alt Hacker NewsYou can do row by row appends to a Feather (Arrow IPC — the naming is confusing). It works fine. The main problem is that the per-append overhead is kind of silly — it costs over 300 bytes (IIRC) per append.
I wish there was an industry standard format, schema-compatible with Parquet, that was actually optimized for this use case.
Creating a new record batch for a single row is also a huge kludge leading to lot of write amplification. At that point, you're better off storing rows than pretending it's columnar.
I actually wrote a row storage format reusing Arrow data types (not Feather), just laying them out row-wise not columnar. Validity bits of the different columns collected into a shared per-row bitmap, fixed offsets within a record allow extracting any field in a zerocopy fashion. I store those in RocksDB, for now.
https://git.kantodb.com/kantodb/kantodb/src/branch/main/crat...
https://git.kantodb.com/kantodb/kantodb/src/branch/main/crat...
https://git.kantodb.com/kantodb/kantodb/src/branch/main/crat...