/**
 * Explainer (v2.17)
 *
 * Per-DB EXPLAIN abstraction. Returns both parsed ExplainRow[] (best effort)
 * and raw DB output as fallback.
 */
import type { BaseAdapter } from '../adapters/base.js';
import type { ExplainResult } from './query-analyzer-types.js';
export declare class Explainer {
    readonly adapter: BaseAdapter;
    readonly dbType: string;
    constructor(adapter: BaseAdapter, dbType: string);
    explain(sql: string, params?: unknown[]): Promise<ExplainResult>;
    private usesJsonFormat;
    /**
     * 从 rows 中提取 JSON 字符串列。MySQL `EXPLAIN FORMAT=JSON` 返回 1 行 1 列,
     * 列名 `EXPLAIN`;PG `EXPLAIN (FORMAT JSON)` 返回 1 行 1 列,列名 `QUERY PLAN`。
     * 兜底:任何 row 的任何 string value 都试一下 JSON.parse。
     */
    private extractJsonColumn;
    /** 把 JSON plan 解析成扁平的 ExplainRow[](顶层算子),便于 LLM 看到结构。 */
    private parseJsonPlan;
    private walkMysqlPlan;
    private walkPgPlan;
    private buildExplainSql;
    private parsePlan;
}
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