Trait LogicalType

pub trait LogicalType: Sync + Send {
    // Required methods
    fn native(&self) -> &NativeType;
    fn signature(&self) -> TypeSignature<'_>;

    // Provided method
    fn default_cast_for(&self, origin: &DataType) -> Result<DataType> { ... }
}

Representation of a logical type with its signature and its native backing type.

The logical type is meant to be used during the DataFusion logical planning phase in order to reason about logical types without worrying about their underlying physical implementation.

Extension types

LogicalType is a trait in order to allow the possibility of declaring extension types:

use datafusion_common::types::{LogicalType, NativeType, TypeSignature};

struct JSON {}

impl LogicalType for JSON {
    fn native(&self) -> &NativeType {
        &NativeType::String
    }

   fn signature(&self) -> TypeSignature<'_> {
       TypeSignature::Extension {
           name: "JSON",
           parameters: &[],
       }
   }
}

Required Methods

fn native(&self) -> &NativeType

Get the native backing type of this logical type.

fn signature(&self) -> TypeSignature<'_>

Get the unique type signature for this logical type. Logical types with identical signatures are considered equal.

Provided Methods

fn default_cast_for(&self, origin: &DataType) -> Result<DataType>

Get the default physical type to cast origin to in order to obtain a physical type that is logically compatible with this logical type.

Trait Implementations

impl Debug for dyn LogicalType

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

Formats the value using the given formatter.

impl Hash for dyn LogicalType

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

impl Ord for dyn LogicalType

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

impl PartialEq for dyn LogicalType

fn eq(&self, other: &Self) -> 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 PartialOrd for dyn LogicalType

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Eq for dyn LogicalType

Implementors

impl LogicalType for NativeType