Relatively soon we will have 9.0, and we will move with development to 9.1 (we as in: PostgreSQL community, I don't know C so I can't help developing myself, but I will at least try to keep up with changes in the ‘Waiting for' series).
There are some fabulous plans about new functionality, including security extensions, sync replication, writable cte, sql/med and a lot of other stuff. But while all of these are great, and important, I think that some of these features are rather exotic.
With this in mind, I tried to compile my own, personal, dream wishlist of features that I, personally, would love to get in Pg. These are probably not the most glamorous, or the most asked for, or most complex, or simplest or anything else “best of …". These are just things, that I would love to get to make my life happier/easier.
- concurrent reindex. Including indexes used by constraints.
- covering indexes/index only scans. Brilliant idea, and great optimization.
- concurrent pg_dump. Doesn't need explanation, does it?
- hstore in core (or some other way to get richer datatypes in plpgsql)
- ability to iterate over fields of records in plpgsql (which can be solved by above point, or differently)
Don't get me wrong – I will be happy to get writable cte, row-level security and other features. But the points above would make me most happy because they will cut the burden on day-to-day administration tasks.