Enum BackendMessage 

pub enum BackendMessage {
    AuthenticationOk,
    AuthenticationCleartextPassword,
    AuthenticationMD5Password([u8; 4]),
    AuthenticationKerberosV5,
    AuthenticationGSS,
    AuthenticationSCMCredential,
    AuthenticationGSSContinue(Vec<u8>),
    AuthenticationSSPI,
    AuthenticationSASL(Vec<String>),
    AuthenticationSASLContinue(Vec<u8>),
    AuthenticationSASLFinal(Vec<u8>),
    ParameterStatus {
        name: String,
        value: String,
    },
    BackendKeyData {
        process_id: i32,
        secret_key: i32,
    },
    ReadyForQuery(TransactionStatus),
    RowDescription(Vec<FieldDescription>),
    DataRow(Vec<Option<Vec<u8>>>),
    CommandComplete(String),
    ErrorResponse(ErrorFields),
    ParseComplete,
    BindComplete,
    NoData,
    PortalSuspended,
    CopyInResponse {
        format: u8,
        column_formats: Vec<u8>,
    },
    CopyOutResponse {
        format: u8,
        column_formats: Vec<u8>,
    },
    CopyBothResponse {
        format: u8,
        column_formats: Vec<u8>,
    },
    CopyData(Vec<u8>),
    CopyDone,
    NotificationResponse {
        process_id: i32,
        channel: String,
        payload: String,
    },
    EmptyQueryResponse,
    NoticeResponse(ErrorFields),
    ParameterDescription(Vec<u32>),
    CloseComplete,
}

Backend (server → client) message types

Variants

AuthenticationOk

Authentication request Authentication succeeded.

AuthenticationCleartextPassword

Server requests cleartext password.

AuthenticationMD5Password([u8; 4])

Server requests MD5-hashed password; salt provided.

AuthenticationKerberosV5

Server requests Kerberos V5 authentication.

AuthenticationGSS

Server requests GSSAPI authentication.

AuthenticationSCMCredential

Server requests SCM credential auth (Unix-domain peer credential exchange).

PostgreSQL auth code 6. This is typically used with local Unix sockets and requires ancillary credential passing at the socket layer.

AuthenticationGSSContinue(Vec<u8>)

Server sends GSSAPI/SSPI continuation token.

AuthenticationSSPI

Server requests SSPI authentication.

AuthenticationSASL(Vec<String>)

Server initiates SASL handshake with supported mechanisms.

AuthenticationSASLContinue(Vec<u8>)

SASL challenge from server.

AuthenticationSASLFinal(Vec<u8>)

SASL authentication complete; final server data.

ParameterStatus

Parameter status (server config)

Fields

name: String

Parameter name (e.g. server_version, TimeZone).

value: String

Current parameter value.

BackendKeyData

Backend key data (for cancel)

Fields

process_id: i32

Backend process ID (used for cancel requests).

secret_key: i32

Cancel secret key.

ReadyForQuery(TransactionStatus)

Server is ready; transaction state indicated.

RowDescription(Vec<FieldDescription>)

Column metadata for the upcoming data rows.

DataRow(Vec<Option<Vec<u8>>>)

One data row; each element is None for SQL NULL or the raw bytes.

CommandComplete(String)

Command completed with a tag like SELECT 5 or INSERT 0 1.

ErrorResponse(ErrorFields)

Error response with structured fields (severity, code, message, etc.).

ParseComplete

Parse step succeeded.

BindComplete

Bind step succeeded.

NoData

Describe returned no row description (e.g. for DML statements).

PortalSuspended

Execute reached row limit (max_rows) and suspended the portal.

CopyInResponse

Copy in response (server ready to receive COPY data)

Fields

format: u8

Overall format: 0 = text, 1 = binary.

column_formats: Vec<u8>

Per-column format codes.

CopyOutResponse

Copy out response (server will send COPY data)

Fields

format: u8

Overall format: 0 = text, 1 = binary.

column_formats: Vec<u8>

Per-column format codes.

CopyBothResponse

Copy both response (used by streaming replication).

Fields

format: u8

Overall format: 0 = text, 1 = binary.

column_formats: Vec<u8>

Per-column format codes.

CopyData(Vec<u8>)

Raw COPY data chunk from the server.

CopyDone

COPY transfer complete.

NotificationResponse

Notification response (async notification from LISTEN/NOTIFY)

Fields

process_id: i32

Backend process ID that sent the notification.

channel: String

Channel name.

payload: String

Notification payload string.

EmptyQueryResponse

Empty query string was submitted.

NoticeResponse(ErrorFields)

Notice response (warning/info messages, not errors)

ParameterDescription(Vec<u32>)

Parameter description (OIDs of parameters in a prepared statement) Sent by server in response to Describe(Statement)

CloseComplete

Close complete (server confirmation that a prepared statement/portal was released)

Implementations

impl BackendMessage

pub fn decode(buf: &[u8]) -> Result<(Self, usize), String>

Decode a message from wire bytes.

Trait Implementations

impl Clone for BackendMessage

fn clone(&self) -> BackendMessage

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for BackendMessage

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.