On Tue, Feb 16, 2021 at 11:02 PM Laurenz Albe <laurenz.a...@cybertec.at> wrote: > On Tue, 2021-02-16 at 16:29 +0900, Amit Langote wrote: > > > I am +1 on allowing to override the degree of parallelism on a parallel > > > append. If "parallel_workers" on the partitioned table is an option for > > > that, it might be a simple solution. On the other hand, perhaps it would > > > be less confusing to have a different storage parameter name rather than > > > having "parallel_workers" do double duty. > > > Also, since there is a design rule that storage parameters can only be > > > used > > > on partitions, we would have to change that - is that a problem for > > > anybody? > > > > I am not aware of a rule that suggests that parallel_workers is always > > interpreted using storage-level considerations. If that is indeed a > > popular interpretation at this point, then yes, we should be open to > > considering a new name for the parameter that this patch wants to add. > > Well, > https://www.postgresql.org/docs/current/sql-createtable.html#SQL-CREATETABLE-STORAGE-PARAMETERS > says: > > "Specifying these parameters for partitioned tables is not supported, > but you may specify them for individual leaf partitions." > > If we re-purpose "parallel_workers" like this, we'd have to change this.
Right, as I mentioned in my reply, the patch will need to update the documentation. > Then for a normal table, "parallel_workers" would mean how many workers > work on a parallel table scan. For a partitioned table, it determines > how many workers work on a parallel append. > > Perhaps that is similar enough that it is not confusing. I tend to agree with that. -- Amit Langote EDB: http://www.enterprisedb.com