add check for canOrdering. Fix for current opclasses follows

Author: feodor

Diff for: src/rumscan.c

@@ -164,30 +164,37 @@ rumFillScanKey(RumScanOpaque so, OffsetNumber attnum,
 	key->addInfoKeys = NULL;
 	key->addInfoNKeys = 0;
 
-	if (key->orderBy && key->attnum == rumstate->attrnAttachColumn)
+	if (key->orderBy)
 	{
-		if (nQueryValues != 1)
-			elog(ERROR, "extractQuery should return only one value for ordering");
-		if (rumstate->canOuterOrdering[attnum - 1] == false)
-			elog(ERROR, "doesn't support ordering as additional info");
-		if (rumstate->origTupdesc->attrs[rumstate->attrnAttachColumn - 1]->attbyval == false)
-			elog(ERROR, "doesn't support order by over pass-by-reference column");
+		if (key->attnum == rumstate->attrnAttachColumn)
+		{
+			if (nQueryValues != 1)
+				elog(ERROR, "extractQuery should return only one value for ordering");
+			if (rumstate->canOuterOrdering[attnum - 1] == false)
+				elog(ERROR, "doesn't support ordering as additional info");
+			if (rumstate->origTupdesc->attrs[rumstate->attrnAttachColumn - 1]->attbyval == false)
+				elog(ERROR, "doesn't support order by over pass-by-reference column");
 
-		key->useAddToColumn = true;
-		key->attnum = rumstate->attrnAddToColumn;
-		key->nentries = 0;
-		key->nuserentries = 0;
+			key->useAddToColumn = true;
+			key->attnum = rumstate->attrnAddToColumn;
+			key->nentries = 0;
+			key->nuserentries = 0;
 
-		key->outerAddInfoIsNull = true;
+			key->outerAddInfoIsNull = true;
 
-		key->scanEntry = NULL;
-		key->entryRes = NULL;
-		key->addInfo = NULL;
-		key->addInfoIsNull = NULL;
+			key->scanEntry = NULL;
+			key->entryRes = NULL;
+			key->addInfo = NULL;
+			key->addInfoIsNull = NULL;
 
-		so->willSort = true;
+			so->willSort = true;
 
-		return;
+			return;
+		}
+		else if (rumstate->canOrdering[attnum - 1] == false)
+		{
+			elog(ERROR,"doesn't support ordering, check operator class definition");
+		}
 	}
 
 	key->nentries = nQueryValues;