Starting with version 1.0.0, Apache Arrow uses two versions to describe each release of the project: the Format Version and the Library Version. Each Library Version has a corresponding Format Version, and multiple versions of the library may have the same format version. For example, library versions 2.0.0 and 3.0.0 may both track format version 1.0.0. See :doc:`../status` for details about supported features in each library.
For library versions prior to 1.0.0, major releases may contain API changes. From 1.0.0 onward, we follow Semantic Versioning with regards to communicating API changes. We expect most releases to be major library releases.
A newer versioned client library will be able to read any data and metadata produced by an older client library.
So long as the major format version is not changed, a newer library is backward compatible with an older library.
An older client library must be able to either read data generated from a new client library or detect that it cannot properly read the data.
An increase in the minor version of the format version, such as 1.0.0 to 1.1.0, indicates that 1.1.0 contains new features not available in 1.0.0. So long as these features are not used (such as a new data type), forward compatibility is preserved.
A change in the format major version (e.g. from 1.0.0 to 2.0.0) indicates a disruption to these compatibility guarantees in some way. We do not expect this to be a frequent occurrence. This would be an exceptional event and, should this come to pass, we would exercise caution in ensuring that production applications are not harmed.
We made no forward or backward compatibility guarantees for versions prior to 1.0.0. However, we made every effort to ensure that new clients can read serialized data produced by library version 0.8.0 and onward.
Since version 1.0.0, there have been five new minor versions and zero new major versions of the Arrow format. Each new minor version added new features. When these new features are not used, the new minor format versions are compatible with format version 1.0.0. The new features added in each minor format version since 1.0.0 are as follows:
- Added 256-bit Decimal type.
- Added MonthDayNano interval type.
- Added :ref:`variable-size-binary-view-layout` and the associated BinaryView and Utf8View types.
- Added :ref:`listview-layout` and the associated ListView and LargeListView types.
- Added :ref:`variadic-buffers`.
- Expanded Decimal type bit widths to allow 32-bit and 64-bit types.