{"Entry":{"collection":"protocol","key":"cancelrequest-f","name":"CancelRequest","aliases":["CancelRequest","Int32(16)"],"metadata":{"aliases":["CancelRequest","Int32(16)"],"category":"Frontend messages","content_hash":"293452d7787c374c237a469e6b5543a8505b093f49eb7f0aeb61f41d3db843f5","imported_at":"2026-09-30T00:40:44.526912+08:00","name":"CancelRequest","name_zh":"","slug":"cancelrequest-f","summary":"CancelRequest is a frontend protocol message. Length of message contents in bytes, including self."}},"Definition":{"Collection":"protocol","Key":"cancelrequest-f","SourceDatabase":"center","Version":"18","SourceTable":"protocol_message","SourceKey":"cancelrequest-f","SourceRevision":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","Facts":{"comparison_data":{"direction":"F","fields":[{"description":"Length of message contents in bytes, including self.","format":"Int32"},{"description":"The cancel request code. The value is chosen to contain 1234 in the most significant 16 bits, and 5678 in the least significant 16 bits. (To avoid confusion, this code must not be the same as any protocol version number.)","format":"Int32(80877102)"},{"description":"The process ID of the target backend.","format":"Int32"},{"description":"The secret key for the target backend. This field extends to the end of the message, indicated by the length field. The maximum key length is 256 bytes.","format":"Byte n"}]},"comparison_hash":"dc899195882d7563007c3329b648b9516242e55a3833c0945e59840954fa37a8","description":["CancelRequest is a frontend protocol message. Length of message contents in bytes, including self."],"direction":"F","facts":[{"label":"Direction","value":"Frontend → backend"},{"label":"First wire field","value":"Int32"},{"label":"Field entries","value":"4"},{"label":"Documented flow contexts","value":"Canceling Requests in Progress; SSL Session Encryption; GSSAPI Session Encryption"}],"fields":[{"description":"Length of message contents in bytes, including self.","format":"Int32"},{"description":"The cancel request code. The value is chosen to contain 1234 in the most significant 16 bits, and 5678 in the least significant 16 bits. (To avoid confusion, this code must not be the same as any protocol version number.)","format":"Int32(80877102)"},{"description":"The process ID of the target backend.","format":"Int32"},{"description":"The secret key for the target backend. This field extends to the end of the message, indicated by the length field. The maximum key length is 256 bytes.","format":"Byte n"}],"manual_html":"\u003cdl\u003e\u003cdd\u003e\n\u003cdiv class=\"variablelist\"\u003e\n\u003cdl class=\"variablelist\"\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(80877102)\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eThe cancel request code. The value is chosen to contain \u003ccode class=\"literal\"\u003e1234\u003c/code\u003e in the most significant 16 bits, and \u003ccode class=\"literal\"\u003e5678\u003c/code\u003e in the least significant 16 bits. (To avoid confusion, this code must not be the same as any protocol version number.)\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\u003eThe process ID of the target backend.\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003eByte\u003cem class=\"replaceable\"\u003e\u003ccode\u003en\u003c/code\u003e\u003c/em\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eThe secret key for the target backend. This field extends to the end of the message, indicated by the length field. 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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":"CancelRequest (F)","sources":[{"label":"PostgreSQL 18 English manual","path":"protocol-message-formats.html","sha256":"53f37652ac2c089e30ada87d8aee7bdd0f26695b03f275302e526a807d2a1f23","url":"/docs/18/protocol-message-formats.html#PROTOCOL-MESSAGE-FORMATS-CANCELREQUEST"}],"tables":[{"columns":[{"key":"c0","label":"Position"},{"key":"c1","label":"Format"},{"key":"c2","label":"Meaning"}],"key":"fields","rows":[{"c0":"1","c1":"Int32","c2":"Length of message contents in bytes, including self."},{"c0":"2","c1":"Int32(80877102)","c2":"The cancel request code. The value is chosen to contain 1234 in the most significant 16 bits, and 5678 in the least significant 16 bits. (To avoid confusion, this code must not be the same as any protocol version number.)"},{"c0":"3","c1":"Int32","c2":"The process ID of the target backend."},{"c0":"4","c1":"Byte n","c2":"The secret key for the target backend. This field extends to the end of the message, indicated by the length field. The maximum key length is 256 bytes."}],"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-CANCELREQUEST"}]},"MeasuredEvidence":{}},"Text":{"Collection":"protocol","Key":"cancelrequest-f","SourceDatabase":"center","Version":"18","Locale":"en","Title":"CancelRequest","Summary":"CancelRequest is a frontend protocol message. Length of message contents in bytes, including self.","BodyHTML":"\u003cdl\u003e\u003cdd\u003e\n\u003cdiv\u003e\n\u003cdl\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(80877102)\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eThe cancel request code. The value is chosen to contain \u003ccode\u003e1234\u003c/code\u003e in the most significant 16 bits, and \u003ccode\u003e5678\u003c/code\u003e in the least significant 16 bits. (To avoid confusion, this code must not be the same as any protocol version number.)\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan\u003eInt32\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eThe process ID of the target backend.\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan\u003eByte\u003cem\u003e\u003ccode\u003en\u003c/code\u003e\u003c/em\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eThe secret key for the target backend. This field extends to the end of the message, indicated by the length field. The maximum key length is 256 bytes.\u003c/p\u003e\n\u003c/dd\u003e\n\u003c/dl\u003e\n\u003c/div\u003e\n\u003cp\u003eBefore protocol version 3.2, the secret key was always 4 bytes long.\u003c/p\u003e\n\u003c/dd\u003e\u003c/dl\u003e","SourceRevision":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","ContentHash":"ac63a58de9eddbf1558d4baf853f72161cfc5ce2e4163cfa93bd45196d8ec7d6","Payload":{"description":["CancelRequest is a frontend protocol message. Length of message contents in bytes, including self."],"manual_html":"\u003cdl\u003e\u003cdd\u003e\n\u003cdiv class=\"variablelist\"\u003e\n\u003cdl class=\"variablelist\"\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(80877102)\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eThe cancel request code. The value is chosen to contain \u003ccode class=\"literal\"\u003e1234\u003c/code\u003e in the most significant 16 bits, and \u003ccode class=\"literal\"\u003e5678\u003c/code\u003e in the least significant 16 bits. (To avoid confusion, this code must not be the same as any protocol version number.)\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\u003eThe process ID of the target backend.\u003c/p\u003e\n\u003c/dd\u003e\n\u003cdt\u003e\u003cspan class=\"term\"\u003eByte\u003cem class=\"replaceable\"\u003e\u003ccode\u003en\u003c/code\u003e\u003c/em\u003e\u003c/span\u003e\u003c/dt\u003e\n\u003cdd\u003e\n\u003cp\u003eThe secret key for the target backend. This field extends to the end of the message, indicated by the length field. The maximum key length is 256 bytes.\u003c/p\u003e\n\u003c/dd\u003e\n\u003c/dl\u003e\n\u003c/div\u003e\n\u003cp\u003eBefore protocol version 3.2, the secret key was always 4 bytes long.\u003c/p\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":"Canceling Requests in Progress","url":"/docs/18/protocol-flow.html#PROTOCOL-FLOW-CANCELING-REQUESTS"},{"label":"SSL Session Encryption","url":"/docs/18/protocol-flow.html#PROTOCOL-FLOW-SSL"},{"label":"GSSAPI Session Encryption","url":"/docs/18/protocol-flow.html#PROTOCOL-FLOW-GSSAPI"}],"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":"Int32","c2":"Length of message contents in bytes, including self."},{"c0":"2","c1":"Int32(80877102)","c2":"The cancel request code. The value is chosen to contain 1234 in the most significant 16 bits, and 5678 in the least significant 16 bits. (To avoid confusion, this code must not be the same as any protocol version number.)"},{"c0":"3","c1":"Int32","c2":"The process ID of the target backend."},{"c0":"4","c1":"Byte n","c2":"The secret key for the target backend. This field extends to the end of the message, indicated by the length field. The maximum key length is 256 bytes."}],"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}