Re: WIP partial replication patch

Tom Lane írta:
> Boszormenyi Zoltan <zb(at)cybertec(dot)at> writes:
>
>> attached is a WIP patch that will eventually implement
>> partial replication, with the following syntax:
>>
>
> This fundamentally cannot work, as it relies on system catalogs to be
> valid during recovery.

Just like Hot Standby, no? What is the difference here?
Sorry for being ignorant.

> Another rather basic problem is that you've
> got to pass system catalog updates downstream (in case they affect
> the tables being replicated) but if you want partial replication then
> many of those updates will be incorrect for the slave machine.
>

Yes, it's true. But there's an easy solution to that, querying
such tables can be forbidden, we were talking about truncating
such excluded relations internally. Currently querying exluded
tables are allowed just to be able to see that DML indeed doesn't
modify them. As I said, ATM it's only a proof of concept patch.

> More generally, though, we are going to have our hands full for the
> foreseeable future trying to get the existing style of replication
> bug-free and performant. I don't think we want to undertake any large
> expansion of the replication feature set, at least not for some time
> to come. So you can count on me to vote against committing anything
> like this into core.
>

Understood.

Best regards,
Zoltán Böszörményi