Trait differential_dataflow::operators::join::JoinUnsigned [−] [src]

pub trait JoinUnsigned<G: Scope, U: Unsigned + Data + Default, V: Data> where G::Timestamp: LeastUpperBound {
    fn join_map_u<V2: Data, D: Data, R: Fn(&U, &V, &V2) -> D + 'static>(&self, other: &Collection<G, (U, V2)>, logic: R) -> Collection<G, D>;
    fn semijoin_u(&self, other: &Collection<G, U>) -> Collection<G, (U, V)>;

    fn join_u<V2: Data>(&self, other: &Collection<G, (U, V2)>) -> Collection<G, (U, V, V2)> { ... }
}

Matches pairs (key, val1) and (key, val2) for dense unsigned integer keys.

These methods are optimizations of the general Join trait to use Vec indices rather than a more generic hash map. This can substantially reduce the amount of computation and memory required, but it will allocate as much memory as the largest identifier and so may have poor performance if the absolute range of keys is large.

These method may be deprecated in preferences of an approach which allows implementors of Data to define their own approach to indexing data. In this case, a newtype wrapping dense unsigned integers would indicate the indexing strategy, and the methods would simply be as above.

Required Methods

fn join_map_u<V2: Data, D: Data, R: Fn(&U, &V, &V2) -> D + 'static>(&self, other: &Collection<G, (U, V2)>, logic: R) -> Collection<G, D>

Joins two collections with dense unsigned integer keys and then applies a map function.

Examples

extern crate timely;
use timely::dataflow::operators::{ToStream, Capture};
use timely::dataflow::operators::capture::Extract;
use differential_dataflow::operators::Join;

let data = timely::example(|scope| {
    let col1 = vec![((0,0),1),((1,2),1)].into_iter().to_stream(scope);
    let col2 = vec![((0,'a'),1),((1,'B'),1)].into_iter().to_stream(scope);

    // should produce records `(0 + 0,'a')` and `(1 + 2,'B')`.
    col1.join_map_u(&col2, |k,v1,v2| (*k + *v1, *v2)).capture();
});

let extracted = data.extract();
assert_eq!(extracted.len(), 1);
assert_eq!(extracted[0].1, vec![((0,'a'),1), ((3,'B'),1)]);

fn semijoin_u(&self, other: &Collection<G, U>) -> Collection<G, (U, V)>

Semijoins a collection with dense unsigned integer keys against a set of such keys.

Examples

extern crate timely;
use timely::dataflow::operators::{ToStream, Capture};
use timely::dataflow::operators::capture::Extract;
use differential_dataflow::operators::Join;

let data = timely::example(|scope| {
    let col1 = vec![((0,0),1),((1,2),1)].into_iter().to_stream(scope);
    let col2 = vec![(0,1)].into_iter().to_stream(scope);

    // should retain record `(0,0)` and discard `(1,2)`.
    col1.semijoin(&col2).capture();
});

let extracted = data.extract();
assert_eq!(extracted.len(), 1);
assert_eq!(extracted[0].1, vec![((0,0),1)]);

Provided Methods

fn join_u<V2: Data>(&self, other: &Collection<G, (U, V2)>) -> Collection<G, (U, V, V2)>

Joins two collections with dense unsigned integer keys.

Examples

extern crate timely;
use timely::dataflow::operators::{ToStream, Capture};
use timely::dataflow::operators::capture::Extract;
use differential_dataflow::operators::Join;

let data = timely::example(|scope| {
    let col1 = vec![((0,0),1),((1,2),1)].into_iter().to_stream(scope);
    let col2 = vec![((0,'a'),1),((1,'B'),1)].into_iter().to_stream(scope);

    // should produce triples `(0,0,'a')` and `(1,2,'B')`.
    col1.join_u(&col2).capture();
});

let extracted = data.extract();
assert_eq!(extracted.len(), 1);
assert_eq!(extracted[0].1, vec![((0,0,'a'),1), ((1,2,'B'),1)]);

Implementors