Solutions for data storage?

[Leif K-Brooks]

I'm writing a relatively simple multi-user public Web application with 
Python. It's a rewrite of a similar application which used PHP+MySQL 
(not particularly clean code, either). My opinions on various Web 
frameworks tends to vary with the phase of the moon, but currently, I'm 
planning to use Quixote.

Needless to say, my application will need some kind of persistent data 
storage. The previous PHP+MySQL application uses around 1.1GB of 
storage, so something like PyPerSyst where everything is kept in memory 
is out.

I've looked at SQLObject, and it's very nice, but it doesn't provide 
certain features I really want, like the ability to store lists of 
strings or integers directly in the database (using commas in a varchar 
column or something).

ZODB is very nice, but IndexedCatalog doesn't seem to provide any 
automatic mechanisms for things like ensuring attribute uniqueness (for 
e.g. usernames). I suppose I could implement manual checking in every 
class that needs it, but it really seems like very error-prone code to 
be implementing at the application level.

My ideal solution would be an object database (or object-relational 
mapper, I guess) which provided total transparency in all but a few 
places, built-in indexing, built-in features for handling schema 
changes, the ability to create attributes which are required to be 
unique among other instances, and built-in querying with pretty syntax. 
Atop seems to come pretty close, but since it's meant to be used in the 
asynchronous Twisted environment, it doesn't provide any thread safety.

So basically, I'm wondering if there are any Python data storage 
solutions I haven't noticed that come a bit closer to what I'm looking 
for. I could live without built-in schema evolution; the querying is 
really the most important feature I want.