import { Schema, TypeMap } from 'apache-arrow';
import { TTableSchema } from '../../thrift/TCLIService_types';
/**
 * Sum the row counts of every RecordBatch message in an Arrow IPC
 * stream, WITHOUT materializing the Arrow vector tree.
 *
 * Why this exists: `ArrowResultConverter` consumes `ArrowBatch` objects
 * that carry an explicit `rowCount`, but the kernel's IPC payload only
 * carries per-RecordBatch `length` (no separate total). `KernelResultsProvider`
 * needs that count to build the `ArrowBatch` it hands to the converter —
 * which then re-decodes the same bytes for the actual values.
 *
 * The previous implementation used `RecordBatchReader` and iterated the
 * batches, which calls `_loadVectors` and materializes the full vector
 * tree for every batch just to read `numRows` and discard everything
 * else — ~2x Arrow decode CPU + transient allocation on the fetch hot
 * path. `MessageReader` instead reads only each message's FlatBuffer
 * metadata header (where `RecordBatch.length` lives) and skips the body
 * bytes, so no vectors are decoded here. The converter's later re-decode
 * is the only real materialization.
 *
 * `ipcBytes` must already be Duration-patched (row count is unaffected
 * by the Duration→Int64 rewrite, and the framing is unchanged). Returns
 * 0 for an empty / schema-only stream.
 */
export declare function countRowsInIpc(ipcBytes: Buffer): number;
/**
 * Decode an Arrow IPC schema payload (no record batches) into the
 * apache-arrow Schema object.
 */
export declare function decodeIpcSchema(ipcBytes: Buffer): Schema<TypeMap>;
/**
 * Pre-process raw IPC bytes from the kernel so they're consumable by
 * `apache-arrow@13`. The current transformation is `Duration → Int64`
 * with the original duration unit preserved in field metadata (see
 * `KernelArrowIpcDurationFix.ts`). Returned bytes are byte-identical to
 * the input when no transformation is needed.
 *
 * Exposed so callers can pre-patch the buffer **once** and pass the
 * result through both `decodeIpcBatch` (for row-count extraction in
 * `KernelResultsProvider`) and `ArrowResultConverter.fetchNext` (which
 * re-decodes the same bytes via `RecordBatchReader.from`). Without
 * this, the converter would re-throw on `Duration` because it never
 * sees the patched bytes.
 */
export declare function patchIpcBytes(ipcBytes: Buffer): Buffer;
/**
 * Synthesize a Thrift `TTableSchema` from an Arrow schema decoded out
 * of the kernel's IPC stream. Used by `KernelOperationBackend.getResultMetadata`
 * to drive `ArrowResultConverter.convertThriftTypes` (Phase 2) without
 * changing that code.
 */
export declare function arrowSchemaToThriftSchema(arrowSchema: Schema<TypeMap>): TTableSchema;