1 files changed, 25 insertions, 14 deletions

diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 317c10c2b9f..33790a4f463 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -31,6 +31,7 @@
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "nodes/makefuncs.h"
+#include "nodes/multibitmapset.h"
 #include "nodes/nodeFuncs.h"
 #include "nodes/subscripting.h"
 #include "nodes/supportnodes.h"
@@ -1566,7 +1567,7 @@ find_nonnullable_rels_walker(Node *node, bool top_level)
  * find_nonnullable_vars
  *		Determine which Vars are forced nonnullable by given clause.
  *
- * Returns a list of all level-zero Vars that are referenced in the clause in
+ * Returns the set of all level-zero Vars that are referenced in the clause in
  * such a way that the clause cannot possibly return TRUE if any of these Vars
  * is NULL.  (It is OK to err on the side of conservatism; hence the analysis
  * here is simplistic.)
@@ -1578,8 +1579,9 @@ find_nonnullable_rels_walker(Node *node, bool top_level)
  * the expression to have been AND/OR flattened and converted to implicit-AND
  * format.
  *
- * The result is a palloc'd List, but we have not copied the member Var nodes.
- * Also, we don't bother trying to eliminate duplicate entries.
+ * Attnos of the identified Vars are returned in a multibitmapset (a List of
+ * Bitmapsets).  List indexes correspond to relids (varnos), while the per-rel
+ * Bitmapsets hold varattnos offset by FirstLowInvalidHeapAttributeNumber.
  *
  * top_level is true while scanning top-level AND/OR structure; here, showing
  * the result is either FALSE or NULL is good enough.  top_level is false when
@@ -1608,7 +1610,9 @@ find_nonnullable_vars_walker(Node *node, bool top_level)
 		Var		   *var = (Var *) node;
 
 		if (var->varlevelsup == 0)
-			result = list_make1(var);
+			result = mbms_add_member(result,
+									 var->varno,
+									 var->varattno - FirstLowInvalidHeapAttributeNumber);
 	}
 	else if (IsA(node, List))
 	{
@@ -1623,9 +1627,9 @@ find_nonnullable_vars_walker(Node *node, bool top_level)
 		 */
 		foreach(l, (List *) node)
 		{
-			result = list_concat(result,
-								 find_nonnullable_vars_walker(lfirst(l),
-															  top_level));
+			result = mbms_add_members(result,
+									  find_nonnullable_vars_walker(lfirst(l),
+																   top_level));
 		}
 	}
 	else if (IsA(node, FuncExpr))
@@ -1657,7 +1661,12 @@ find_nonnullable_vars_walker(Node *node, bool top_level)
 		switch (expr->boolop)
 		{
 			case AND_EXPR:
-				/* At top level we can just recurse (to the List case) */
+
+				/*
+				 * At top level we can just recurse (to the List case), since
+				 * the result should be the union of what we can prove in each
+				 * arm.
+				 */
 				if (top_level)
 				{
 					result = find_nonnullable_vars_walker((Node *) expr->args,
@@ -1689,7 +1698,7 @@ find_nonnullable_vars_walker(Node *node, bool top_level)
 					if (result == NIL)	/* first subresult? */
 						result = subresult;
 					else
-						result = list_intersection(result, subresult);
+						result = mbms_int_members(result, subresult);
 
 					/*
 					 * If the intersection is empty, we can stop looking. This
@@ -1788,8 +1797,8 @@ find_nonnullable_vars_walker(Node *node, bool top_level)
  * side of conservatism; hence the analysis here is simplistic.  In fact,
  * we only detect simple "var IS NULL" tests at the top level.)
  *
- * The result is a palloc'd List, but we have not copied the member Var nodes.
- * Also, we don't bother trying to eliminate duplicate entries.
+ * As with find_nonnullable_vars, we return the varattnos of the identified
+ * Vars in a multibitmapset.
  */
 List *
 find_forced_null_vars(Node *node)
@@ -1804,7 +1813,9 @@ find_forced_null_vars(Node *node)
 	var = find_forced_null_var(node);
 	if (var)
 	{
-		result = list_make1(var);
+		result = mbms_add_member(result,
+								 var->varno,
+								 var->varattno - FirstLowInvalidHeapAttributeNumber);
 	}
 	/* Otherwise, handle AND-conditions */
 	else if (IsA(node, List))
@@ -1815,8 +1826,8 @@ find_forced_null_vars(Node *node)
 		 */
 		foreach(l, (List *) node)
 		{
-			result = list_concat(result,
-								 find_forced_null_vars(lfirst(l)));
+			result = mbms_add_members(result,
+									  find_forced_null_vars((Node *) lfirst(l)));
 		}
 	}
 	else if (IsA(node, BoolExpr))