Re: The plan for FDW-based sharding

On Tue, Mar 1, 2016 at 10:37 AM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> On Tue, Mar 1, 2016 at 10:19:45AM -0500, Robert Haas wrote:
>> > Two reasons:
>> > 1. There is no ideal implementation of DTM which will fit all possible needs
>> > and be efficient for all clusters.
>>
>> Hmm, what is the reasoning behind that statement? I mean, it is
>> certainly true that there are some places where we have decided that
>> one-size-fits-all is not the right approach. Indexing, for example.
>
> Uh, is that even true of indexing? While the plug-in nature of indexing
> allows for easier development and testing, does anyone create plug-in
> indexing that isn't shipped by us? I thought WAL support was something
> that prevented external indexing solutions from working.

True. There is an API, though, and having pluggable WAL support seems
desirable too. At the same time, I don't think we know of anyone
maintaining a non-core index AM ... and there are probably good
reasons for that. We end up revising the index AM API pretty
regularly every time somebody wants to do something new, so it's not
really a stable API that extensions can just tap into. I suspect that
a transaction manager API would end up similarly situated.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company