Chris --
You asked
>
> I'm currently using 7.4 and I trying find out what the value/advantage
> of upgrading to a more recent version and to which version.
>
Eventually 7.4 will not be supported (there's discussion elsewhere on how to deal with 7.3), so it would pay to move off of it well before that time (admittedly a year or more off, at a guess).
As another poster pointed out, the release notes indicate improvements that have been made, some of which are not ported back to earlier releases. These include stability improvements, often speed improvements (depending on your useage) and new features or better integration of existing ones (autovacuum seems much better in 8.2 than 8.1, and 8.3 seems even better; the integration of tsearch2 into the core in 8.3; easier quoting in stored procedures, etc.).
The jump from 7.4.x to 8.x is proving a challenge for us since we have one set of databases still on 7.4.14 (whatever the latest and greatest point release is); they will benefit from the upgrade, but the old databases accepted some bad UTF characters and the newer postgreses (postgresii ?) are stricter about bad data and reject them, so there's some clean up involved. Other than that upgrades have been relatively painless (7.4 --> 8.1.x --> 8.2 now).
HTH,
Greg Williamson
Senior DBA
GlobeXplorer LLC, a DigitalGlobe company
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