Struct WindowFrame 

pub struct WindowFrame {
    pub units: WindowFrameUnits,
    pub start_bound: WindowFrameBound,
    pub end_bound: WindowFrameBound,
    causal: bool,
}

The frame specification determines which output rows are read by an aggregate window function. The ending frame boundary can be omitted if the BETWEEN and AND keywords that surround the starting frame boundary are also omitted, in which case the ending frame boundary defaults to CURRENT ROW.

Fields

units: WindowFrameUnits

Frame type - either ROWS, RANGE or GROUPS

start_bound: WindowFrameBound

Starting frame boundary

end_bound: WindowFrameBound

Ending frame boundary

causal: bool

Flag indicating whether the frame is causal (i.e. computing the result for the current row doesn’t depend on any subsequent rows).

Example causal window frames:

               +--------------+
     Future    |              |
        |      |              |
        |      |              |
   Current Row |+------------+|  ---
        |      |              |   |
        |      |              |   |
        |      |              |   |  Window Frame 1
      Past     |              |   |
               |              |   |
               |              |  ---
               +--------------+

               +--------------+
     Future    |              |
        |      |              |
        |      |              |
   Current Row |+------------+|
        |      |              |
        |      |              | ---
        |      |              |  |
      Past     |              |  |  Window Frame 2
               |              |  |
               |              | ---
               +--------------+

Example non-causal window frame:

               +--------------+
     Future    |              |
        |      |              |
        |      |              | ---
   Current Row |+------------+|  |
        |      |              |  |  Window Frame 3
        |      |              |  |
        |      |              | ---
      Past     |              |
               |              |
               |              |
               +--------------+

Implementations

impl WindowFrame

pub fn new(order_by: Option<bool>) -> Self

Creates a new, default window frame (with the meaning of default depending on whether the frame contains an ORDER BY clause and this ordering is strict (i.e. no ties).

pub fn reverse(&self) -> Self

Get reversed window frame. For example 3 ROWS PRECEDING AND 2 ROWS FOLLOWING –> 2 ROWS PRECEDING AND 3 ROWS FOLLOWING

pub fn is_causal(&self) -> bool

Get whether window frame is causal

pub fn new_bounds( units: WindowFrameUnits, start_bound: WindowFrameBound, end_bound: WindowFrameBound, ) -> Self

Initializes window frame from units (type), start bound and end bound.

pub fn regularize_order_bys(&self, order_by: &mut Vec<Sort>) -> Result<()>

Regularizes the ORDER BY clause of the window frame.

pub fn can_accept_multi_orderby(&self) -> bool

Returns whether the window frame can accept multiple ORDER BY expressions.

fn free_range(&self) -> bool

Returns whether the window frame is “free range”; i.e. its start/end bounds are UNBOUNDED or CURRENT ROW.

pub fn is_ever_expanding(&self) -> bool

Is the window frame ever-expanding (it always grows in the superset sense). Useful when understanding if set-monotonicity properties of functions can be exploited.

Trait Implementations

impl Clone for WindowFrame

fn clone(&self) -> WindowFrame

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for WindowFrame

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

Formats the value using the given formatter.

impl Display for WindowFrame

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

Formats the value using the given formatter.

impl Hash for WindowFrame

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 WindowFrame

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

fn partial_cmp(&self, other: &WindowFrame) -> 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 TryFrom<WindowFrame> for WindowFrame

type Error = DataFusionError

The type returned in the event of a conversion error.

fn try_from(value: WindowFrame) -> Result<Self>

Performs the conversion.

impl Eq for WindowFrame

impl StructuralPartialEq for WindowFrame