Struct datafusion_expr::expr::WindowFunction

pub struct WindowFunction {
    pub fun: WindowFunctionDefinition,
    pub args: Vec<Expr>,
    pub partition_by: Vec<Expr>,
    pub order_by: Vec<Expr>,
    pub window_frame: WindowFrame,
    pub null_treatment: Option<NullTreatment>,
}

Window function

Holds the actual actual function to call WindowFunction as well as its arguments (args) and the contents of the OVER clause:

1. PARTITION BY
2. ORDER BY
3. Window frame (e.g. ROWS 1 PRECEDING AND 1 FOLLOWING)

Example

// Create FIRST_VALUE(a) OVER (PARTITION BY b ORDER BY c)
let expr = Expr::WindowFunction(
    WindowFunction::new(BuiltInWindowFunction::FirstValue, vec![col("a")])
)
  .partition_by(vec![col("b")])
  .order_by(vec![col("b").sort(true, true)])
  .build()
  .unwrap();

Fields

fun: WindowFunctionDefinition

Name of the function

args: Vec<Expr>

List of expressions to feed to the functions as arguments

partition_by: Vec<Expr>

List of partition by expressions

order_by: Vec<Expr>

List of order by expressions

window_frame: WindowFrame

Window frame

null_treatment: Option<NullTreatment>

Specifies how NULL value is treated: ignore or respect

Implementations

impl WindowFunction

pub fn new(fun: impl Into<WindowFunctionDefinition>, args: Vec<Expr>) -> Self

Create a new Window expression with the specified argument an empty OVER clause

Trait Implementations

impl Clone for WindowFunction

fn clone(&self) -> WindowFunction

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for WindowFunction

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

Formats the value using the given formatter.

impl Hash for WindowFunction

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

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 WindowFunction

fn eq(&self, other: &WindowFunction) -> 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 Eq for WindowFunction

impl StructuralPartialEq for WindowFunction