import type { Sql } from "postgres";
/**
 * Sets up required schema (tables and indexes) for PostgreSQL lock backend.
 *
 * Creates (if not exist):
 * - Lock table with primary key on 'key' and indexes on 'lock_id' and 'expires_at_ms'
 * - Fence counter table with primary key on 'fence_key'
 *
 * This is an idempotent operation and safe to call multiple times.
 * Call this once during application initialization, before creating lock backends.
 *
 * @param sql - postgres.js SQL instance
 * @param options - Optional configuration for table names
 * @returns Promise that resolves when schema is created
 *
 * @example
 * ```typescript
 * import postgres from 'postgres';
 * import { setupSchema, createLock } from 'syncguard/postgres';
 *
 * const sql = postgres('postgresql://localhost:5432/myapp');
 *
 * // Setup phase (once, during initialization)
 * await setupSchema(sql);
 *
 * // Usage phase (synchronous)
 * const lock = createLock(sql);
 * ```
 */
export declare function setupSchema(sql: Sql, options?: {
    tableName?: string;
    fenceTableName?: string;
}): Promise<void>;