support libarrow 6.0.0+

[DeoLeung]

seems libarrow has remove children() in 6.0+

also a question, I need libarrow-dev to build the extension, what do I need in runtime?

can I remove it after build and use something else like libarrow(thought it doesn't exists) to reduce docker images size?

[zilder]

Hi @DeoLeung,

Thanks for reporting this. Yes, children() was labeled deprecated, and I believe fields() is supposed to serve as a replacement. But I haven't try it yet. Will fix when I get a chance.

libarrow-dev is only needed for building, libarrow should suffice for runtime. Also once you are looking to reduce the size you may want to build it from sources. Here is a building guide describing all available options. I think for parquet_fdw you only need to enable -DARROW_PARQUET and the codecs you are gonna use and disable everything else. But it may require some experimentation.