/**
 * postgres-mcp - Connection Pool Manager
 *
 * Wraps pg connection pooling with health monitoring,
 * statistics tracking, and graceful shutdown support.
 */
import pg from "pg";
import type { PoolClient, QueryResult as PgQueryResult } from "pg";
import type { PoolConfig, PoolStats, HealthStatus } from "../types/index.js";
/**
 * Connection pool configuration with defaults
 */
export interface ConnectionPoolConfig {
    host: string;
    port: number;
    user: string;
    password: string;
    database: string;
    initializationSql?: string[];
    pool?: PoolConfig | undefined;
    ssl?: pg.ConnectionConfig["ssl"] | undefined;
    statementTimeout?: number | undefined;
    applicationName?: string | undefined;
}
/**
 * Connection pool wrapper with statistics and health monitoring
 */
export declare class ConnectionPool {
    private pool;
    private config;
    private initializedConnections;
    private stats;
    private shuttingDown;
    constructor(config: ConnectionPoolConfig);
    /**
     * Initialize the connection pool
     */
    initialize(): Promise<void>;
    /**
     * Get a connection from the pool
     */
    getConnection(): Promise<PoolClient>;
    /**
     * Release a connection back to the pool
     */
    releaseConnection(client: PoolClient): void;
    /**
     * Execute a query using a pooled connection.
     * Routes through getConnection() to ensure initializationSql is applied.
     */
    query<T extends Record<string, unknown>[]>(sql: string, params?: unknown[]): Promise<PgQueryResult<T[number]>>;
    /**
     * Get pool statistics
     */
    getStats(): PoolStats;
    /**
     * Check pool health
     */
    checkHealth(): Promise<HealthStatus>;
    /**
     * Gracefully shutdown the pool
     */
    shutdown(): Promise<void>;
    /**
     * Check if pool is initialized
     */
    isInitialized(): boolean;
    /**
     * Check if pool is shutting down
     */
    isClosing(): boolean;
    /**
     * Apply initialization SQL to a connection if configured and not yet applied.
     * Uses WeakSet tracking so init runs exactly once per physical connection.
     * Releases the connection and throws PoolError on failure.
     */
    private applyInitializationSql;
}
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