*: Address comment

YEXINGZHE54 · Jan 23, 2016 · 7aa2791 · 7aa2791
1 parent 6ed674f
commit 7aa2791
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Showing 2 changed files with 5 additions and 3 deletions.
diff --git a/ast/functions.go b/ast/functions.go
@@ -557,7 +557,9 @@ func (n *AggregateFuncExpr) updateGroupConcat() error {
 			return nil
 		}
 	}
-	if ctx.Buffer.Len() > 0 {
+	if ctx.Buffer == nil {
+		ctx.Buffer = &bytes.Buffer{}
+	} else {
 		// now use comma separator
 		ctx.Buffer.WriteString(",")
 	}
@@ -621,6 +623,6 @@ type AggEvaluateContext struct {
 	distinctChecker *distinct.Checker
 	Count           int64
 	Value           interface{}
-	Buffer          bytes.Buffer // Buffer is used for group_concat.
+	Buffer          *bytes.Buffer // Buffer is used for group_concat.
 	evaluated       bool
 }
diff --git a/optimizer/evaluator/evaluator.go b/optimizer/evaluator/evaluator.go
@@ -991,7 +991,7 @@ func (e *Evaluator) evalAggAvg(v *ast.AggregateFuncExpr) {
 
 func (e *Evaluator) evalAggGroupConcat(v *ast.AggregateFuncExpr) {
 	ctx := v.GetContext()
-	if ctx.Buffer.Len() > 0 {
+	if ctx.Buffer != nil {
 		v.SetValue(ctx.Buffer.String())
 	} else {
 		v.SetValue(nil)