Enum Error 

pub enum Error {
    Connection(String),
    Authentication(String),
    Protocol(String),
    Sql(String),
    JsonDecode(Error),
    Io(Error),
    Config(String),
    Cancelled,
    InvalidSchema(String),
    ConnectionBusy(String),
    InvalidState {
        expected: String,
        actual: String,
    },
    ConnectionClosed,
    Deserialization {
        type_name: String,
        details: String,
    },
    MemoryLimitExceeded {
        limit: usize,
        estimated_memory: usize,
    },
}

Main error type for fraiseql-wire operations

Variants

Connection(String)

Connection error

Authentication(String)

Authentication error

Protocol(String)

Protocol violation

Sql(String)

SQL execution error

JsonDecode(Error)

JSON decoding error

Io(Error)

I/O error

Config(String)

Invalid configuration

Cancelled

Query cancelled by client

InvalidSchema(String)

Invalid result schema (not single data column)

ConnectionBusy(String)

Connection already in use

InvalidState

Invalid connection state

Fields

expected: String

Expected state

actual: String

Actual state

ConnectionClosed

Connection closed

Deserialization

Type deserialization error

Occurs when a row cannot be deserialized into the target type. This is a consumer-side error that includes the type name and serde details.

Fields

type_name: String

Name of the type we were deserializing to

details: String

Details from serde_json about what went wrong

MemoryLimitExceeded

Memory limit exceeded

Terminal error: The consumer cannot keep pace with data arrival.

Occurs when estimated buffered memory exceeds the configured maximum. This indicates the consumer is too slow relative to data arrival rate.

NOT retriable: Retrying the same query with the same consumer will hit the same limit.

Solutions:

1. Increase consumer throughput (faster .next() polling)
2. Reduce items in flight (configure lower chunk_size)
3. Remove memory limit (use unbounded mode)
4. Use different transport (consider tokio-postgres for flexibility)

Fields

limit: usize

Configured memory limit in bytes

estimated_memory: usize

Current estimated memory in bytes (items_buffered * 2048)

Implementations

impl Error

pub fn connection<S: Into<String>>(msg: S) -> Self

Create a connection error with context

pub fn connection_refused(host: &str, port: u16) -> Self

Create a connection refused error (helpful message for debugging)

pub fn protocol<S: Into<String>>(msg: S) -> Self

Create a protocol error with context

pub fn sql<S: Into<String>>(msg: S) -> Self

Create a SQL error with context

pub fn invalid_schema_columns(num_columns: usize) -> Self

Create a schema validation error (query returned wrong columns)

pub fn invalid_schema<S: Into<String>>(msg: S) -> Self

Create an invalid schema error with context

pub fn auth_failed(username: &str, reason: &str) -> Self

Create an authentication error with helpful message

pub fn config_invalid<S: Into<String>>(msg: S) -> Self

Create a config error with helpful message

pub fn is_retriable(&self) -> bool

Check if error is retriable (transient)

Retriable errors typically indicate temporary issues that may succeed on retry:

• I/O errors (network timeouts, etc.)
• Connection closed (can reconnect)

Non-retriable errors indicate permanent problems:

• Invalid schema (won’t change between attempts)
• Invalid configuration (needs user intervention)
• SQL errors (query is invalid)

pub fn category(&self) -> &'static str

Get error category for observability and logging

Used to categorize errors for metrics, tracing, and error handling decisions.

Trait Implementations

impl Debug for Error

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

Formats the value using the given formatter.

impl Display for Error

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

Formats the value using the given formatter.

impl Error for Error

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl From<Error> for Error

fn from(source: Error) -> Self

Converts to this type from the input type.

impl From<Error> for Error

fn from(source: Error) -> Self

Converts to this type from the input type.