On 8 December 2017 at 11:23, Robert Haas <robertmhaas@gmail.com> wrote:
> On Thu, Dec 7, 2017 at 4:57 PM, David Rowley
> <david.rowley@2ndquadrant.com> wrote:
>> That's true, but is it worth inventing/maintaining an ATTACH syntax
>> for that? It's not a very common case that multiple matching indexes
>> existing. If it is worth it, do we need DETACH at all?
>
> I think it is totally worth it. A little piece of extra DDL syntax
> isn't that really costing us anything. Your proposed approach
> probably still has obscure failure cases - e.g. I bet the
> deadlock-avoidance logic in parallel restore won't know about the
> dependency on a seemingly-unrelated object. Also, the use of a
> seemingly-useless REPLACE syntax in every dump file will probably
> confuse at least a few users, and maybe a few developers, too. I
> think there is considerable value, both for the system and for the
> humans who use it, in having something that has *exactly* the
> semantics we want rather than *almost* the semantics we want.
>
> I suppose if we want to get cute, we could have ONLY the ATTACH
> syntax; if you attach an index for a partition that already has an
> index attached, that could mean attach to the new one instead of the
> old one (i.e. replace). But I would just add support for both ATTACH
> and REPLACE and call it good.
ATTACH/REPLACE sounds fine. My objection was more about the
DETACH/ATTACH method to replace an index.
--
David Rowley http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
