{"Entry":{"collection":"protocol","key":"negotiateprotocolversion-b","name":"NegotiateProtocolVersion","aliases":["NegotiateProtocolVersion","Byte1('v')"],"metadata":{"aliases":["NegotiateProtocolVersion","Byte1('v')"],"category":"Backend messages","content_hash":"a8f053909db5a27dae5755005b0f0ebd9fdf2bf3f1aa4efacb980f706677da4d","imported_at":"2026-09-30T00:40:44.47683+08:00","name":"NegotiateProtocolVersion","name_zh":"","slug":"negotiateprotocolversion-b","summary":"NegotiateProtocolVersion is a backend protocol message. Identifies the message as a protocol version negotiation message."}},"Definition":{"Collection":"protocol","Key":"negotiateprotocolversion-b","SourceDatabase":"center","Version":"18","SourceTable":"protocol_message","SourceKey":"negotiateprotocolversion-b","SourceRevision":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","Facts":{"comparison_data":{"direction":"B","fields":[{"description":"Identifies the message as a protocol version negotiation message.","format":"Byte1('v')"},{"description":"Length of message contents in bytes, including self.","format":"Int32"},{"description":"Newest minor protocol version supported by the server for the major protocol version requested by the client.","format":"Int32"},{"description":"Number of protocol options not recognized by the server.","format":"Int32"},{"description":"The option name.","format":"String"}]},"comparison_hash":"e1b8b535cfb24c3820d56a4669f869a4b863ed8bb22fa5147c2e8e69a7deb2ba","description":["NegotiateProtocolVersion is a backend protocol message. Identifies the message as a protocol version negotiation message."],"direction":"B","facts":[{"label":"Direction","value":"Backend → frontend"},{"label":"First wire field","value":"Byte1('v')"},{"label":"Field entries","value":"5"},{"label":"Documented flow contexts","value":"Start-up"}],"fields":[{"description":"Identifies the message as a protocol version negotiation message.","format":"Byte1('v')"},{"description":"Length of message contents in bytes, including self.","format":"Int32"},{"description":"Newest minor protocol version supported by the server for the major protocol version requested by the client.","format":"Int32"},{"description":"Number of protocol options not recognized by the server.","format":"Int32"},{"description":"The option name.","format":"String"}],"manual_html":"\u003cdl\u003e\u003cdd\u003e\n\u003cdiv class=\"variablelist\"\u003e\n\u003cdl class=\"variablelist\"\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003eByte1('v')\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eIdentifies the message as a protocol version negotiation message.\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003eInt32\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eLength of message contents in bytes, including self.\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003eInt32\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eNewest minor protocol version supported by the server for the major protocol version requested by the client.\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003eInt32\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eNumber of protocol options not recognized by the server.\u003c/p\u003e\n\u003c/dd\u003e\n\u003c/dl\u003e\n\u003c/div\u003e\n\u003cp\u003eThen, for protocol option not recognized by the server, there is the following:\u003c/p\u003e\n\u003cdiv class=\"variablelist\"\u003e\n\u003cdl class=\"variablelist\"\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003eString\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eThe option name.\u003c/p\u003e\n\u003c/dd\u003e\n\u003c/dl\u003e\n\u003c/div\u003e\n\u003c/dd\u003e\u003c/dl\u003e","manual_path":"/docs/18/protocol-message-formats.html","related":[{"label":"Protocol flow and exchange examples","url":"/docs/18/protocol-flow.html"},{"label":"Protocol overview","url":"/docs/18/protocol-overview.html"},{"label":"Start-up","url":"/docs/18/protocol-flow.html#PROTOCOL-FLOW-START-UP"}],"release":{"channel":"stable","label":"18.6","major":"18","ref":"https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2","revision":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"},"sections":[{"paragraphs":["The complete definition below retains repetition, counts and conditional fields. A numbered table row is a documented field definition, not a fixed byte offset. Integer encodings and flow rules follow the same-version protocol chapter."],"title":"Framing and repetition"}],"signature":"NegotiateProtocolVersion (B)","sources":[{"label":"PostgreSQL 18 English manual","path":"protocol-message-formats.html","sha256":"53f37652ac2c089e30ada87d8aee7bdd0f26695b03f275302e526a807d2a1f23","url":"/docs/18/protocol-message-formats.html#PROTOCOL-MESSAGE-FORMATS-NEGOTIATEPROTOCOLVERSION"}],"tables":[{"columns":[{"key":"c0","label":"Position"},{"key":"c1","label":"Format"},{"key":"c2","label":"Meaning"}],"key":"fields","rows":[{"c0":"1","c1":"Byte1('v')","c2":"Identifies the message as a protocol version negotiation message."},{"c0":"2","c1":"Int32","c2":"Length of message contents in bytes, including self."},{"c0":"3","c1":"Int32","c2":"Newest minor protocol version supported by the server for the major protocol version requested by the client."},{"c0":"4","c1":"Int32","c2":"Number of protocol options not recognized by the server."},{"c0":"5","c1":"String","c2":"The option name."}],"title":"Wire fields in documented order"}]},"ManualEvidence":{"manual_path":"/docs/18/protocol-message-formats.html","release":{"channel":"stable","label":"18.6","major":"18","ref":"https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2","revision":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"},"sources":[{"label":"PostgreSQL 18 English manual","path":"protocol-message-formats.html","sha256":"53f37652ac2c089e30ada87d8aee7bdd0f26695b03f275302e526a807d2a1f23","url":"/docs/18/protocol-message-formats.html#PROTOCOL-MESSAGE-FORMATS-NEGOTIATEPROTOCOLVERSION"}]},"MeasuredEvidence":{}},"Text":{"Collection":"protocol","Key":"negotiateprotocolversion-b","SourceDatabase":"center","Version":"18","Locale":"en","Title":"NegotiateProtocolVersion","Summary":"NegotiateProtocolVersion is a backend protocol message. Identifies the message as a protocol version negotiation message.","BodyHTML":"\u003cdl\u003e\u003cdd\u003e\n\u003cdiv\u003e\n\u003cdl\u003e\n\u003cdt\u003e\u003cspan\u003eByte1(\u0026#39;v\u0026#39;)\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eIdentifies the message as a protocol version negotiation message.\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan\u003eInt32\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eLength of message contents in bytes, including self.\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan\u003eInt32\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eNewest minor protocol version supported by the server for the major protocol version requested by the client.\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan\u003eInt32\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eNumber of protocol options not recognized by the server.\u003c/p\u003e\n\u003c/dd\u003e\n\u003c/dl\u003e\n\u003c/div\u003e\n\u003cp\u003eThen, for protocol option not recognized by the server, there is the following:\u003c/p\u003e\n\u003cdiv\u003e\n\u003cdl\u003e\n\u003cdt\u003e\u003cspan\u003eString\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eThe option name.\u003c/p\u003e\n\u003c/dd\u003e\n\u003c/dl\u003e\n\u003c/div\u003e\n\u003c/dd\u003e\u003c/dl\u003e","SourceRevision":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","ContentHash":"59707438c9b4b93510351e7e339c82d3b5fee1fbc49cacd1619ab7a980108a49","Payload":{"description":["NegotiateProtocolVersion is a backend protocol message. Identifies the message as a protocol version negotiation message."],"manual_html":"\u003cdl\u003e\u003cdd\u003e\n\u003cdiv class=\"variablelist\"\u003e\n\u003cdl class=\"variablelist\"\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003eByte1('v')\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eIdentifies the message as a protocol version negotiation message.\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003eInt32\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eLength of message contents in bytes, including self.\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003eInt32\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eNewest minor protocol version supported by the server for the major protocol version requested by the client.\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003eInt32\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eNumber of protocol options not recognized by the server.\u003c/p\u003e\n\u003c/dd\u003e\n\u003c/dl\u003e\n\u003c/div\u003e\n\u003cp\u003eThen, for protocol option not recognized by the server, there is the following:\u003c/p\u003e\n\u003cdiv class=\"variablelist\"\u003e\n\u003cdl class=\"variablelist\"\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003eString\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eThe option name.\u003c/p\u003e\n\u003c/dd\u003e\n\u003c/dl\u003e\n\u003c/div\u003e\n\u003c/dd\u003e\u003c/dl\u003e","related":[{"label":"Protocol flow and exchange examples","url":"/docs/18/protocol-flow.html"},{"label":"Protocol overview","url":"/docs/18/protocol-overview.html"},{"label":"Start-up","url":"/docs/18/protocol-flow.html#PROTOCOL-FLOW-START-UP"}],"sections":[{"paragraphs":["The complete definition below retains repetition, counts and conditional fields. A numbered table row is a documented field definition, not a fixed byte offset. Integer encodings and flow rules follow the same-version protocol chapter."],"title":"Framing and repetition"}],"tables":[{"columns":[{"key":"c0","label":"Position"},{"key":"c1","label":"Format"},{"key":"c2","label":"Meaning"}],"key":"fields","rows":[{"c0":"1","c1":"Byte1('v')","c2":"Identifies the message as a protocol version negotiation message."},{"c0":"2","c1":"Int32","c2":"Length of message contents in bytes, including self."},{"c0":"3","c1":"Int32","c2":"Newest minor protocol version supported by the server for the major protocol version requested by the client."},{"c0":"4","c1":"Int32","c2":"Number of protocol options not recognized by the server."},{"c0":"5","c1":"String","c2":"The option name."}],"title":"Wire fields in documented order"}]}},"RequestedLocale":"zh-Hans","Fallback":true,"Versions":["10","11","12","13","14","15","16","17","18","19","20"],"Locales":["en"],"Signatures":null,"Spellings":null,"SQLState":null,"Evidence":null}