Re: real multi-master replication?

Bill Moran wrote:
> Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc> wrote:
>> Bill Moran wrote:
>>> "hubert depesz lubaczewski" <depesz(at)gmail(dot)com> wrote:
>>>> hi,
>>>> i read about some replication system for postgresql, but - as far as i
>>>> know there is none real multi-master replication system for
>>>> postgresql.
>>>> all i have seen are based on "query replication" with various "hacks"
>>>> for specific constructions (like now()).
>>>> my question is - is there any (even fully commercial) multi-master
>>>> replication system for postgresql that will work with all possible
>>>> constructs, triggers, random data and so on?
>>>> i mean - i dont want to bother with choosing to 'note' somehow that
>>>> 'this particular query' has to be replicated somehow.
>>>> i'm thinking about working solution that will allow multi-master connections.
>>>>
>>>> anything? anywhere?
>>> Have you looked at pgpool?
>> afaik pgpool is statement based and not really multimaster either ...
>
> Well, it's multi-master to the degree that all servers are read/write,
> and therefore any server can take over.

not sure I follow - pgpool will simply replay the queries to each
backend-server that are going through it.
You cannot directly write to the servers (well you can - but that will
likely cause inconsistent data) - and you have all the problems with
non-determinstic queries as well as problems of getting a node back in
sync after a downtime or connection loss.

>
> How would you define multi-master?

for true multimaster one would expect to be able to write to all the
nodes and keep the data consistent/sync or have some sort of conflict
resolution for an async solution.

Stefan