Gurjeet Singh wrote: > Hi, > > Here are a few questions that were asked by a customer, who are trying > to assess the pros and cons of using Postgres and its SR feature. I would > like to get an opinion of someone more involved with the community than me. > > .) Will Postgres support Streaming Replication from 9.0.x to 9.1.x; i.e. > across major releases. > > I am pretty sure the answer is "no, it won't", but just double-checking > with the community.
[ CC to general removed --- emailing only hackers; cross-posting is frowned upon. ] Right. > .) Is Streaming Replication supported across minor releases, in reverse > direction; e.g. 9.0.3 to 9.0.1 > > I think the answer is "it depends", since it would depend upon whether > any SR related bug has been fixed in the 'greater' of the minor releases. > > I am assuming that smaller minor release to bigger minor release will > always be supported (e.g. 9.0.1 to 9.0.3) Yes. We could mention in the minor release notes if we break streaming replication for a minor release --- or someone will tell us when we do. > .) How reliable is `pg_upgrade -c` (dry run) currently; that is, how > accurate is pg_upgrade at predicting any potential problem with the eventual > in-place upgrade. > > I'd say it is as reliable as it gets since this is the official tool > supported by the project, and it should not contain any known bugs. One has > to use the latest and greatest 'minor' version of the tool for the major > release they are upgrading to, though. Well, we make no guarantees about the software at all, so it is hard to make any guarantee about pg_upgrade either. > I'd also like to mention a piece of information that may be surprising > to some. Per Tom at a PGCon dinner, Postgres project does not promise > continued guarantee of in-place upgrades across future major releases. > Although the project will try hard to avoid having to make any changes that > may affect in-place upgrade capability, but if a case can be made that a > feature would give a significant improvement at the cost of compromising > this capability, then the in-place upgrade capability may be forgone for > that release. Doesn't surprise me --- I know a time will come when we must change the data format enough to break pg_upgrade's ability to perform major upgrades. It is not 'if', but 'when'. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
