Daniel Kahn Gillmor | 11 Oct 21:58 2015

adding a replication node instructions update?

hey slony people--



> 3.1.4. Adding a Replication Node
> To add a node to the replication cluster you should
>     Create a database for the node and install your application schema in it.
>     createdb -h $NEWSLAVE_HOST $SLAVEDB
>     pg_dump -h $MASTER_HOST -s $MASTERDB | psql -h $NEWSLAVE_HOST $SLAVEDB

however, this step seems like it's not quite right.

in particular, this step appears to copy the master's replication
namespace into the new replication database.  This causes the subsequent
STORE NODE command to fail with a complaint that the _$CLUSTER_NAME
schema is already present.

I think if you add -N _$CLUSTERNAME to the pg_dump side of the pipeline,
then the rest of the directions should complete OK.

Is this a bug in the documentation, or have i misunderstood something?


(Continue reading)

Sung Hsin Lei | 10 Oct 05:34 2015

Slony Replication Startup Speed


I have a 10gig database on the Master which I backed up and restored on the Slave. Database activity is low. When I setup Slony replication from the Master to the Slave, it would take hours before new information from the Master would be updated into the Slave. Postgres would be also VERY slow for the first few hours. However, after the initial wait period, the Slave would update within a second or so and Postgres speed would return to normal. I'm assuming that Slony is taking time to verify the initial database integrity between the Master and the Slave. Am i right? I would like to know if there's a way to have the updates start within the first few minutes of the original setup.

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Ger Timmens | 30 Sep 16:02 2015

slony and bdr


To get slony replicating again when using postgresql bdr we'll need
primary keys added to the slony tables. At least:

ALTER TABLE _slony_cluster.sl_apply_stats ADD PRIMARY KEY (as_origin);

But there are maybe more. Can we add those PK's to the next patch ?

Kind Regards,

P.S. Using postgresql 0.9.4/bdr 0.9.2/slony 2.2.4
Mark Steben | 29 Sep 23:23 2015

upgrade slony master / slave using pg_upgrade

Good evening

Fairly simple question (I think)
Can I use the pg_upgrade contrib module to upgrade from postgres 9.2 to 9.4 without having to
re-define and re-subscribe all of the slony replicated data?  My initial pg_upgrade tests are yelling at me that some slony libraries are not found in the new 9.4 binaries:

Could not load library "$libdir/slony1_funcs"
ERROR:  could not access file "$libdir/slony1_funcs": No such file or directory

Hopefully it is just and issue of copying the slony binaries from 9.2 to the same libraries in 9.4 on master and slave, or is a re-creation necessary?  (We are running slony 2.2.3)

I did check on www.slony.info and didn't find any reference to pg_upgrade.

Thanks for your time and insights

Mark Steben
 Database Administrator
<at> utoRevenue | Autobase 
  CRM division of Dominion Dealer Solutions 
95D Ashley Ave.
West Springfield, MA 01089

t: 413.327-3045
f: 413.383-9567


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Mike James | 24 Aug 15:19 2015

Slony replication failed invalid memory alloc request size

We have a slony slave in AWS. During an Amazon maintenance, the instance was rebooted and now the daemon won't start. The log file has this error message:

2015-08-24 06:50:03 UTC INFO   remoteWorkerThread_1: syncing set 1 with 102 table(s) from provider 1
2015-08-24 06:50:33 UTC ERROR  remoteWorkerThread_1_1: error at end of COPY IN: ERROR:  invalid memory alloc request size 1970234207
CONTEXT:  COPY sl_log_1, line 97033:

I'm not sure whether this is a Postgres error or a slony error. We're running Postgres 9.3.5 and slony 2.2.1. Any help much appreciated.

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Dave Cramer | 23 Aug 23:56 2015

Dropping a node when the node is gone ?

Drop node always wants to connect to the node ??

Dave Cramer
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Tory M Blue | 14 Aug 00:51 2015

Slony multiple locations, questions concerning node ID's

Been a bit, but I'm back with a question.

I'm looking at doing a migration from one site to another and eventually have a hot warm site.

Right now I have a 5 box slony cluster at site A

Site A: Node 1 and 2 can switch/fail, nodes 3-5 are partial and can't become master.

Node 1: MASTER
Node 2: SLAVE

I have a new 5 node cluster in Site B.

Site B:  This is our default turn up, so they have the same NODE ID as Site A..

Node 1: MASTER
Node 2: SLAVE

I was really interested in Node 2 of Site A replicating to Node 1 of Site B, and then just let the other boxen in site B take their information from Node 1 of the same site.

 I think there is going to be some confusion with NODE ID's. I believe I can tell Site A that the Master of Site B is actually node 10 <whatever> and get it replicating and be able to drop NODE 10 if I needed from site A. However if I end up switching to the Master in Site B,  It won't know how to tell SITE A to kiss off,  as the NODE's in it's config will be 1,2,3,4,5, which are the same as Site A, so there would be no real way for me to clean up and or remove SITE A devices, drop node using NODE ID would be no beuno.

So I guess basically, do I have to have unique NODE ID's (think I do, but if not??). It will just require some rework for every site I bring up,  this means I have a few different configurations and or scripts to use depending on what site the cluster is in.

Is this sort of clear, murky yet you have the general idea, or holy carp Tory what are you asking?

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Steve Singer | 27 Jul 04:03 2015

Slonik API

During the slony session at the PGCON unconference some people asked 
about an API so they could manipulate slony clusters without having to 
call slonik.

I've done a draft attempt at moving slonik functionality into a library.

You can view my draft API here

A sample program that uses it might look like

        struct SlonikContext * context;

         SlonikApi_NodeConnInfo n1;
         n1.conninfo="host=localhost dbname=test1 port=5435";
         SlonikApi_NodeConnInfo ** n_list =malloc(sizeof( 
SlonikApi_NodeConnInfo *)*2);
         context = slonik_api_init_context("disorder_replica",n_list);

The idea is that you would setup a structure with the conninfo 
configuration and init your slony context.  You would then pass this 
context to the function call for the slonik command you want to call.

I'd like to get a sense of how people feel about this API.

If we like the API in general then we still need to figure out how to 
deal with error reporting.  The library still prints errors and messages 
to stdout which isn't ideal for an API.  We could either pass a file 
stream to the context or use callback functions

I haven't yet added support for try blocks but I think that would be 
straightforward to do. I also need to make slonik statically link with 
the library.

I have only done limited testing so far.  If we like this API I will 
then write wrappers to allow the Java JVM to call into libslonik and add 
some tests to the slony test framework.
David Fetter | 25 Jul 06:31 2015

Cloning an origin?


While in the best of all possible worlds, we'd have planned out a
replication strategy before we get tables whose initial sync via
"SUBSCRIBE SET" will never finish, we aren't always given that much
ability to plan that soon.

CLONE is great when you want to light an Nth node for N > 2, but
that's just adjusting an extant cluster, not creating one in the first

What stands between the state of the slony code and being able to
clone an origin node?


David Fetter <david@...> http://fetter.org/
Phone: +1 415 235 3778  AIM: dfetter666  Yahoo!: dfetter
Skype: davidfetter      XMPP: david.fetter@...

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Dave Cramer | 30 Jun 22:45 2015

how to remove an event

I managed to create a path which had a user which was wrong, then executed a subscribe set on that path.

I tried unsubscribe set but the event is still in the logs ?

Dave Cramer
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Dave Cramer | 30 Jun 19:45 2015

using slony to go from 8.4 to 9.4

I'm trying to replicate from 8.4 to 9.4

Getting the following error on the store node

could not access file "$libdir/slony1_funcs.2.2.2" This is occurring when trying to install the functions into the 9.4 node

Dave Cramer
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