*** plancat.c.orig	2007-04-30 12:17:55.785145396 -0400
--- plancat.c	2007-04-30 14:15:48.093639183 -0400
***************
*** 473,478 ****
--- 473,479 ----
  	List	   *constraint_pred;
  	List	   *safe_constraints;
  	ListCell   *lc;
+ 	bool	    found_unsafe_restrictions;
  
  	/* Skip the test if constraint exclusion is disabled */
  	if (!constraint_exclusion)
***************
*** 486,491 ****
--- 487,493 ----
  	 * Note: strip off RestrictInfo because predicate_refuted_by() isn't
  	 * expecting to see any in its predicate argument.
  	 */
+ 	found_unsafe_restrictions = false;
  	safe_restrictions = NIL;
  	foreach(lc, rel->baserestrictinfo)
  	{
***************
*** 493,498 ****
--- 495,502 ----
  
  		if (!contain_mutable_functions((Node *) rinfo->clause))
  			safe_restrictions = lappend(safe_restrictions, rinfo->clause);
+ 		else
+ 			found_unsafe_restrictions = true;
  	}
  
  	if (predicate_refuted_by(safe_restrictions, safe_restrictions))
***************
*** 522,527 ****
--- 526,559 ----
  	}
  
  	/*
+ 	 *  Check the restrictions against the relation constraints.
+ 	 *  If we found mutable functions in the restrictions, try to simplify
+ 	 *  them prior to checking.  Effectively, this folds stable and immutable
+ 	 *  functions into constant values.  
+ 	 */
+ 	if (found_unsafe_restrictions)
+ 	{
+ 		List * simp_restrictions = NIL;
+ 		foreach(lc, rel->baserestrictinfo)
+ 		{
+ 			RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
+ 			Node * baseNode = (Node *) rinfo->clause;
+ 
+ 			if (IsA(baseNode, FuncExpr) || IsA(baseNode, OpExpr))
+ 			{
+ 				Node * simpNode = estimate_expression_value(baseNode);
+ 				simp_restrictions = lappend(simp_restrictions, simpNode);
+ 			}
+ 			else
+ 			{
+ 				simp_restrictions = lappend(simp_restrictions, baseNode);
+ 			}
+ 		}
+ 
+ 		if (predicate_refuted_by(safe_constraints, simp_restrictions))
+ 			return true;
+ 	}
+ 	/*
  	 * The constraints are effectively ANDed together, so we can just try to
  	 * refute the entire collection at once.  This may allow us to make proofs
  	 * that would fail if we took them individually.
***************
*** 531,538 ****
  	 * have volatile and nonvolatile subclauses, and it's OK to make
  	 * deductions with the nonvolatile parts.
  	 */
! 	if (predicate_refuted_by(safe_constraints, rel->baserestrictinfo))
  		return true;
  
  	return false;
  }
--- 563,572 ----
  	 * have volatile and nonvolatile subclauses, and it's OK to make
  	 * deductions with the nonvolatile parts.
  	 */
! 	else if (predicate_refuted_by(safe_constraints, rel->baserestrictinfo))
! 	{
  		return true;
+ 	}
  
  	return false;
  }