Re: PostgreSQL clustering VS MySQL clustering

Tatsuo,

> I'm not clear what "pgPool only needs to monitor "update switching" by
>
> *connection* not by *table*" means. In your example:
> > (1) 00:00 User A updates "My Profile"
> > (2) 00:01 "My Profile" UPDATE finishes executing.
> > (3) 00:02  User A sees "My Profile" re-displayed
> > (6) 00:04  "My Profile":UserA cascades to the last Slave server
>
> I think (2) and (3) are on different connections, thus pgpool cannot
> judge if SELECT in (3) should go only to the master or not.
>
> To solve the problem you need to make pgpool understand "web sessions"
> not "database connections" and it seems impossible for pgpool to
> understand "sessions".

Depends on your connection pooling software, I suppose.  Most connection 
pooling software only returns connections to the pool after a user has been 
inactive for some period ... generally more than 3 seconds.  So connection 
continuity could be trusted.

-- 
Josh Berkus
Aglio Database Solutions
San Francisco