Re: pg_streamrecv for 9.1?

On Wed, Dec 29, 2010 at 20:19, Gurjeet Singh <singh(dot)gurjeet(at)gmail(dot)com> wrote:
> On Wed, Dec 29, 2010 at 1:42 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>
>> On Dec 29, 2010, at 1:01 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> > Is it really stable enough for bin/?  My impression of the state of
>> > affairs is that there is nothing whatsoever about replication that
>> > is really stable yet.
>>
>> Well, that's not stopping us from shipping a core feature called
>> "replication".  I'll defer to others on how mature pg_streamrecv is, but if
>> it's no worse than replication in general I think putting it in bin/ is the
>> right thing to do.
>
> As the README says that is not self-contained (for no fault of its own) and
> one should typically set archive_command to guarantee zero WAL loss.

Yes. Though you can combine it fine with wal_keep_segments if you
think that's safe - but archive_command is push and this tool is pull,
so if your backup server goes down for a while, pg_streamrecv will get
a gap and fail. Whereas if you configure an archive_command, it will
queue up the log on the master if it stops working, up to the point of
shutting it down because of out-of-disk. Which you *want*, if you want
to be really sure about the backups.

> <quote>
> TODO: Document some ways of setting up an archive_command that works well
> together with pg_streamrecv.
> </quote>
>
>     I think implementing just that TODO might make it a candidate.

Well, yes, that's obviously a requirement.

>     I have neither used it nor read the code, but if it works as advertised
> then it is definitely a +1 from me; no preference of bin/ or contrib/, since
> the community will have to maintain it anyway.

It's not that much code, but some more eyes on it would always be good!

--
 Magnus Hagander
 Me: http://www.hagander.net/
 Work: http://www.redpill-linpro.com/