Format Versioning

Feature Flags

As the table format evolves, new feature flags are added to the format. There are two separate fields for checking for feature flags, depending on whether you are trying to read or write the table. Readers should check the reader_feature_flags to see if there are any flag it is not aware of. Writers should check writer_feature_flags. If either sees a flag they don't know, they should return an "unsupported" error on any read or write operation.

Current Feature Flags

Flag Bit	Flag Name	Reader Required	Writer Required	Description
1	FLAG_DELETION_FILES	Yes	Yes	Fragments may contain deletion files, which record the tombstones of soft-deleted rows.
2	FLAG_STABLE_ROW_IDS	Yes	Yes	Row IDs are stable for both moves and updates. Fragments contain an index mapping row IDs to row addresses.
4	FLAG_USE_V2_FORMAT_DEPRECATED	No	No	Files are written with the new v2 format. This flag is deprecated and no longer used.
8	FLAG_TABLE_CONFIG	No	Yes	Table config is present in the manifest.
16	FLAG_BASE_PATHS	Yes	Yes	Dataset uses multiple base paths (for shallow clones or multi-base datasets).

Flags with bit values 32 and above are unknown and will cause implementations to reject the dataset with an "unsupported" error.