diff --git a/dbcon/mysql/ha_calpont_execplan.cpp b/dbcon/mysql/ha_calpont_execplan.cpp
index 5ea8088d4..87c985f60 100755
--- a/dbcon/mysql/ha_calpont_execplan.cpp
+++ b/dbcon/mysql/ha_calpont_execplan.cpp
@@ -3546,6 +3546,10 @@ ReturnedColumn* buildAggregateColumn(Item* item, gp_walk_info& gwi)
 					if (ac->aggOp() == AggregateColumn::COUNT)
 						ac->aggOp(AggregateColumn::COUNT_ASTERISK);
 
+                    // MCOL-301: treat SUM(1) as MAX(1) to get constant result
+                    if (ac->aggOp() == AggregateColumn::SUM)
+                        ac->aggOp(AggregateColumn::MAX);
+
 					ac->constCol(SRCP(buildReturnedColumn(sfitemp, gwi, gwi.fatalParseError)));
 					break;
 				}
@@ -3584,6 +3588,10 @@ ReturnedColumn* buildAggregateColumn(Item* item, gp_walk_info& gwi)
 							ReturnedColumn* rc = buildReturnedColumn(sfitemp, gwi, gwi.fatalParseError);
 							if (dynamic_cast<ConstantColumn*>(rc))
 							{
+                                // MCOL-301: treat SUM(1) as MAX(1) to get constant result
+                                if (ac->aggOp() == AggregateColumn::SUM)
+                                    ac->aggOp(AggregateColumn::MAX);
+
 								//@bug5229. handle constant function on aggregate argument
 								ac->constCol(SRCP(rc));
 								break;