Warren Little <warren.little at meridiascapital.com> writes:
> I need to get data migrated from a pg8.1 cluster to a pg8.2 cluster and was wondering how well slony will
> accomplish this task.
>
> The database size is about 250GB, so doing a dump and restore will take longer than the maintenance window for
> system downtime.
>
> I have read several posts on the postgres mailing lists that people recommend using slony to do major version
> upgrades, so I thought to give it a try.
>
> One of the concerns I have is regarding the limitation that slony does not support large objects, is this
> referring to the postgres LargeObject type?
>
> ie are bytea fields of significant size replicated?

Your interpretation is correct:

 - The nonsupported thing is the LOB type; it isn't replicable because
   triggers do not fire when LOBs are modified

 - BYTEA columns are replicated fine, and people have replicated
   Rather Large chunks of data in BYTEA columns.

   We, for instance, have been replicating our RT/3 database using
   Slony-I; on occasion users attach painfully large documents to
   tickets.  We've had documents (and hence tuples with BYTEA columns)
   of >50MB in size, and that has worked.

> Also, is there a guide to configuring Slony-I on an active system,
> or is the procedure the same (aside for the standard "backup all
> data before you begin") 

Yeah, the procedure is pretty well the usual...
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Christopher Browne
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