Support apache arrow

[domoritz]

It's on the roadmap but I wanted to create an issue for it so I can see when it may be supported. I'm very interested in adopting this package but need arrow support (I just need access to the binary ipc).

[jraymakers]

Whether & when I work on Arrow support will depend on the fate of this currently-deprecated part of the C API.

Based on this PR, it looks like they will remain deprecated. I'm not sure what the long-term plan is.

[jraymakers]

It seems the Arrow support in the C API has a "DEPRECATION NOTICE", which is distinct from "DEPRECATED". Apparently this means the functions are likely to change, but the functionality itself will likely be preserved. So it seems possible I could expose Arrow support using the current functions with some confidence I can preserve that support when the C API is changed.

[jraymakers]

I reviewed the Arrow support in the C API, and, while I believe I can expose it, I'm unsure whether it provides the desired functionality. In particular, I'm unsure it provides access to the binary IPC format.

For folks interested in Arrow support: What functionality is useful? What parts of the Arrow C API would you use, and what would you like that's missing from that API?

[domoritz]

I mostly need IPC which I could then read with flechette or arrow js. In most cases I'll send the arrow straight over the wire somewhere else.

Arrow seems like the ideal format for streaming data from a server to a client. I'm not sure what alternative there is so this seems like an essential functionality almost.