CancelRequest

CancelRequest is a frontend protocol message. Length of message contents in bytes, including self.

Reading PG 18·Select a recorded version

Direction: Frontend → backend
First wire field: Int32
Field entries: 4
Documented flow contexts: Canceling Requests in Progress; SSL Session Encryption; GSSAPI Session Encryption
direction: F
manual path: /docs/18/protocol-message-formats.html
signature: CancelRequest (F)

Definition PG 18

Int32: Length of message contents in bytes, including self.
Int32(80877102): 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.)
Int32: The process ID of the target backend.
Byten: 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.

Before protocol version 3.2, the secret key was always 4 bytes long.

Wire fields in documented order

Position	Format	Meaning
1	Int32	Length of message contents in bytes, including self.
2	Int32(80877102)	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.)
3	Int32	The process ID of the target backend.
4	Byte n	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.

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Complete source facts

fields

map[description:Length of message contents in bytes, including self. format:Int32], map[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)], map[description:The process ID of the target backend. format:Int32], map[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]

Source references

Full definition and evidence JSON

Definition sources

center · PostgreSQL 18 · 555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f

Text language: en · 555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f