I'm also supportive of having a small vendorable C/C++ "Arrow middleware" that provides:
* Schemas and types * Columnar data structures and minimal APIs to build them and iterate over them * C data interface * Minimal validation (at the level of Validate but not ValidateFull) I don't think it's going to be practical to try to refactor parts of the existing Arrow C++ core to be vendorable since there are many features / requirements (e.g. an extensible buffer and device API) that these C++ classes include that aren't needed in this limited-feature middleware library. This also relates to the "Improving Arrow's database support" project that David Li raised some time ago [1]. If we want to encourage database driver libraries to add new APIs that emit the Arrow C interface, we need to make it easier to generate the C interface without requiring a new library dependency. [1]: https://lists.apache.org/thread/gnz1kz2rj3rb8rh8qz7l0mv8lvzq254w On Mon, May 30, 2022 at 11:31 AM Jonathan Keane <jke...@gmail.com> wrote: > > Thanks for working on this. I've heard people asking about something > like this from a number of different fronts on top of the obvious use > case in geoarrow | other geospatial libraries. I think a minimal piece > of Arrow that other packages could depend on without needing to bring > in all of arrow would be super valuable in building the bridges we > want across other systems. > > Do you have any (design) documentation that describes the scope of > what you're thinking? I know there have been others floating around > [1] [2] that were in a similar spirit. > > A few more questions I hope will spark more conversation: How do the > header files you linked in [3] overlap with these other efforts? Are > those headers something we could|should "just" PR into apache/arrow > and write up how to use them? If not what is the work to make them so > that they could be (the answer of course could be design something > else entirely and PR that!)? > > [1] https://github.com/paleolimbot/narrow > [2] https://paleolimbot.github.io/narrow/articles/why-narrow.html > [3] > https://github.com/paleolimbot/geoarrow-cpp/tree/main/src/geoarrow/internal/arrow-hpp > > -Jon > > -Jon > > > On Wed, May 25, 2022 at 9:29 AM Dewey Dunnington <de...@voltrondata.com> > wrote: > > > > I'm writing to gauge interest in a set of helpers in C and/or C++ for > > reading/exporting Arrow C Data interface structures. My use-case is > > building Arrow geospatial support in R [1], and while the set of helpers > > I've been using [2] has served the purpose of me writing about the > > opportunities for Arrow + geospatial [3], I would like to rewrite the > > prototype based on something developed by/with the Arrow community. > > > > Does a set of C/C++ helpers for Arrow C Data interface structures already > > exist? *Should* it exist? > > > > If it doesn't, what should the name/scope of that library be? The names > > 'nanoarrow', 'narrow', 'sparrow', and 'arrow-hpp' have all surfaced in my > > limited discussion of this so far. For the purpose of starting the > > discussion, I'll posit that the library should include helpers to > > allocate/destroy C Data interface structures, a schema metadata > > encoder/decoder, validation of a schema/array pair, and something like the > > ArrayBuilder C++ class. > > > > [1] https://lists.apache.org/thread/yb7p9wpg3k128njskhwj9j788opb67g7 > > [2] > > https://github.com/paleolimbot/geoarrow-cpp/tree/main/src/geoarrow/internal/arrow-hpp > > [3] > > https://docs.google.com/document/d/1A6e3XCerjhXVFHBDaoAlBBNFb2HG4RB9SVRpuBru7E4/edit?usp=sharing
