import { type DuckDBConnection, type DuckDBInstance } from '@duckdb/node-api';
import { type PreparedStatementCacheConfig } from './options.ts';
import type { PgDuckClient } from './pgduck.ts';
export type DuckDBExecutionClient = DuckDBConnection | PgDuckClient;
export type DuckDBClientLike = DuckDBExecutionClient | DuckDBConnectionPool;
export type RowData = Record<string, unknown>;
export interface DuckDBConnectionPool {
    acquire(): Promise<DuckDBExecutionClient>;
    release(connection: DuckDBExecutionClient): void | Promise<void>;
    close?(): Promise<void> | void;
}
export declare function isPool(client: DuckDBClientLike): client is DuckDBConnectionPool;
export interface ExecuteClientOptions {
    /** Return DECIMAL values as exact strings, including nested values. */
    decimalMode?: 'number' | 'string';
    prepareCache?: PreparedStatementCacheConfig;
    /**
     * Read top-level DECIMAL columns as exact strings instead of doubles. The
     * result lists those columns in `exactDecimalColumns`.
     */
    exactDecimals?: boolean;
}
export type ExecuteArraysResult = {
    columns: string[];
    rows: unknown[][];
    /** Indexes of DECIMAL columns read as exact strings (see exactDecimals). */
    exactDecimalColumns?: number[];
};
export interface PrepareParamsOptions {
    rejectStringArrayLiterals?: boolean;
    warnOnStringArrayLiteral?: () => void;
    /** Indexes of params bound to non-array columns. They are never coerced. */
    scalarParamIndexes?: ReadonlySet<number>;
}
export declare function prepareParams(params: unknown[], options?: PrepareParamsOptions): unknown[];
/**
 * Close a connection. A query still running on a node-api connection is
 * interrupted first, because disconnecting under it leaves its promise
 * pending forever. `drainTimeoutMs` bounds the wait for it to settle.
 */
export declare function closeClientConnection(connection: DuckDBExecutionClient, drainTimeoutMs?: number): Promise<void>;
export declare function closeDuckDbInstance(instance: DuckDBInstance): Promise<void>;
export declare function executeOnClient(client: DuckDBClientLike, query: string, params: unknown[], options?: ExecuteClientOptions): Promise<RowData[]>;
export declare function executeArraysOnClient(client: DuckDBClientLike, query: string, params: unknown[], options?: ExecuteClientOptions): Promise<ExecuteArraysResult>;
export interface ExecuteInBatchesOptions {
    rowsPerChunk?: number;
    decimalMode?: 'number' | 'string';
}
export interface ExecuteBatchesRawChunk {
    columns: string[];
    rows: unknown[][];
}
/**
 * Stream results from DuckDB in batches to avoid fully materializing rows in JS.
 */
export declare function executeInBatches(client: DuckDBClientLike, query: string, params: unknown[], options?: ExecuteInBatchesOptions): AsyncGenerator<RowData[], void, void>;
export declare function executeInBatchesRaw(client: DuckDBClientLike, query: string, params: unknown[], options?: ExecuteInBatchesOptions): AsyncGenerator<ExecuteBatchesRawChunk, void, void>;
/**
 * Return columnar results when the underlying node-api exposes an Arrow/columnar API.
 * Falls back to column-major JS arrays when Arrow is unavailable.
 */
export declare function executeArrowOnClient(client: DuckDBClientLike, query: string, params: unknown[], options?: Pick<ExecuteClientOptions, 'decimalMode'>): Promise<unknown>;