Re: Large Objects and Replication question

On Dec 2, 2009, at 4:23 PM, Howard Cole wrote:

> Does anyone know of a replication solution that can handle large objects? Preferrably on a per database rather than per cluster basis.

Take a look at Mammoth Replicator: https://projects.commandprompt.com/public/replicator.

Additionally there is a list of available open-source replication solutions here:
http://wiki.postgresql.org/wiki/Replication%2C_Clustering%2C_and_Connection_Pooling

Personally I'm not aware of other solutions supporting large objects, but I'm sure there should be more of them :).

>
> Incidentally - out of interest - why doesn't Slony handle large objects?
>

Here is an excerpt from the Slony documentation:

Slony-I does not automatically propagate schema changes, nor does it have any ability to replicate large objects. There is a single common reason for these limitations, namely that Slony-I collects updates using triggers, and neither schema changes, large object operations, nor TRUNCATE requests are able to have triggers suitable to inform Slony-I when those sorts of changes take place. As a result, the only database objects where Slony-I can replicate updates are tables and sequences.
http://www.slony.info/documentation/slonyintro.html#INTRODUCTION

I'm not sure that it's up-to-date, since 8.4 has at least on truncate triggers, but still there are no triggers on large objects yet.

--
Alexey Klyukin http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc