Re: PostgreSQL clustering VS MySQL clustering - Mailing list pgsql-performance

From Tatsuo Ishii
Subject Re: PostgreSQL clustering VS MySQL clustering
Date
Msg-id 20050124.103033.21930526.t-ishii@sra.co.jp
Whole thread Raw
In response to Re: PostgreSQL clustering VS MySQL clustering  (Josh Berkus <josh@agliodbs.com>)
Responses Re: PgPool changes WAS: PostgreSQL clustering VS MySQL clustering
List pgsql-performance
> 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.

Not sure what you mean by "most connection pooling software", but I'm
sure that pgpool behaves differently.
--
Tatsuo Ishii

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