@itwin/core-backend/lib/esm/PartialChangeUnifier.d.ts

iTwin.js backend components

import { ChangeInstance, ChangeSource } from "./ChangesetReaderTypes";
/**
 * Cache used by [[PartialChangeUnifier]] to accumulate and merge
 * partial EC change instances.
 * @beta
 */
export interface ChangeCache extends Disposable {
    /** Retrieve a cached instance by key, or `undefined` if absent. */
    get(key: string): ChangeInstance | undefined;
    /** Insert or replace a cached instance. */
    set(key: string, value: ChangeInstance): void;
    /** Iterate over all cached instances. */
    all(): IterableIterator<ChangeInstance>;
    /** Number of instances currently in the cache. */
    count(): number;
}
/** @beta */
export declare namespace ChangeUnifierCache {
    /**
     * Creates an in-memory cache backed by a `Map`.
     * Fast, but may exhaust memory for very large changesets.
     * @returns An [[ChangeCache]] backed by an in-memory `Map`.
     * @beta
     */
    function createInMemoryCache(): ChangeCache;
    /**
     * Creates a SQLite-backed cache stored in a temporary SQlite database.
     * Slower than in-memory but useful in handling large changesets.
     * Temporary SQlite database is first created in memory and
     * parts of a temporary database might be flushed to disk if the database becomes large or
     * if SQLite comes under memory pressure.
     * @param bufferedReadInstanceSizeInBytes Read-batch size in bytes (default 10 MB).
     * @returns An [[ChangeCache]] backed by a SQLite temp table.
     * @beta
     */
    function createSqliteBackedCache(bufferedReadInstanceSizeInBytes?: number): ChangeCache;
}
/**
 * Combines partial EC change instances (one per SQLite table row) into complete
 * instances that span all tables mapping to a single EC entity.
 *
 * The merge key is derived from the `instanceKey` and `stage` stored in `$meta.instanceKey` and `$meta.stage`.
 *
 * **Usage:**
 * ```ts
 * using reader = ChangesetReader.openFile({ fileName, db });
 * using unifier = new PartialChangeUnifier();
 * while (reader.step()) {
 *   unifier.appendFrom(reader);
 * }
 * for (const instance of unifier.instances) { ... }
 * ```
 * @beta
 */
export declare class PartialChangeUnifier implements Disposable {
    private readonly _cache;
    constructor(_cache?: ChangeCache);
    /** Releases the underlying cache. */
    [Symbol.dispose](): void;
    /** Number of complete (merged) instances currently accumulated. */
    get instanceCount(): number;
    /**
     * Append partial changes from the current reader row and merge them into the cache.
     *
     * @param source Any [ChangeSource]($backend) positioned on a valid row.
     * @beta
     */
    appendFrom(source: ChangeSource): void;
    /**
     * Iterator over all fully-merged EC change instances.
     * @beta
     */
    get instances(): IterableIterator<ChangeInstance>;
    private buildKey;
    private combine;
}
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