feat: add a constant to store the group concat default separator

Signed-off-by: Manan Gupta <[email protected]>

.gitignore

@@ -56,6 +56,8 @@ __debug_bin
 /php/composer.phar
 /php/vendor
 
+report*.xml
+
 # vitess.io preview site
 /preview-vitess.io/
 

go/vt/sqlparser/constants.go

@@ -478,6 +478,9 @@ const (
 	// KillType strings
 	ConnectionStr = "connection"
 	QueryStr      = "query"
+
+	// GroupConcatDefaultSeparator is the default separator for GroupConcatExpr.
+	GroupConcatDefaultSeparator = ","
 )
 
 // Constants for Enum Type - Insert.Action

go/vt/vtgate/planbuilder/operator_transformers.go

@@ -310,7 +310,7 @@ func transformAggregator(ctx *plancontext.PlanningContext, op *operators.Aggrega
 		aggrParam := engine.NewAggregateParam(aggr.OpCode, aggr.ColOffset, aggr.Alias, ctx.VSchema.Environment().CollationEnv())
 		aggrParam.Func = aggr.Func
 		if gcFunc, isGc := aggrParam.Func.(*sqlparser.GroupConcatExpr); isGc && gcFunc.Separator == "" {
-			gcFunc.Separator = ","
+			gcFunc.Separator = sqlparser.GroupConcatDefaultSeparator
 		}
 		aggrParam.Original = aggr.Original
 		aggrParam.OrigOpcode = aggr.OriginalOpCode