Hi all, I wanted to draw some attention to ARROW-11090 [1] in an effort to start getting the implementation going for temporal arithmetic kernels.
The supported operation matrix is decently large. I would like to propose that we adopt the behavior of PostgreSQL where things are at first glance ambiguous, such as this operation: SELECT DATE '2021-05-30' + INTERVAL '1' MONTH I couldn't find any documentation about this specific case, but the code is fairly straightforward and has a useful comment describing the behavior [2]. The timestamp_pl_interval will first add 1 to the month number [3], and then take the minimum of the month day (in this case 31, for the non-existent date 2021-06-31 and the latest valid day in the month (the latest valid day being 30; month day counts are encoded as a table with two rows one for leap years one for non leap years [4]) [5]. Thoughts? [1]: https://issues.apache.org/jira/browse/ARROW-11090 [2]: https://github.com/postgres/postgres/blob/master/src/backend/utils/adt/timestamp.c#L2830-L2839 [3]: https://github.com/postgres/postgres/blob/master/src/backend/utils/adt/timestamp.c#L2862 [4]: https://github.com/postgres/postgres/blob/master/src/interfaces/ecpg/pgtypeslib/dt_common.c#L14-L16 [5]: https://github.com/postgres/postgres/blob/master/src/backend/utils/adt/timestamp.c#L2874-L2876
