Fix extremely nasty little bug observed when a sub-SELECT appears in

WHERE in a place where it can be part of a nestloop inner indexqual.
As the code stood, it put the same physical sub-Plan node into both
indxqual and indxqualorig of the IndexScan plan node.  That confused
later processing in the optimizer (which expected that tracing the
subPlan list would visit each subplan node exactly once), and would
probably have blown up in the executor if the planner hadn't choked first.
Fix by making the 'fixed' indexqual be a complete deep copy of the
original indexqual, rather than trying to share nodes below the topmost
operator node.  This had further ramifications though, because we were
making the aforesaid list of sub-Plan nodes during SS_process_sublinks
which is run before construction of the 'fixed' indexqual, meaning that
the copy of the sub-Plan didn't show up in that list.  Fix by rearranging
logic so that the sub-Plan list is built by the final set_plan_references
pass, not in SS_process_sublinks.  This may sound like a mess, but it's
actually a good deal cleaner now than it was before, because we are no
longer dependent on the assumption that planning will never make a copy
of a sub-Plan node.

1 files changed, 103 insertions, 33 deletions

diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 8d4dae486ac..d429db93a03 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.63 2000/03/21 05:12:12 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.64 2000/04/04 01:21:46 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -43,6 +43,8 @@
 
 static bool contain_agg_clause_walker(Node *node, void *context);
 static bool pull_agg_clause_walker(Node *node, List **listptr);
+static bool contain_subplans_walker(Node *node, void *context);
+static bool pull_subplans_walker(Node *node, List **listptr);
 static bool check_subplans_for_ungrouped_vars_walker(Node *node,
 													 Query *context);
 static int is_single_func(Node *node);
@@ -358,39 +360,9 @@ make_ands_implicit(Expr *clause)
 
 
 /*****************************************************************************
- *																			 *
- *		General clause-manipulating routines								 *
- *																			 *
+ *		Aggregate-function clause manipulation
  *****************************************************************************/
 
-
-/*
- * pull_constant_clauses
- *	  Scans through a list of qualifications and find those that
- *	  contain no variables (of the current query level).
- *
- * Returns a list of the constant clauses in constantQual and the remaining
- * quals as the return value.
- *
- */
-List *
-pull_constant_clauses(List *quals, List **constantQual)
-{
-	List	   *q;
-	List	   *constqual = NIL;
-	List	   *restqual = NIL;
-
-	foreach(q, quals)
-	{
-		if (!contain_var_clause(lfirst(q)))
-			constqual = lcons(lfirst(q), constqual);
-		else
-			restqual = lcons(lfirst(q), restqual);
-	}
-	*constantQual = constqual;
-	return restqual;
-}
-
 /*
  * contain_agg_clause
  *	  Recursively search for Aggref nodes within a clause.
@@ -454,6 +426,68 @@ pull_agg_clause_walker(Node *node, List **listptr)
 								  (void *) listptr);
 }
 
+
+/*****************************************************************************
+ *		Subplan clause manipulation
+ *****************************************************************************/
+
+/*
+ * contain_subplans
+ *	  Recursively search for subplan nodes within a clause.
+ *
+ * If we see a SubLink node, we will return TRUE.  This is only possible if
+ * the expression tree hasn't yet been transformed by subselect.c.  We do not
+ * know whether the node will produce a true subplan or just an initplan,
+ * but we make the conservative assumption that it will be a subplan.
+ *
+ * Returns true if any subplan found.
+ */
+bool
+contain_subplans(Node *clause)
+{
+	return contain_subplans_walker(clause, NULL);
+}
+
+static bool
+contain_subplans_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+	if (is_subplan(node) || IsA(node, SubLink))
+		return true;			/* abort the tree traversal and return true */
+	return expression_tree_walker(node, contain_subplans_walker, context);
+}
+
+/*
+ * pull_subplans
+ *	  Recursively pulls all subplans from an expression tree.
+ *
+ *	  Returns list of subplan nodes found.  Note the nodes themselves are not
+ *	  copied, only referenced.
+ */
+List *
+pull_subplans(Node *clause)
+{
+	List	   *result = NIL;
+
+	pull_subplans_walker(clause, &result);
+	return result;
+}
+
+static bool
+pull_subplans_walker(Node *node, List **listptr)
+{
+	if (node == NULL)
+		return false;
+	if (is_subplan(node))
+	{
+		*listptr = lappend(*listptr, ((Expr *) node)->oper);
+		/* fall through to check args to subplan */
+	}
+	return expression_tree_walker(node, pull_subplans_walker,
+								  (void *) listptr);
+}
+
 /*
  * check_subplans_for_ungrouped_vars
  *		Check for subplans that are being passed ungrouped variables as
@@ -556,6 +590,41 @@ check_subplans_for_ungrouped_vars_walker(Node *node,
 }
 
 
+/*****************************************************************************
+ *																			 *
+ *		General clause-manipulating routines								 *
+ *																			 *
+ *****************************************************************************/
+
+
+/*
+ * pull_constant_clauses
+ *	  Scans through a list of qualifications and find those that
+ *	  contain no variables (of the current query level).
+ *
+ * Returns a list of the constant clauses in constantQual and the remaining
+ * quals as the return value.
+ *
+ */
+List *
+pull_constant_clauses(List *quals, List **constantQual)
+{
+	List	   *q;
+	List	   *constqual = NIL;
+	List	   *restqual = NIL;
+
+	foreach(q, quals)
+	{
+		if (!contain_var_clause(lfirst(q)))
+			constqual = lcons(lfirst(q), constqual);
+		else
+			restqual = lcons(lfirst(q), restqual);
+	}
+	*constantQual = constqual;
+	return restqual;
+}
+
+
 /*
  * clause_relids_vars
  *	  Retrieves distinct relids and vars appearing within a clause.
@@ -726,7 +795,8 @@ default_results:
  *   If the given expression is a function of a single relation,
  *   return the relation number; else return 0
  */
-static int is_single_func(Node *node)
+static int
+is_single_func(Node *node)
 {
 	if (is_funcclause(node))
 	{