| From: | Tatsuo Ishii <t-ishii(at)sra(dot)co(dot)jp> |
|---|---|
| To: | josh(at)agliodbs(dot)com |
| Cc: | pgsql-performance(at)postgresql(dot)org, darcy(at)wavefire(dot)com, jd(at)www(dot)commandprompt(dot)com, sfrost(at)snowman(dot)net, herve(at)elma(dot)fr |
| Subject: | Re: PostgreSQL clustering VS MySQL clustering |
| Date: | 2005-01-24 01:30:33 |
| Message-ID: | 20050124.103033.21930526.t-ishii@sra.co.jp |
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| Thread: | |
| Lists: | 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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