*** a/src/backend/optimizer/plan/planagg.c
--- b/src/backend/optimizer/plan/planagg.c
***************
*** 314,328 **** find_minmax_aggs_walker(Node *node, List **context)
  		ListCell   *l;
  
  		Assert(aggref->agglevelsup == 0);
! 		if (list_length(aggref->args) != 1 || aggref->aggorder != NIL)
  			return true;		/* it couldn't be MIN/MAX */
! 		/* note: we do not care if DISTINCT is mentioned ... */
! 		curTarget = (TargetEntry *) linitial(aggref->args);
  
  		aggsortop = fetch_agg_sort_op(aggref->aggfnoid);
  		if (!OidIsValid(aggsortop))
  			return true;		/* not a MIN/MAX aggregate */
  
  		if (contain_mutable_functions((Node *) curTarget->expr))
  			return true;		/* not potentially indexable */
  
--- 314,333 ----
  		ListCell   *l;
  
  		Assert(aggref->agglevelsup == 0);
! 		if (list_length(aggref->args) != 1)
  			return true;		/* it couldn't be MIN/MAX */
! 
! 		/*
! 		 * Ignore ORDER BY and DISTINCT, which are valid but pointless on
! 		 * MIN/MAX.  They do not change its result.
! 		 */
  
  		aggsortop = fetch_agg_sort_op(aggref->aggfnoid);
  		if (!OidIsValid(aggsortop))
  			return true;		/* not a MIN/MAX aggregate */
  
+ 		curTarget = (TargetEntry *) linitial(aggref->args);
+ 
  		if (contain_mutable_functions((Node *) curTarget->expr))
  			return true;		/* not potentially indexable */