Enum datafusion_physical_plan::InputOrderMode

pub enum InputOrderMode {
    Linear,
    PartiallySorted(Vec<usize>),
    Sorted,
}

Specifies how the input to an aggregation or window operator is ordered relative to their GROUP BY or PARTITION BY expressions.

For example, if the existing ordering is [a ASC, b ASC, c ASC]

Window Functions

• A PARTITION BY b clause can use Linear mode.
• A PARTITION BY a, c or a PARTITION BY c, a can use PartiallySorted([0]) or PartiallySorted([1]) modes, respectively. (The vector stores the index of a in the respective PARTITION BY expression.)
• A PARTITION BY a, b or a PARTITION BY b, a can use Sorted mode.

Aggregations

• A GROUP BY b clause can use Linear mode, as the only one permutation [b] cannot satisfy the existing ordering.
• A GROUP BY a, c or a GROUP BY c, a can use PartiallySorted([0]) or PartiallySorted([1]) modes, respectively, as the permutation [a] satisfies the existing ordering. (The vector stores the index of a in the respective PARTITION BY expression.)
• A GROUP BY a, b or a GROUP BY b, a can use Sorted mode, as the full permutation [a, b] satisfies the existing ordering.

Note these are the same examples as above, but with GROUP BY instead of PARTITION BY to make the examples easier to read.

Variants

Linear

There is no partial permutation of the expressions satisfying the existing ordering.

PartiallySorted(Vec<usize>)

There is a partial permutation of the expressions satisfying the existing ordering. Indices describing the longest partial permutation are stored in the vector.

Sorted

There is a (full) permutation of the expressions satisfying the existing ordering.

Trait Implementations

impl Clone for InputOrderMode

fn clone(&self) -> InputOrderMode

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for InputOrderMode

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

Formats the value using the given formatter.

impl PartialEq for InputOrderMode

fn eq(&self, other: &InputOrderMode) -> 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 StructuralPartialEq for InputOrderMode