Struct WindowUDF 

pub struct WindowUDF { /* private fields */ }

Logical representation of a user-defined window function (UDWF).

A Window Function is called via the SQL OVER clause:

SELECT first_value(col) OVER (PARTITION BY a, b ORDER BY c) FROM foo;

A UDWF is different from a user defined function (UDF) in that it is stateful across batches.

See the documentation on PartitionEvaluator for more details

1. For simple use cases, use create_udwf (examples in simple_udwf.rs).

2. For advanced use cases, use WindowUDFImpl which provides full API access (examples in advanced_udwf.rs).

API Note

This is a separate struct from WindowUDFImpl to maintain backwards compatibility with the older API.

Implementations

impl WindowUDF

pub fn new_from_impl<F>(fun: F) -> WindowUDF

where F: WindowUDFImpl + 'static,

Create a new WindowUDF from a [WindowUDFImpl] trait object

Note this is the same as using the From impl (WindowUDF::from)

pub fn new_from_shared_impl(fun: Arc<dyn WindowUDFImpl>) -> WindowUDF

Create a new WindowUDF from a [WindowUDFImpl] trait object

pub fn inner(&self) -> &Arc<dyn WindowUDFImpl>

Return the underlying WindowUDFImpl trait object for this function

pub fn with_aliases( self, aliases: impl IntoIterator<Item = &'static str>, ) -> WindowUDF

Adds additional names that can be used to invoke this function, in addition to name

If you implement WindowUDFImpl directly you should return aliases directly.

pub fn call(&self, args: Vec<Expr>) -> Expr

creates a Expr that calls the window function with default values for order_by, partition_by, window_frame.

See ExprFunctionExt for details on setting these values.

This utility allows using a user defined window function without requiring access to the registry, such as with the DataFrame API.

pub fn name(&self) -> &str

Returns this function’s name

See WindowUDFImpl::name for more details.

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

Returns the aliases for this function.

pub fn signature(&self) -> &Signature

Returns this function’s signature (what input types are accepted)

See WindowUDFImpl::signature for more details.

pub fn simplify( &self, ) -> Option<Box<dyn Fn(WindowFunction, &dyn SimplifyInfo) -> Result<Expr, DataFusionError>>>

Do the function rewrite

See WindowUDFImpl::simplify for more details.

pub fn expressions( &self, expr_args: ExpressionArgs<'_>, ) -> Vec<Arc<dyn PhysicalExpr>>

Expressions that are passed to the PartitionEvaluator.

See WindowUDFImpl::expressions for more details.

pub fn partition_evaluator_factory( &self, partition_evaluator_args: PartitionEvaluatorArgs<'_>, ) -> Result<Box<dyn PartitionEvaluator>, DataFusionError>

Return a PartitionEvaluator for evaluating this window function

pub fn field( &self, field_args: WindowUDFFieldArgs<'_>, ) -> Result<Arc<Field>, DataFusionError>

Returns the field of the final result of evaluating this window function.

See WindowUDFImpl::field for more details.

pub fn sort_options(&self) -> Option<SortOptions>

Returns custom result ordering introduced by this window function which is used to update ordering equivalences.

See WindowUDFImpl::sort_options for more details.

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

See WindowUDFImpl::coerce_types for more details.

pub fn reverse_expr(&self) -> ReversedUDWF

Returns the reversed user-defined window function when the order of evaluation is reversed.

See WindowUDFImpl::reverse_expr for more details.

pub fn documentation(&self) -> Option<&Documentation>

Returns the documentation for this Window UDF.

Documentation can be accessed programmatically as well as generating publicly facing documentation.

Trait Implementations

impl Clone for WindowUDF

fn clone(&self) -> WindowUDF

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for WindowUDF

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

Formats the value using the given formatter.

impl Display for WindowUDF

Defines how the WindowUDF is shown to users

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

Formats the value using the given formatter.

impl<F> From<F> for WindowUDF

where F: WindowUDFImpl + Send + Sync + 'static,

fn from(fun: F) -> WindowUDF

Converts to this type from the input type.

impl Hash for WindowUDF

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

where H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for WindowUDF

fn eq(&self, other: &WindowUDF) -> 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 WindowUDF

fn partial_cmp(&self, other: &WindowUDF) -> 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 WindowUDF