Our protocol doc describes protocol negotiation message will send latest
minor version. However that field is a 4-byte one. The actual
implementation sends full version including the major part:
static void
SendNegotiateProtocolVersion(List *unrecognized_protocol_options)
{
StringInfoData buf;
ListCell *lc;
pq_beginmessage(&buf, PqMsg_NegotiateProtocolVersion);
pq_sendint32(&buf, FrontendProtocol);
pq_sendint32(&buf, list_length(unrecognized_protocol_options));
foreach(lc, unrecognized_protocol_options)
pq_sendstring(&buf, lfirst(lc));
pq_endmessage(&buf);
/* no need to flush, some other message will follow */
}
The patch included just clarifies this behavior by removing "minor" from
"newest minor version".
From 1bb00e792fbefa1dcf6e72fddb7baac1400c4dee Mon Sep 17 00:00:00 2001
From: Ning Sun <[email protected]>
Date: Sat, 6 Jun 2026 18:51:59 -0700
Subject: [PATCH] Protocol negotiation sends full version instead of minor
---
doc/src/sgml/protocol.sgml | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml
index 49f81676712..87dbc09af07 100644
--- a/doc/src/sgml/protocol.sgml
+++ b/doc/src/sgml/protocol.sgml
@@ -602,8 +602,8 @@
<para>
The server does not support the minor protocol version requested
by the client, but does support an earlier version of the protocol;
- this message indicates the highest supported minor version. This
- message will also be sent if the client requested unsupported protocol
+ this message indicates the highest supported version. This message
+ will also be sent if the client requested unsupported protocol
options (i.e., beginning with <literal>_pq_.</literal>) in the
startup packet.
</para>
@@ -5450,8 +5450,8 @@ psql "dbname=postgres replication=database" -c "IDENTIFY_SYSTEM;"
<term>Int32</term>
<listitem>
<para>
- Newest minor protocol version supported by the server
- for the major protocol version requested by the client.
+ Newest protocol version supported by the server for the
+ major protocol version requested by the client.
</para>
</listitem>
</varlistentry>
--
2.54.0
