A few user-level questions on Streaming Replication and pg_upgrade

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.

.) 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)

.) 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.

    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.

Thanks in advance,
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