Re: logical changeset generation v3 - comparison to Postgres-R change set format

Hannu,

On 11/17/2012 03:40 PM, Hannu Krosing wrote:
> On 11/17/2012 03:00 PM, Markus Wanner wrote:
>> On 11/17/2012 02:30 PM, Hannu Krosing wrote:
>>> Is it possible to replicate UPDATEs and DELETEs without a primary key in
>>> PostgreSQL-R
>> No. There must be some way to logically identify the tuple.
> It can be done as selecting on _all_ attributes and updating/deleting
> just the first matching row
> 
> create cursor ...
> select from t ... where t.* = (....)
> fetch one ...
> delete where current of ...

That doesn't sound like it could possibly work for Postgres-R. At least
not when there can be multiple rows with all the same attributes, i.e.
without a unique key constraint over all columns.

Otherwise, some nodes could detect two concurrent UPDATES as a conflict,
while other nodes select different rows and don't handle it as a conflict.

Regards

Markus Wanner