Enum BackendMessage 

pub enum BackendMessage {
    AuthenticationOk,
    AuthenticationCleartextPassword,
    AuthenticationMD5Password {
        salt: [u8; 4],
    },
    ParameterStatus {
        name: String,
        value: String,
    },
    BackendKeyData {
        process_id: i32,
        secret_key: i32,
    },
    ReadyForQuery {
        status: TransactionStatus,
    },
    RowDescription {
        fields: Vec<FieldDescription>,
    },
    DataRow {
        values: Vec<Option<Vec<u8>>>,
    },
    CommandComplete {
        tag: String,
    },
    ErrorResponse {
        fields: HashMap<u8, String>,
    },
    NoticeResponse {
        fields: HashMap<u8, String>,
    },
    EmptyQueryResponse,
    SubscriptionData {
        subscription_id: [u8; 16],
        update_type: SubscriptionUpdateType,
        rows: Vec<Vec<Option<Vec<u8>>>>,
    },
    SubscriptionError {
        subscription_id: [u8; 16],
        message: String,
    },
    SubscriptionAck {
        subscription_id: [u8; 16],
        table_count: u16,
    },
    SubscriptionPartialData {
        subscription_id: [u8; 16],
        rows: Vec<PartialRowUpdate>,
    },
}

Backend message types (server -> client)

Variants

AuthenticationOk

Authentication request

AuthenticationCleartextPassword

AuthenticationMD5Password

Fields

salt: [u8; 4]

ParameterStatus

Parameter status

Fields

name: String

value: String

BackendKeyData

Backend key data (for cancellation)

Fields

process_id: i32

secret_key: i32

ReadyForQuery

Ready for query

Fields

status: TransactionStatus

RowDescription

Row description (result set schema)

Fields

fields: Vec<FieldDescription>

DataRow

Data row

Fields

values: Vec<Option<Vec<u8>>>

CommandComplete

Command complete

Fields

tag: String

ErrorResponse

Error response

Fields

fields: HashMap<u8, String>

NoticeResponse

Notice response

Fields

fields: HashMap<u8, String>

EmptyQueryResponse

Empty query response

SubscriptionData

Subscription data (0xF2) - query result update

Fields

subscription_id: [u8; 16]

update_type: SubscriptionUpdateType

rows: Vec<Vec<Option<Vec<u8>>>>

SubscriptionError

Subscription error (0xF3) - subscription error notification

Fields

subscription_id: [u8; 16]

message: String

SubscriptionAck

Subscription acknowledgment (0xF4) - confirms subscription registration Sent immediately after a subscription is registered, before initial data

Fields

subscription_id: [u8; 16]

table_count: u16

Number of table dependencies the subscription monitors

SubscriptionPartialData

Subscription partial data (0xF7) - selective column update

Used for sending only changed columns in row updates, reducing bandwidth for wide tables where only a few columns change frequently.

Wire format:

• 1 byte: Message type (0xF7)
• 4 bytes: Length (big-endian)
• 16 bytes: Subscription ID
• 1 byte: Update type (always SelectiveUpdate = 4)
• 4 bytes: Row count (big-endian)
• For each row:
  • 2 bytes: Total column count (big-endian)
  • N bytes: Column presence bitmap (ceil(total_columns / 8) bytes)
  • For each present column (bit=1):
    • 4 bytes: Value length (-1 for NULL)
    • M bytes: Value data (if length >= 0)

Fields

subscription_id: [u8; 16]

rows: Vec<PartialRowUpdate>

Partial row updates with column bitmaps

Implementations

impl BackendMessage

pub fn encode(&self, buf: &mut BytesMut)

Encode a backend message to 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.

impl PartialEq for BackendMessage

fn eq(&self, other: &BackendMessage) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for BackendMessage