Backport 12634 (vitessio#12680)

Signed-off-by: Florent Poinsard <florent.poinsard@outlook.fr>

Author: frouioui

go/vt/vtgate/planbuilder/physical/operator_funcs.go

@@ -231,11 +231,10 @@ func PushOutputColumns(ctx *plancontext.PlanningContext, op abstract.PhysicalOpe
 			var pos int
 			op.ColumnsOffset, pos = addToIntSlice(op.ColumnsOffset, i)
 			offsets = append(offsets, pos)
-			// skip adding to columns as it exists already.
+			op.Columns = append(op.Columns, col)
 			if i > -1 {
 				continue
 			}
-			op.Columns = append(op.Columns, col)
 			noQualifierNames = append(noQualifierNames, sqlparser.NewColName(col.Name.String()))
 		}
 		if len(noQualifierNames) > 0 {

go/vt/vtgate/planbuilder/testdata/systemtables_cases57.json

@@ -1287,7 +1287,7 @@
       "Instructions": {
         "OperatorType": "Join",
         "Variant": "Join",
-        "JoinColumnIndexes": "L:0",
+        "JoinColumnIndexes": "L:1",
         "JoinVars": {
           "x_COLUMN_NAME": 0
         },
@@ -1300,8 +1300,8 @@
               "Name": "main",
               "Sharded": false
             },
-            "FieldQuery": "select x.table_name from (select a.CONSTRAINT_CATALOG, a.CONSTRAINT_SCHEMA, a.CONSTRAINT_NAME, a.TABLE_CATALOG, a.TABLE_SCHEMA, a.TABLE_NAME, a.COLUMN_NAME, a.ORDINAL_POSITION, a.POSITION_IN_UNIQUE_CONSTRAINT, a.REFERENCED_TABLE_SCHEMA, a.REFERENCED_TABLE_NAME, a.REFERENCED_COLUMN_NAME from information_schema.key_column_usage as a where 1 != 1) as x where 1 != 1",
-            "Query": "select x.table_name from (select a.CONSTRAINT_CATALOG, a.CONSTRAINT_SCHEMA, a.CONSTRAINT_NAME, a.TABLE_CATALOG, a.TABLE_SCHEMA, a.TABLE_NAME, a.COLUMN_NAME, a.ORDINAL_POSITION, a.POSITION_IN_UNIQUE_CONSTRAINT, a.REFERENCED_TABLE_SCHEMA, a.REFERENCED_TABLE_NAME, a.REFERENCED_COLUMN_NAME from information_schema.key_column_usage as a) as x",
+            "FieldQuery": "select x.COLUMN_NAME, x.table_name from (select a.CONSTRAINT_CATALOG, a.CONSTRAINT_SCHEMA, a.CONSTRAINT_NAME, a.TABLE_CATALOG, a.TABLE_SCHEMA, a.TABLE_NAME, a.COLUMN_NAME, a.ORDINAL_POSITION, a.POSITION_IN_UNIQUE_CONSTRAINT, a.REFERENCED_TABLE_SCHEMA, a.REFERENCED_TABLE_NAME, a.REFERENCED_COLUMN_NAME from information_schema.key_column_usage as a where 1 != 1) as x where 1 != 1",
+            "Query": "select x.COLUMN_NAME, x.table_name from (select a.CONSTRAINT_CATALOG, a.CONSTRAINT_SCHEMA, a.CONSTRAINT_NAME, a.TABLE_CATALOG, a.TABLE_SCHEMA, a.TABLE_NAME, a.COLUMN_NAME, a.ORDINAL_POSITION, a.POSITION_IN_UNIQUE_CONSTRAINT, a.REFERENCED_TABLE_SCHEMA, a.REFERENCED_TABLE_NAME, a.REFERENCED_COLUMN_NAME from information_schema.key_column_usage as a) as x",
             "Table": "information_schema.key_column_usage"
           },
           {