On 2020-Jan-02, Kohei KaiGai wrote: > 2020年1月2日(木) 12:16 Alvaro Herrera <alvhe...@2ndquadrant.com>: > > > > I think this would need to preserve the notion of multi-table truncates. > > Otherwise it won't be possible to truncate tables linked by FKs. I > > think this means the new entrypoint needs to receive a list of rels to > > truncate, not just one. (Maybe an alternative is to make it "please > > truncate rel X, and be aware that relations Y,Z are also being > > truncated at the same time".) > > Please check at ExecuteTruncateGuts(). It makes a list of relations to be > truncated, including the relations that references the specified table by FK, > prior to invocation of the new FDW callback. > So, if multiple foreign tables are involved in a single TRUNCATE command, > this callback can be invoked multiple times.
Yeah, that's my concern: if you have postgres_fdw tables linked by FKs in the remote server, the truncate will fail because it'll try to truncate them in separate commands instead of using a multi-table truncate. > > Looking at apache arrow documentation, it doesn't appear that it has > > anything like FK constraints. > > > Yes. It is just a bunch of columnar data. > In Apache Arrow, no constraint are defined except for "NOT NULL". > (In case when Field::nullable == false, all the values are considered > valid date.) OK, I suppose that means there are no concerns such as what I mention above. -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
