# What changed in apache-arrow

> 10 changes in apache-arrow 21 from its official release notes, upgrade guides and advisories: 4 new APIs and options. Each one cited. Sources checked 2026-10-17. HTML: https://unstale.sh/npm/apache-arrow/

To see which of these apply to a repository, run `npx @unstale/cli init` in it.

## apache-arrow 21

### New APIs and options

- Adds support for the BinaryView type. (21.2.0) — [release notes](https://github.com/apache/arrow-js/releases/tag/v21.2.0)
- Adds custom metadata support for IPC messages and RecordBatch. (21.2.0) — [release notes](https://github.com/apache/arrow-js/releases/tag/v21.2.0)
- Adds LargeList support. (21.2.0) — [release notes](https://github.com/apache/arrow-js/releases/tag/v21.2.0)
- Adds support for the Utf8View type. (21.2.0) — [release notes](https://github.com/apache/arrow-js/releases/tag/v21.2.0)

### Fixes and other changes

- Respects typed-array byteOffset when converting big numbers to strings. (21.2.0) — [release notes](https://github.com/apache/arrow-js/releases/tag/v21.2.0)
- Writes a zero-filled values buffer for fully-null Bool columns in IPC. (21.2.0) — [release notes](https://github.com/apache/arrow-js/releases/tag/v21.2.0)
- Fixes nanosecond precision loss in IntervalMonthDayNano values, including when reading JSON-encoded int64s. (21.2.0) — [release notes](https://github.com/apache/arrow-js/releases/tag/v21.2.0)
- Resolves the TS2352 type error in MapBuilder for TypeScript 5.6 and later. (21.2.0) — [release notes](https://github.com/apache/arrow-js/releases/tag/v21.2.0)
- Preserves numRows for zero-column RecordBatch values in IPC. (21.2.0) — [release notes](https://github.com/apache/arrow-js/releases/tag/v21.2.0)
- Implements Symbol.hasInstance to support cross-library instanceof checks. (21.2.0) — [release notes](https://github.com/apache/arrow-js/releases/tag/v21.2.0)