On Tue, 14 Nov 2006, Bruce Momjian wrote:
> Your description was too detailed, but I took some of your concepts:
>
> <para>
> In clustering, each server can accept write requests, and these
> write requests are broadcast from the original server to all
> other servers before each transaction commits. Heavy write
> activity can cause excessive locking, leading to poor performance.
> In fact, write performance is often worse than that of a single
> server. Read requests can be sent to any server. Clustering
> is best for mostly read workloads, though its big advantage is
> that any server can accept write requests --- there is no need
> to partition workloads between read/write and read-only servers.
> </para>
>
> <para>
> Clustering is implemented by <productname>Oracle</> in their
> <productname><acronym>RAC</></> product. <productname>PostgreSQL</>
> does not offer this type of load balancing, though
> <productname>PostgreSQL</> two-phase commit (<xref
> linkend="sql-prepare-transaction-title"> and <xref linkend=
> "sql-commit-prepared-title">) can be used to implement this in
> application code or middleware.
> </para>
Bruce,
Continuent's uni/cluster middleware product implements this type of
clustering/load balancing. Perhaps it warrants a mention? Not sure how far
we want to get into listing external products.
--
Jeff Frost, Owner <jeff@frostconsultingllc.com>
Frost Consulting, LLC http://www.frostconsultingllc.com/
Phone: 650-780-7908 FAX: 650-649-1954
