switch s3Select.Output.format {
	case csvFormat:
		// Use bufio Writer to prevent csv.Writer from allocating a new buffer.
		bufioWriter := bufioWriterPool.Get().(*bufio.Writer)
		defer func() {
			bufioWriter.Reset(xioutil.Discard)
			bufioWriterPool.Put(bufioWriter)
		}()

		bufioWriter.Reset(buf)
		opts := sql.WriteCSVOpts{
			FieldDelimiter: []rune(s3Select.Output.CSVArgs.FieldDelimiter)[0],