/**
 * Parallel Parquet generation (`--jobs N`).
 *
 * The text coordinator splits rows; this one splits ROW GROUPS. That is the
 * whole trick: a group's bytes are position-independent (page headers carry
 * sizes, and every offset in the format lives in the footer), so workers can
 * build whole groups on their own and the coordinator only has to lay them end
 * to end, shift the recorded offsets, and write one footer.
 *
 * Splitting on a group boundary rather than an arbitrary row is what keeps the
 * output byte-identical to a single-threaded run: cut mid-group and the file
 * would contain groups a `--jobs 1` run never produces.
 *
 * Measured motivation: a 1M-row config spends ~7s of CPU but only ~1.1 cores,
 * because Parquet was excluded from `--jobs`. The same work spread over the
 * cores the text path already uses brings the wall clock down accordingly.
 */
export interface ParquetParallelParams {
    readonly source: string;
    readonly seed: string;
    readonly count: number;
    /** An override the caller asked for — never a default, or it beats the config's `local=`. */
    readonly locale: string | undefined;
    /** The project config's locale: a fallback for a config that names none. */
    readonly defaultLocale?: string | undefined;
    readonly now: number;
    readonly dataPaths?: readonly string[] | undefined;
    readonly baseDir?: string | undefined;
    readonly jobs: number;
    readonly destFd: number;
    /**
     * Called as the run advances, with the WHOLE file's numbers.
     *
     * Same reason as the text path: above a hundred thousand rows the command
     * line splits the run by itself, so a channel that only worked on one thread
     * was silent exactly when somebody needed it.
     */
    readonly onProgress?: ((progress: {
        phase: 'uniq-scan' | 'uniq-sort' | 'uniq-repair' | 'render';
        done: number;
        total: number;
    }) => void) | undefined;
}
export { parquetJobLimit } from './parallel-plan.js';
/** Generate to `destFd` across worker threads. */
export declare function runParquetParallel(params: ParquetParallelParams): Promise<void>;
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