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List:       slony1-general
Subject:    Re: [Slony1-general] Setting up replicating database to receive log-shipping files - how to do?
From:       Steve Singer <steve () ssinger ! info>
Date:       2016-10-20 21:09:53
Message-ID: alpine.DEB.2.11.1610201702150.11026 () opti ! atlantida
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On Wed, 19 Oct 2016, Andrew Edson wrote:

> 
> I am working on setting up a secondary machine, at another location, with roughly \
> the same structure as our primary machine here.   The current machine is running \
> Slony 2.0 (I think 2.0.7 but cannot recall for certain) against Postgres 8.4.13, \
> the newer one is running Slony 2.1.4 against Postgres 9.2.15. 
> 
> 
> The main machine uses slony to generate log-shipping files, which are then sent out \
> to other servers we maintain to feed the local database copies on them.  The new \
> remote machine is intended as a backup to this system, eventually to become a \
> replacement for the current machine.  To this end, I was asked to get the new \
> remote machine set up to both create log files, and to receive the log files we¢re \
> sending to the other machines we maintain.
> 
> 
> 
> I have managed to install Slony 2.1.4 on the new machine, and I have verified that \
> I can replicate changes input manually on the new machine.  Changes from the log \
> files being generated by the old machine, however, don¢t replicate on the new \
> system.  I believe, from what I¢ve found online, that the cause of this is the line \
> ¡set session_replication_role to replica;¢ found near the beginning of the log \
> files.  If I¢m understanding correctly, that is forcing the system to bypass the \
> triggers that Slony needs to run the replication setup.
> 
> 
> 
> Is there some setting I can change in the Slony instance on the log-shipping \
> generating machine to prevent the log files from being sent out with that line, or \
> something I can change on the receiving machine that will allow it to ignore the \
> line in question?  Or something else, perhaps, which can work to resolve this?  \
> What options do I have for getting this setup to work?  

Generally people don't generate logshipping files in a cascaded fashion. 
Can't you just send the sames files to multiple locations.

Also your missing something in your setup. You need at least 3 nodes wiht 
log shipping, the origin, a replica that slon is generating the log shipping 
files(B, which is a proper replica with a slon) and node C the machine 
receiving your logshipping files.

A-->slon->B->logshipping files--->C


You can just then also ship the files to nodes D and E

If you stripped the session replication role from the .sql files (which you 
could do with a script I guess) you could then do something like

A-->slon->B->log shipping files->C--->slon--->D

where you are actually running 2 slony clusters one with nodes A,B and one 
with nodes C,D (I guess this is what your trying to do?)

The set session_replication_role is added to the .sql files by slon in 
remote_worker.c (see archive_open) and can't be disabled without changing 
the code



> 
> 
> Thank you,
> 
> Andrew Edson
> 
> Application Software, Inc.
> 
> 
> 
> 
> 



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