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) ...

Use the arrow_cast function to cast to a specific arrow type

For example

select arrow_cast(column_x, 'Float64')

Implementations

impl ArrowCastFunc

pub fn new() -> Self

Trait Implementations

impl Debug for ArrowCastFunc

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

Formats the value using the given formatter.

impl Default for ArrowCastFunc

fn default() -> Self

Returns the “default value” for a type.

impl ScalarUDFImpl for ArrowCastFunc

fn as_any(&self) -> &dyn Any

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>

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>

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

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

Invoke the function on args, returning the appropriate result

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

Optionally apply per-UDF simplification / rewrite rules.

fn display_name(&self, args: &[Expr]) -> Result<String, DataFusionError>

Returns the user-defined display name of the UDF given the arguments

fn invoke_no_args( &self, _number_rows: usize, ) -> Result<ColumnarValue, DataFusionError>

Invoke the function without args, instead the number of rows are provided, returning the appropriate result.

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

Returns any aliases (alternate names) for this function.

fn short_circuits(&self) -> bool

Returns true if some of this exprs subexpressions may not be evaluated and thus any side effects (like divide by zero) may not be encountered Setting this to true prevents certain optimizations such as common subexpression elimination

fn evaluate_bounds( &self, _input: &[&Interval], ) -> Result<Interval, DataFusionError>

Computes the output interval for a ScalarUDFImpl, given the input intervals.

fn propagate_constraints( &self, _interval: &Interval, _inputs: &[&Interval], ) -> Result<Option<Vec<Interval>>, DataFusionError>

Updates bounds for child expressions, given a known interval for this function. This is used to propagate constraints down through an expression tree.

fn output_ordering( &self, _inputs: &[ExprProperties], ) -> Result<SortProperties, DataFusionError>

Calculates the SortProperties of this function based on its children’s properties.

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

Coerce arguments of a function call to types that the function can evaluate.

fn equals(&self, other: &dyn ScalarUDFImpl) -> bool

Return true if this scalar UDF is equal to the other.

fn hash_value(&self) -> u64

Returns a hash value for this scalar UDF.