According to the manualof RowDescription message
https://www.postgresql.org/docs/12/protocol-message-formats.html
Specifies the number of fields in a row (can be zero).
Does 0 fields could actually happen?
Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp