1 files changed, 11 insertions, 17 deletions

diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c
index 324356ec757..8b294378936 100644
--- a/src/backend/executor/nodeIndexscan.c
+++ b/src/backend/executor/nodeIndexscan.c
@@ -1332,12 +1332,12 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index,
 		{
 			/* (indexkey, indexkey, ...) op (expression, expression, ...) */
 			RowCompareExpr *rc = (RowCompareExpr *) clause;
-			ListCell   *largs_cell = list_head(rc->largs);
-			ListCell   *rargs_cell = list_head(rc->rargs);
-			ListCell   *opnos_cell = list_head(rc->opnos);
-			ListCell   *collids_cell = list_head(rc->inputcollids);
 			ScanKey		first_sub_key;
 			int			n_sub_key;
+			ListCell   *largs_cell;
+			ListCell   *rargs_cell;
+			ListCell   *opnos_cell;
+			ListCell   *collids_cell;
 
 			Assert(!isorderby);
 
@@ -1346,19 +1346,22 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index,
 			n_sub_key = 0;
 
 			/* Scan RowCompare columns and generate subsidiary ScanKey items */
-			while (opnos_cell != NULL)
+			forfour(largs_cell, rc->largs, rargs_cell, rc->rargs,
+					opnos_cell, rc->opnos, collids_cell, rc->inputcollids)
 			{
 				ScanKey		this_sub_key = &first_sub_key[n_sub_key];
 				int			flags = SK_ROW_MEMBER;
 				Datum		scanvalue;
 				Oid			inputcollation;
 
+				leftop = (Expr *) lfirst(largs_cell);
+				rightop = (Expr *) lfirst(rargs_cell);
+				opno = lfirst_oid(opnos_cell);
+				inputcollation = lfirst_oid(collids_cell);
+
 				/*
 				 * leftop should be the index key Var, possibly relabeled
 				 */
-				leftop = (Expr *) lfirst(largs_cell);
-				largs_cell = lnext(largs_cell);
-
 				if (leftop && IsA(leftop, RelabelType))
 					leftop = ((RelabelType *) leftop)->arg;
 
@@ -1374,9 +1377,6 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index,
 				 * We have to look up the operator's associated btree support
 				 * function
 				 */
-				opno = lfirst_oid(opnos_cell);
-				opnos_cell = lnext(opnos_cell);
-
 				if (index->rd_rel->relam != BTREE_AM_OID ||
 					varattno < 1 || varattno > indnkeyatts)
 					elog(ERROR, "bogus RowCompare index qualification");
@@ -1398,15 +1398,9 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index,
 					elog(ERROR, "missing support function %d(%u,%u) in opfamily %u",
 						 BTORDER_PROC, op_lefttype, op_righttype, opfamily);
 
-				inputcollation = lfirst_oid(collids_cell);
-				collids_cell = lnext(collids_cell);
-
 				/*
 				 * rightop is the constant or variable comparison value
 				 */
-				rightop = (Expr *) lfirst(rargs_cell);
-				rargs_cell = lnext(rargs_cell);
-
 				if (rightop && IsA(rightop, RelabelType))
 					rightop = ((RelabelType *) rightop)->arg;