// Wait until the `start` go-routine is done.
		<-writer.doneCh
		return nil
	}
}

// newMessageWriter creates a message writer that writes to the HTTP
// response writer
func newMessageWriter(w http.ResponseWriter, getProgressFunc func() (bytesScanned, bytesProcessed int64)) *messageWriter {
	writer := &messageWriter{
		writer:          w,

func (s3Select *S3Select) Evaluate(w http.ResponseWriter) {
	getProgressFunc := s3Select.getProgress
	if !s3Select.Progress.Enabled {
		getProgressFunc = nil
	}
	writer := newMessageWriter(w, getProgressFunc)

	var outputQueue []sql.Record

	// Create queue based on the type.
	if s3Select.statement.IsAggregated() {
		outputQueue = make([]sql.Record, 0, 1)
	} else {