scovich commented on issue #7870: URL: https://github.com/apache/arrow-rs/issues/7870#issuecomment-3038869064
> I think an important usecase for `VariantBuilder` is to convert a column of an existing type (e.g. json strings, ints, etc) into a column of varaint values. > Maybe in addition to the `metadata` and `values`, `VariantBuilder` itself should store the offsets of each of the created variants 🤔 ... that could work, but only if it _also_ creates one metadata dictionary per variant value and tracks _those_ offsets as well: > The one thing `VariantBuilder` _does_ provide is the handling of separate metadata + value buffers. But that just proves the current "append as many values as you like" API is incorrect -- each top-level variant value in a column of variant values needs its own metadata value -- not one aggregate metadata value for the whole column. ... at which point it's no longer meaningful to provide a `finish` method. Instead, an `into_parts` method would consume `self` and return all four building blocks, which a caller could then assemble into a `StructArray` of `BinaryArray`. Careful tho -- `BinaryArray` uses `i32` offsets while variant uses `u32`! -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@arrow.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
