Hi Matthias, On Wed, Mar 24, 2021 at 9:23 PM Matthias van de Meent <boekewurm+postg...@gmail.com> wrote: > On Mon, 22 Mar 2021 at 21:16, Bernd Helmle <maili...@oopsware.de> wrote: > > The patch changes IMPORT FOREIGN SCHEMA to explicitely allow partition > > child tables in the LIMIT TO clause of the IMPORT FOREIGN SCHEMA > > command by relaxing the checks introduced with commit [1]. The reason > > behind [1] are discussed in [2]. > > I should've included potentially interested parties earlier, but never > too late. Stephen, Michael, Amit, would you have an opinion on lifting > this restriction for the LIMIT TO clause, seeing your involvement in > the implementation of removing partitions from IFS?
Sorry that I'm replying to this a bit late. > > So the original behavior this patch wants to address was done > > intentionally, so what needs to be discussed here is whether we want to > > relax that a little. One argument for the original behavior since then > > was that it is cleaner to just automatically import the parent, which > > allows access to the childs through the foreign table anways and > > exclude partition childs when querying pg_class. > > Yes, but it should be noted that the main reason that was mentioned as > a reason to exclude partitions is to not cause table catalog bloat, > and I argue that this argument is not as solid in the case of the > explicitly named tables of the LIMIT TO clause. Except if SQL standard > prescribes otherwise, I think allowing partitions in LIMIT TO clauses > is an improvement overall. > > > I haven't seen demand for the implemented feature here myself, but i > > could imagine use cases where just a single child or a set of child > > tables are candidates. For example, i think it's possible that users > > can query only specific childs and want them to have imported on > > another foreign server. > > I myself have had this need, in that I've had to import some > partitions manually as a result of this limitation. IMPORT FORAIGN > SCHEMA really is great when it works, but limitations like these are > crippling for some more specific use cases (e.g. allowing > long-duration read-only access to one partition in the partition tree > while also allowing the partition layout of the parents to be > modified). FWIW, I agree that it would be nice to have this. -- Amit Langote EDB: http://www.enterprisedb.com
