On Wed, 2006-03-01 at 17:03 -0500, Christopher Browne wrote:
> Sven Willenberger wrote:
> 
> >As the subject line would indicate I am wondering about any caveats with
> >using Slony to replicate tables between an 8.0.x and 8.1.x database.
> >Naturally I would be using the latest version of slony with the support
> >for 8.1.
> >
> >The reason for this is that we have a main database that is running
> >8.0.x and is mainly data warehousing with some active querying traffic
> >-- it is fairly sizeable at this point (some 224G) so upgrading this via
> >pg_dump pg_restore will not be some minor afternoon activity. We have
> >satellite databases that are designed to offload the bulk of the queries
> >into their own copies of the certain tables maintained by the main
> >database. These "satellite" servers are going to upgraded (new hardware)
> >so I figured I would like to take advantage of the performance
> >improvements offered in 8.1.x of PostgreSQL. Will slony handle the
> >different versions of the databases and if so, are there any "gotchas"
> >of which I need to be aware?
> >
> >  
> >
> You'll need to be running version 1.1.5 of Slony-I; that is the
> now-latest release, and the first to support 8.1.x.
> 
> This was certainly an intended "use case," so it surely ought to work.
> 
> The one "grand challenge" you'll face is that getting the subscription
> going, with 224GB of data, will take quite a while, which will leave
> transactions open for quite a while.
> 
> One suggestion: You'd find it preferable, probably, to bump up the "-s"
> and "-t" options during the subscription, probably to only do a SYNC
> every few minutes.  It'll likely take well over a day for the
> subscription to complete, and having it generate a SYNC every 2 seconds
> would probably NOT be helpful when catching up after the subscription
> has been set up.

Thanks everyone for the feedback. Luckily we are not attempting to
replicate the "entire" system of 200+G but rather the heavily used
smaller tables. Most of the tables are support tables for the master
table and they are not being replicated at this time. Nonetheless, the
tuning tips are noted and should ease in the initial syncing.

Sven