Re: Remove mention in docs that foreign keys on partitioned tables are not supported

On 2018-Jun-05, Amit Langote wrote:

> On 2018/06/05 16:41, Ashutosh Bapat wrote:
> > On Tue, Jun 5, 2018 at 1:07 PM, Amit Langote
> > <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> >> On 2018/06/05 1:25, Alvaro Herrera wrote:
> >>> In the meantime, my inclination is to fix the documentation to point out
> >>> that AFTER triggers are allowed but BEFORE triggers are not.
> >>
> >> Wasn't that already fixed by bcded2609ade6?

Ah, yes, so it's already OK.

> > Thought correct that suggestion is problematic for upgrades. Probably
> > users will create triggers using same function on all the partitions.
> > After the upgrade when we start supporting BEFORE TRIGGER on
> > partitioned table, the user will have to drop these triggers and
> > create one trigger on the partitioned table to have the trigger to be
> > applicable to the new partitions created.
>
> Hmm yes, maybe there is scope for rewording then.

Reading that subsection in its entirety, I'm not sure how to do better
-- it's all about restrictions that currently exist and we think we
could do better in the future, with the exception of the one about an
UPDATE/DELETE not seeing the updated version after a row migrating to
another partition. One idea would be to split it into its own list of
issues; something like:

"The following limitations apply, and might be lifted in the future:
- no way to create exclusion constraint
- foreign keys cannot refer to partitioned tables
- BEFORE row triggers are not supported

The following caveat applies to partitioned tables:
- When an UPDATE causes a row to move ..."

In other words, make a distinction of things we expect to change soon
(which might be too optimistic), vs. others we don't expect to change.

Or we could leave it alone; any behavior change would be called out in
the future version's release notes anyway. This is what I propose.

--
Álvaro Herrera https://www.2ndQuadrant.com/
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