Re: Logical replication and multimaster

On Fri, Dec 11, 2015 at 5:16 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> On 2015-12-11 18:12:55 +0800, Craig Ringer wrote:
>> On 10 December 2015 at 03:19, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> > On Sun, Dec 6, 2015 at 10:24 PM, Craig Ringer <craig(at)2ndquadrant(dot)com>
>> > wrote:
>> > > * A way to securely make a libpq connection from a bgworker without
>> > messing
>> > > with passwords etc. Generate one-time cookies, sometihng like that.
>> >
>> > Why would you have the bgworker connect to the database via TCP
>> > instead of just doing whatever it wants to do directly?
>
>> pg_dump and pg_restore, mainly, for copying the initial database state.
>
> Well, you don't want to necessarily directly connect from the bgworker,
> but from processes started from a bgworker. I guess that's where a good
> bit of the Robert's confusion originated.

That's part of it, yeah. I'm a little scared of this design. I mean,
I understand now why Craig wants to do this (thanks for explaining,
Craig!), but it seems like it's going to have a lot of the same
reliability problems that pg_upgrade does. I'm not saying there's a
better way to get the functionality, but it's pretty obvious that
depending on tools other than the server itself, and in particular
pg_dump, vastly increases the failure surface area.

--
Robert Haas
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