diff options
| -rw-r--r-- | doc/src/sgml/protocol.sgml | 104 |
1 files changed, 79 insertions, 25 deletions
diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml index 4dab0cb4923..d73e4d6dbdf 100644 --- a/doc/src/sgml/protocol.sgml +++ b/doc/src/sgml/protocol.sgml @@ -22,31 +22,6 @@ <productname>PostgreSQL</productname> version 18. The server and the libpq client library are backwards compatible with protocol version 3.0, implemented in <productname>PostgreSQL</productname> 7.4 and later. - For descriptions of earlier protocol versions, see previous releases of the - <productname>PostgreSQL</productname> documentation. - </para> - - <para> - A single server - can support multiple protocol versions. The initial startup-request - message tells the server which protocol version the client is attempting to - use. If the major version requested by the client is not supported by - the server, the connection will be rejected (for example, this would occur - if the client requested protocol version 4.0, which does not exist as of - this writing). If the minor version requested by the client is not - supported by the server (e.g., the client requests version 3.2, but the - server supports only 3.0), the server may either reject the connection or - may respond with a NegotiateProtocolVersion message containing the highest - minor protocol version which it supports. The client may then choose either - to continue with the connection using the specified protocol version or - to abort the connection. - </para> - - <para> - The protocol negotiation was introduced in - <productname>PostgreSQL</productname> version 9.3.21. Earlier versions would - reject the connection if the client requested a minor version that was not - supported by the server. </para> <para> @@ -212,6 +187,85 @@ server versions; the text format is usually the more portable choice. </para> </sect2> + + <sect2 id="protocol-versions"> + <title>Protocol versions</title> + + <para> + The current, latest version of the protocol is version 3.2. However, for + backwards compatibility with old server versions and middleware that don't + support the version negotiation yet, libpq still uses protocol version 3.0 + by default. + </para> + + <para> + A single server can support multiple protocol versions. The initial + startup-request message tells the server which protocol version the client + is attempting to use. If the major version requested by the client is not + supported by the server, the connection will be rejected (for example, + this would occur if the client requested protocol version 4.0, which does + not exist as of this writing). If the minor version requested by the + client is not supported by the server (e.g., the client requests version + 3.2, but the server supports only 3.0), the server may either reject the + connection or may respond with a NegotiateProtocolVersion message + containing the highest minor protocol version which it supports. The + client may then choose either to continue with the connection using the + specified protocol version or to abort the connection. + </para> + + <para> + The protocol negotiation was introduced in + <productname>PostgreSQL</productname> version 9.3.21. Earlier versions + would reject the connection if the client requested a minor version that + was not supported by the server. + </para> + + <table> + <title>Protocol versions</title> + + <tgroup cols="2"> + <thead> + <row> + <entry>Version</entry> + <entry>Supported by</entry> + <entry>Description</entry> + </row> + </thead> + + <tbody> + <row> + <entry>3.2</entry> + <entry>PostgreSQL 18 and later</entry> + <entry>Current latest version. The secret key used in query + cancellation was enlarged from 4 bytes to a variable length field. The + BackendKeyData message was changed to accomodate that, and the CancelRequest + message was redefined to have a variable length payload. + </entry> + </row> + <row> + <entry>3.1</entry> + <entry>-</entry> + <entry>Reserved. Version 3.1 has not been used by any PostgreSQL + version, but it was skipped because old versions of the popular + pgbouncer application had a bug in the protocol negotiation which made + it incorrectly claim that it supported version 3.1. + </entry> + </row> + <row> + <entry>3.0</entry> + <entry>PostgreSQL 7.4 and later</entry> + </row> + <row> + <entry>2.0</entry> + <entry>up to PostgreSQL 13</entry> + <entry>See previous releases of + the <productname>PostgreSQL</productname> documentation for + details</entry> + </row> + </tbody> + </tgroup> + </table> + </sect2> </sect1> <sect1 id="protocol-flow"> |