diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/protocol.sgml | 117 |
1 files changed, 106 insertions, 11 deletions
diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml index 4d3b6446c41..999fa060188 100644 --- a/doc/src/sgml/protocol.sgml +++ b/doc/src/sgml/protocol.sgml @@ -22,10 +22,18 @@ <productname>PostgreSQL</productname> 7.4 and later. For descriptions of the earlier protocol versions, see previous releases of the <productname>PostgreSQL</productname> documentation. 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, and then the server follows that protocol - if it is able. + 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 3.1, 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> @@ -406,6 +414,21 @@ </listitem> </varlistentry> + <varlistentry> + <term>NegotiateProtocolVersion</term> + <listitem> + <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 + options (i.e. beginning with <literal>_pq_.</literal>) in the + startup packet. This message will be followed by an ErrorResponse or + a message indicating the success or failure of authentication. + </para> + </listitem> + </varlistentry> + </variablelist> </para> @@ -420,8 +443,10 @@ for further messages from the server. In this phase a backend process is being started, and the frontend is just an interested bystander. It is still possible for the startup attempt - to fail (ErrorResponse), but in the normal case the backend will send - some ParameterStatus messages, BackendKeyData, and finally ReadyForQuery. + to fail (ErrorResponse) or the server to decline support for the requested + minor protocol version (NegotiateProtocolVersion), but in the normal case + the backend will send some ParameterStatus messages, BackendKeyData, and + finally ReadyForQuery. </para> <para> @@ -4715,6 +4740,74 @@ GSSResponse (F) </listitem> </varlistentry> +<varlistentry> +<term> +NegotiateProtocolVersion (B) +</term> +<listitem> +<para> + +<variablelist> +<varlistentry> +<term> + Byte1('v') +</term> +<listitem> +<para> + Identifies the message as a protocol version negotiation + message. +</para> +</listitem> +</varlistentry> +<varlistentry> +<term> + Int32 +</term> +<listitem> +<para> + Length of message contents in bytes, including self. +</para> +</listitem> +</varlistentry> +<varlistentry> +<term> + Int32 +</term> +<listitem> +<para> + Newest minor protocol version supported by the server + for the major protocol version requested by the client. +</para> +</listitem> +</varlistentry> +<varlistentry> +<term> + Int32 +</term> +<listitem> +<para> + Number of protocol options not recognized by the server. +</para> +</listitem> +</varlistentry> +</variablelist> + Then, for protocol option not recognized by the server, there + is the following: +<variablelist> +<varlistentry> +<term> + String +</term> +<listitem> +<para> + The option name. +</para> +</listitem> +</varlistentry> +</variablelist> +</para> +</listitem> +</varlistentry> <varlistentry> <term> @@ -5670,11 +5763,13 @@ StartupMessage (F) </varlistentry> </variablelist> - In addition to the above, any run-time parameter that can be - set at backend start time might be listed. Such settings - will be applied during backend start (after parsing the - command-line arguments if any). The values will act as - session defaults. + In addition to the above, others parameter may be listed. + Parameter names beginning with <literal>_pq_.</literal> are + reserved for use as protocol extensions, while others are + treated as run-time parameters to be set at backend start + time. Such settings will be applied during backend start + (after parsing the command-line arguments if any) and will + act as session defaults. </para> </listitem> </varlistentry> |