@uwdata/mosaic-sql/dist/src/ast/sample.js

SQL query construction and analysis.

import { SAMPLE_CLAUSE } from '../constants.js';
import { SQLNode } from './node.js';
export class SampleClauseNode extends SQLNode {
    /** The sample size as either a row count or percentage. */
    size;
    /** Flag if the sampling unit is rows (`false`) or percentage (`true`). */
    perc;
    /** The sampling method. */
    method;
    /** The random seed. */
    seed;
    /**
     * Instantiate a sample clause node.
     * @param size The sample size as either a row count or percentage.
     * @param perc Flag indicating if the sampling unit is
     *   rows (`false`) or a percentage (`true`).
     * @param method The sampling method. If unspecified,
     *   a default method is applied based on the sampling unit.
     * @param seed The random seed.
     */
    constructor(size, perc = false, method, seed) {
        super(SAMPLE_CLAUSE);
        this.size = size;
        this.perc = perc;
        this.method = method;
        this.seed = seed;
    }
    /**
     * Generate a SQL query string for this node.
     */
    toString() {
        const { size, perc, method, seed } = this;
        const m = method ? `${method} ` : '';
        const s = seed != null ? ` REPEATABLE (${seed})` : '';
        return `${m}(${size}${perc ? '%' : ' ROWS'})${s}`;
    }
}
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