[mod_python] Persisten DB connection for passwords.

Hi,

I have built a web-site that uses a persistent DB connection as suggested 
in the FAQ to store user passwords for my web-site.

The existence of the separate connections (for each python process) is
problematic in this case, because one hit on the web-page will initialize
the password (or change it) with an SQL update and then another hit to the
same page (but on a different PID) may or may not get the lastest version
of the password with SELECT.

I understand that this is a product of the multiversion model concurrency
control (MVCC) which is generally desirable and specifically desirable for 
my web-site except for the password UPDATE and SELECT commands and the 
persistent connections I'm using with mod_python.

I've been poring over the documentaion and am still a little bit unsure of 
what the easiest way to approach this is (serializable isolation lever, 
table-level locks, row-level locks, SELECT FOR UPDATE) and where to apply 
it (during the UPDATE statement, SELECT statement, or both).  The 
problem is complicated by the fact that I can't easily test it because I 
never know when the transactions will be autocommitted and which PID my 
http get will get.  I'm looking for a nice simple solution that will work 
with this rare case (i.e. please don't suggest switching to a 
different DB, using mod_perl instead ;), etc.).

I'm hoping that someone else has tried something similar and can offer a 
suggestion or pointer (or even a snippit of SQL).

FYI the DB is Postgres-7.3 (built from source), mod_python is 3.0 (built 
from source), DBA is PoPy 2.0.11 (built from source) all living on top of 
an otherwise stock RH 9.0.

Thanks in advance,

	Stefan

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