On Fri, Jul 18, 2008 at 03:04:08PM +0200, Markus Schiltknecht wrote:
> Hello Chris,
>
> chris wrote:
>> Slony-I does the same, with the "variation" that it permits the
>> option of using a "candidate primary key," namely an index that is
>> unique+NOT NULL.
>>
>> If it is possible to support that broader notion, that might make
>> addition of these sorts of logic more widely useful.
>
> Well, yeah, that's technically not much different, so it would
> probably be very easy to extend Postgres-R to work on any arbitrary
> Index.
>
> But what do we have primary keys for, in the first place? Isn't it
> exactly the *primay* key into the table, which you want to use for
> replication? Or do we need an additional per-table configuration
> option for that? A REPLICATION KEY besides the PRIMARY KEY?
We have them because people are used to thinking in terms of a
"PRIMARY KEY," not because that concept is actually distinguishable
from a non-partial UNIQUE NOT NULL constraint.
While I'm a "chicken" rather than a "pig" on this project
<http://en.wikipedia.org/wiki/The_Chicken_and_the_Pig>, I believe that
covering the more general case right from the start would be a much
better plan.
Cheers,
David.
--
David Fetter <david@fetter.org> http://fetter.org/
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