regression test case.

2 files changed, 2 insertions, 56 deletions

diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 65c9b614584..c9c7270d2b8 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.275 2009/01/09 15:46:10 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.276 2009/02/25 03:30:37 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -1300,15 +1300,6 @@ find_nonnullable_rels_walker(Node *node, bool top_level)
 			 expr->booltesttype == IS_NOT_UNKNOWN))
 			result = find_nonnullable_rels_walker((Node *) expr->arg, false);
 	}
-	else if (IsA(node, FlattenedSubLink))
-	{
-		/* JOIN_SEMI sublinks preserve strictness, but JOIN_ANTI ones don't */
-		FlattenedSubLink *expr = (FlattenedSubLink *) node;
-
-		if (expr->jointype == JOIN_SEMI)
-			result = find_nonnullable_rels_walker((Node *) expr->quals,
-												  top_level);
-	}
 	else if (IsA(node, PlaceHolderVar))
 	{
 		PlaceHolderVar *phv = (PlaceHolderVar *) node;
@@ -1511,15 +1502,6 @@ find_nonnullable_vars_walker(Node *node, bool top_level)
 			 expr->booltesttype == IS_NOT_UNKNOWN))
 			result = find_nonnullable_vars_walker((Node *) expr->arg, false);
 	}
-	else if (IsA(node, FlattenedSubLink))
-	{
-		/* JOIN_SEMI sublinks preserve strictness, but JOIN_ANTI ones don't */
-		FlattenedSubLink *expr = (FlattenedSubLink *) node;
-
-		if (expr->jointype == JOIN_SEMI)
-			result = find_nonnullable_vars_walker((Node *) expr->quals,
-												  top_level);
-	}
 	else if (IsA(node, PlaceHolderVar))
 	{
 		PlaceHolderVar *phv = (PlaceHolderVar *) node;
@@ -2943,24 +2925,6 @@ eval_const_expressions_mutator(Node *node,
 		newbtest->booltesttype = btest->booltesttype;
 		return (Node *) newbtest;
 	}
-	if (IsA(node, FlattenedSubLink))
-	{
-		FlattenedSubLink *fslink = (FlattenedSubLink *) node;
-		FlattenedSubLink *newfslink;
-		Expr	   *quals;
-
-		/* Simplify and also canonicalize the arguments */
-		quals = (Expr *) eval_const_expressions_mutator((Node *) fslink->quals,
-														context);
-		quals = canonicalize_qual(quals);
-
-		newfslink = makeNode(FlattenedSubLink);
-		newfslink->jointype = fslink->jointype;
-		newfslink->lefthand = fslink->lefthand;
-		newfslink->righthand = fslink->righthand;
-		newfslink->quals = quals;
-		return (Node *) newfslink;
-	}
 	if (IsA(node, PlaceHolderVar) && context->estimate)
 	{
 		/*
diff --git a/src/backend/optimizer/util/var.c b/src/backend/optimizer/util/var.c
index 64d6bba1480..7768712b569 100644
--- a/src/backend/optimizer/util/var.c
+++ b/src/backend/optimizer/util/var.c
@@ -14,7 +14,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/var.c,v 1.83 2009/01/01 17:23:45 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/var.c,v 1.84 2009/02/25 03:30:37 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -766,24 +766,6 @@ flatten_join_alias_vars_mutator(Node *node,
 		/* Recurse in case join input is itself a join */
 		return flatten_join_alias_vars_mutator(newvar, context);
 	}
-	if (IsA(node, FlattenedSubLink))
-	{
-		/* Copy the FlattenedSubLink node with correct mutation of subnodes */
-		FlattenedSubLink *fslink;
-
-		fslink = (FlattenedSubLink *) expression_tree_mutator(node,
-											 flatten_join_alias_vars_mutator,
-															 (void *) context);
-		/* now fix FlattenedSubLink's relid sets */
-		if (context->sublevels_up == 0)
-		{
-			fslink->lefthand = alias_relid_set(context->root,
-											   fslink->lefthand);
-			fslink->righthand = alias_relid_set(context->root,
-												fslink->righthand);
-		}
-		return (Node *) fslink;
-	}
 	if (IsA(node, PlaceHolderVar))
 	{
 		/* Copy the PlaceHolderVar node with correct mutation of subnodes */