Subject: Re: Replication documentation addition
From: Hannu Krosing <hannu@skype.net>
To: Bruce Momjian <bruce@momjian.us>
Cc: PostgreSQL-documentation <pgsql-docs@postgresql.org>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>
In-Reply-To: <200610240420.k9O4Keq23589@momjian.us>
References: <200610240420.k9O4Keq23589@momjian.us>
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Date: Tue, 24 Oct 2006 16:29:36 +0300
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Ühel kenal päeval, T, 2006-10-24 kell 00:20, kirjutas Bruce Momjian:
> Here is a new replication documentation section I want to add for 8.2:
> 
> 	ftp://momjian.us/pub/postgresql/mypatches/replication

This is how data partitioning is currently described there

> Data Partitioning
> -----------------
> 
> Data partitioning splits the database into data sets.  To achieve
> replication, each data set can only be modified by one server.  For
> example, data can be partitioned by offices, e.g. London and Paris. 
> While London and Paris servers have all data records, only London can
> modify London records, and Paris can only modify Paris records.  Such
> partitioning is usually accomplished in application code, though rules
> and triggers can help enforce partitioning and keep the read-only data
> sets current.  Slony can also be used in such a setup.  While Slony
> replicates only entire tables, London and Paris can be placed in
> separate tables, and inheritance can be used to access from both tables
> using a single table name.

Maybe another use of partitioning should also be mentioned. That is ,
when partitioning is used to overcome limitations of single servers
(especially IO and memory, but also CPU), and only a subset of data is
stored and processed on each server.

As an example of this type of partitioning you could mention Bizgres MPP
(a PG-based commercial product, http://www.greenplum.com ), which
partitions data to use I/O and CPU of several DB servers for processing
complex OLAP queries, and Pl_Proxy
( http://pgfoundry.org/projects/plproxy/ ) which does the same for OLTP
loads.

I think the "official" term for this kind of "replication" is
Shared-Nothing Clustering.

-- 
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Hannu Krosing
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