On Tue, Jun 6, 2023 at 03:08:50AM +0000, fujii.y...@df.mitsubishielectric.co.jp wrote: > > I've seen this message. But introduction of new built-in function will break > > requests to old servers only if this new function is used in the request > > (this > > means that query changes). However, this patch changes the behavior of old > > queries, which worked prior to update. This seems to be different to me. > > You are right. > However, for now, partial aggregates pushdown is mainly used when using > built-in sharding in PostgreSQL. > I believe when using built-in sharding in PostgreSQL, the version of the > primary node server and > the version of the remote server will usually be the same. > So I think it would be sufficient to include in the documentation a note > about such problem > and a workaround for them.
I agree that this feature is designed for built-in sharding, but it is possible people could be using aggregates on partitions backed by foreign tables without sharding. Adding a requirement for non-sharding setups to need PG 17+ servers might be unreasonable. Looking at previous release note incompatibilities, we don't normally change non-administrative functions in a way that causes errors if run on older servers. Based on Alexander's observations, I wonder if we need to re-add the postgres_fdw option to control partial aggregate pushdown, and default it to enabled. If we ever add more function breakage we might need more postgres_fdw options. Fortunately, such changes are rare. Yuki, thank you for writing and updating this patch, and Alexander, thank you for helping with this patch. -- Bruce Momjian <br...@momjian.us> https://momjian.us EDB https://enterprisedb.com Only you can decide what is important to you.
