Enum StreamStrategy

pub enum StreamStrategy {
    LeftThisEpoch,
    RightThisEpoch,
}

Decides how to place stream inputs. Given a 3-way join example:

x -> 1* -> 2* ->
x -> 3  -> 4* ->
x -> 5  -> 6  ->

… where n* means lookup this epoch. If user provides the multi-way join order of (a join b) join c, and set the strategy to be StreamStrategy::LeftThisEpoch, then we will place the stream side as:

a -> 1* -> 2* ->
b -> 3  -> 4* ->
c -> 5  -> 6  ->

… where a, the left-most table in multi-way join, passes through most number of lookup-this-epoch.

If strategy is set to StreamStrategy::RightThisEpoch,

c -> 1* -> 2* ->
b -> 3  -> 4* ->
a -> 5  -> 6  ->

… where c, the right-most table in multi-way join, passes through most number of lookup-this-epoch.

More lookup-this-epochs in a lookup row mean more latency when a barrier is flushed. If lookup executor is set to lookup this epoch, it will wait until a barrier from the arrangement side before actually starting lookups and joins.

Variants

LeftThisEpoch

The left-most table will be preferred to be the stream to lookup this epoch.

RightThisEpoch

The right-most table will be preferred to be the stream to lookup this epoch.

Trait Implementations

impl Clone for StreamStrategy

fn clone(&self) -> StreamStrategy

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for StreamStrategy

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

Formats the value using the given formatter.

impl PartialEq for StreamStrategy

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

impl StructuralPartialEq for StreamStrategy