Re: [PATCH] Automatic HASH and LIST partition creation

On Wed, Jul 14, 2021 at 7:28 AM Pavel Borisov <pashkin(dot)elfe(at)gmail(dot)com> wrote:
> What do you think will the described approach lead to a useful patch? Should it be done as a whole or it's possible to commit it in smaller steps? (E.g. first part without AUTOMATIC capability, then add AUTOMATIC capability. Or with some other order of features implementation)

I would suggest that you consider on-the-fly partition creation to be
a completely separate feature from initial partition creation as part
of CREATE TABLE. I think you can have either without the other, and I
think the latter is a lot easier than the former. I doubt that
on-the-fly partition creation makes any sense at all for hash
partitions; there seems to be no reason not to pre-create all the
partitions. It's pretty straightforward to see how it should work for
LIST, but RANGE needs an interval or something to be stored in the
system catalogs so you can figure out where to put the boundaries, and
somehow you've got to identify a + operator for the relevant data
type. Tom Lane probably won't be thrilled if you suggest looking it up
based on the operator NAME. The bigger issue IMHO with on-the-fly
partition creation is avoiding deadlocks in the presence of current
inserters; I submit that without at least some kind of attempt to
avoid deadlocks and spurious errors there, it's not really a usable
scheme, and that seems hard.

On the other hand, modulo syntax details, creating partitions at
CREATE TABLE time seems relatively simple and, especially in the case
of hash partitioning, useful.

--
Robert Haas
EDB: http://www.enterprisedb.com