diff --git a/executor/builder.go b/executor/builder.go
index c1af39918e110..6651da0c90bf7 100644
--- a/executor/builder.go
+++ b/executor/builder.go
@@ -2231,7 +2231,7 @@ func (builder *dataReaderBuilder) buildProjectionForIndexJoin(ctx context.Contex
 	if int64(v.StatsCount()) < int64(builder.ctx.GetSessionVars().MaxChunkSize) {
 		e.numWorkers = 0
 	}
-	err = e.Open(ctx)
+	err = e.open(ctx)
 
 	return e, err
 }
diff --git a/executor/projection.go b/executor/projection.go
index e6423b03b2af8..70de60f3dab66 100644
--- a/executor/projection.go
+++ b/executor/projection.go
@@ -77,7 +77,10 @@ func (e *ProjectionExec) Open(ctx context.Context) error {
 	if err := e.baseExecutor.Open(ctx); err != nil {
 		return err
 	}
+	return e.open(ctx)
+}
 
+func (e *ProjectionExec) open(ctx context.Context) error {
 	e.prepared = false
 	e.parentReqRows = int64(e.maxChunkSize)