@electric-sql/d2mini/dist/operators/topKWithFractionalIndex.d.ts

D2Mini is a minimal implementation of Differential Dataflow for performing in-memory incremental view maintenance.

import { KeyValue, PipedOperator } from '../types.js';
import { DifferenceStreamReader, DifferenceStreamWriter, UnaryOperator } from '../graph.js';
export interface TopKWithFractionalIndexOptions {
    limit?: number;
    offset?: number;
}
export type TopKChanges<V> = {
    /** Indicates which element moves into the topK (if any) */
    moveIn: IndexedValue<V> | null;
    /** Indicates which element moves out of the topK (if any) */
    moveOut: IndexedValue<V> | null;
};
/**
 * A topK data structure that supports insertions and deletions
 * and returns changes to the topK.
 */
export interface TopK<V> {
    insert(value: V): TopKChanges<V>;
    delete(value: V): TopKChanges<V>;
}
/**
 * Operator for fractional indexed topK operations
 * This operator maintains fractional indices for sorted elements
 * and only updates indices when elements move position
 */
export declare class TopKWithFractionalIndexOperator<K, V1> extends UnaryOperator<[
    K,
    V1
], [
    K,
    IndexedValue<V1>
]> {
    #private;
    constructor(id: number, inputA: DifferenceStreamReader<[K, V1]>, output: DifferenceStreamWriter<[K, [V1, string]]>, comparator: (a: V1, b: V1) => number, options: TopKWithFractionalIndexOptions);
    protected createTopK(offset: number, limit: number, comparator: (a: TaggedValue<V1>, b: TaggedValue<V1>) => number): TopK<TaggedValue<V1>>;
    run(): void;
    processElement(key: K, value: V1, multiplicity: number, result: Array<[[K, [V1, string]], number]>): void;
}
/**
 * Limits the number of results based on a comparator, with optional offset.
 * This works on a keyed stream, where the key is the first element of the tuple.
 * The ordering is within a key group, i.e. elements are sorted within a key group
 * and the limit + offset is applied to that sorted group.
 * To order the entire stream, key by the same value for all elements such as null.
 *
 * Uses fractional indexing to minimize the number of changes when elements move positions.
 * Each element is assigned a fractional index that is lexicographically sortable.
 * When elements move, only the indices of the moved elements are updated, not all elements.
 *
 * @param comparator - A function that compares two elements
 * @param options - An optional object containing limit and offset properties
 * @returns A piped operator that orders the elements and limits the number of results
 */
export declare function topKWithFractionalIndex<K extends T extends KeyValue<infer K, infer _V> ? K : never, V1 extends T extends KeyValue<K, infer V> ? V : never, T>(comparator: (a: V1, b: V1) => number, options?: TopKWithFractionalIndexOptions): PipedOperator<T, KeyValue<K, [V1, string]>>;
export type FractionalIndex = string;
export type IndexedValue<V> = [V, FractionalIndex];
export declare function indexedValue<V>(value: V, index: FractionalIndex): IndexedValue<V>;
export declare function getValue<V>(indexedValue: IndexedValue<V>): V;
export declare function getIndex<V>(indexedValue: IndexedValue<V>): FractionalIndex;
export type Tag = number;
export type TaggedValue<V> = [V, Tag];