import { createClient } from "@clickhouse/client";
import { NodeClickHouseClientConfigOptions } from "@clickhouse/client/dist/config";
export type ClickhouseClientType = ReturnType<typeof createClient>;
export type PreferredClickhouseService = "ReadWrite" | "ReadOnly";
/**
 * ClickHouseClientManager provides a singleton pattern for managing ClickHouse clients.
 * It creates and reuses clients based on their configuration to avoid creating
 * a new connection for each query.
 */
export declare class ClickHouseClientManager {
    private static instance;
    private clientMap;
    /**
     * Private constructor to enforce singleton pattern
     */
    private constructor();
    /**
     * Get the singleton instance of the ClickHouseClientManager
     */
    static getInstance(): ClickHouseClientManager;
    /**
     * Generate a consistent hash key for client configurations
     * @param opts Client parameters
     * @returns String hash key
     */
    private generateClientSettings;
    private generateClientSettingsKey;
    private getClickhouseUrl;
    /**
     * Get or create a client based on the provided parameters
     * @param opts Client configuration parameters
     * @returns ClickHouse client instance
     */
    getClient(opts: NodeClickHouseClientConfigOptions, preferredClickhouseService?: PreferredClickhouseService): ClickhouseClientType;
    /**
     * Close all client connections - useful for application shutdown
     */
    closeAllConnections(): Promise<void[]>;
}
export declare const clickhouseClient: (opts?: NodeClickHouseClientConfigOptions, preferredClickhouseService?: PreferredClickhouseService) => import("@clickhouse/client").ClickHouseClient;
/**
 * Accepts a JavaScript date and returns the DateTime in format YYYY-MM-DD HH:MM:SS
 */
export declare const convertDateToClickhouseDateTime: (date: Date) => string;
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