Struct datafusion::functions::core::arrow_cast::ArrowCastFunc

pub struct ArrowCastFunc { /* private fields */ }

Implements casting to arbitrary arrow types (rather than SQL types)

Note that the arrow_cast function is somewhat special in that its return depends only on the value of its second argument (not its type)

It is implemented by calling the same underlying arrow cast kernel as normal SQL casts.

For example to cast to int using SQL (which is then mapped to the arrow type Int32)

select cast(column_x as int) ...

You can use the arrow_cast functiont to cast to a specific arrow type

For example

select arrow_cast(column_x, 'Float64')

Implementations

impl ArrowCastFunc

pub fn new() -> ArrowCastFunc

Trait Implementations

impl Debug for ArrowCastFunc

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

Formats the value using the given formatter.

impl Default for ArrowCastFunc

fn default() -> ArrowCastFunc

Returns the “default value” for a type.

impl ScalarUDFImpl for ArrowCastFunc

fn as_any(&self) -> &(dyn Any + 'static)

Returns this object as an Any trait object

fn name(&self) -> &str

Returns this function’s name

fn signature(&self) -> &Signature

Returns the function’s Signature for information about what input types are accepted and the function’s Volatility.

fn return_type( &self, _arg_types: &[DataType] ) -> Result<DataType, DataFusionError>

What DataType will be returned by this function, given the types of the arguments.

fn return_type_from_exprs( &self, args: &[Expr], _schema: &dyn ExprSchema, _arg_types: &[DataType] ) -> Result<DataType, DataFusionError>

What DataType will be returned by this function, given the arguments?

fn invoke( &self, _args: &[ColumnarValue] ) -> Result<ColumnarValue, DataFusionError>

Invoke the function on args, returning the appropriate result

fn simplify( &self, args: Vec<Expr>, info: &dyn SimplifyInfo ) -> Result<ExprSimplifyResult, DataFusionError>

Optionally apply per-UDF simplification / rewrite rules.

fn aliases(&self) -> &[String]

Returns any aliases (alternate names) for this function.

fn monotonicity(&self) -> Result<Option<Vec<Option<bool>>>, DataFusionError>

This function specifies monotonicity behaviors for User defined scalar functions.