/**
 * ClickHouse server error codes this package branches on. `@clickhouse/client`
 * carries them as STRING `code` values on `ClickHouseError`; the literals here
 * are the single source for every class set below.
 */
export declare const CLICKHOUSE_ERROR_CODES: {
    readonly UNKNOWN_TABLE: "60";
    readonly UNKNOWN_DATABASE: "81";
    readonly READONLY: "164";
    readonly UNKNOWN_USER: "192";
    readonly IP_ADDRESS_NOT_ALLOWED: "195";
    readonly QUOTA_EXCEEDED: "201";
    readonly TOO_MANY_SIMULTANEOUS_QUERIES: "202";
    readonly SETTING_CONSTRAINT_VIOLATION: "452";
    readonly ACCESS_DENIED: "497";
    readonly AUTHENTICATION_FAILED: "516";
};
export type ClickHouseErrorCode = (typeof CLICKHOUSE_ERROR_CODES)[keyof typeof CLICKHOUSE_ERROR_CODES];
export type ClickHouseErrorClass = "absent" | "busy" | "denied" | "unreachable" | "indeterminate";
export interface ClickHouseErrorClassification {
    class: ClickHouseErrorClass;
    /** Server code (`"202"`) or Node error code (`"ECONNREFUSED"`) when one was found. */
    code?: string;
    /** `busy` 202 only: the per-user cap (`user`) or the server-wide cap (`server`). */
    scope?: "user" | "server";
    /** Pre-masked via `maskSensitiveOutput` — safe for every sink without re-masking. */
    message: string;
}
/**
 * Classifies any error raised on the ClickHouse path into the verdict the
 * caller needs — `absent` (table/database missing), `busy` (a concurrency or
 * quota cap tripped), `denied` (authentication / authorisation / constraint),
 * `unreachable` (the network or the client's own timeout/abort), or
 * `indeterminate`.
 *
 * Server codes are read from the `code` property (string per
 * `@clickhouse/client`; a numeric code is accepted defensively) or, when a
 * wrapper has flattened the error, from the `Code: NNN.` marker in the
 * message. A wrapper carrying no code of its own but a `cause` is classified
 * by that cause; the wrapper's message is kept. Pre-masked producer:
 * `message` has been through `maskSensitiveOutput` — sinks must not re-mask.
 */
export declare function classifyClickHouseError(err: unknown): ClickHouseErrorClassification;
/** `denied 497` / `unreachable ECONNREFUSED` / `indeterminate` — for error messages and log context. */
export declare function describeClickHouseErrorClass(classification: ClickHouseErrorClassification): string;