Re: Data Replication

Thanks very much, Steve.

The main (but not only) type of data replication activity I'm interested
in right now would be the warm standby.  Thus it appears from the
documents you showed me that log shipping is one solution currently
available in PostgreSQL.  I would want to make this work between
geographically separated machines that have TCP/IP connectivity between
them.

From what I understand from the documents so far, I can set up log
shipping using pgsql without any external packages.  There also seems to
be support for periodic backups from the primary to the warm standby.

-Will

BTW  Hope you don't mind my quoting style.


-----Original Message-----
From: pgsql-general-owner@postgresql.org
[mailto:pgsql-general-owner@postgresql.org] On Behalf Of Steve Atkins
Sent: 10 December 2008 17:50
To: PostgreSQL General
Subject: Re: [GENERAL] Data Replication


On Dec 10, 2008, at 2:18 PM, Rutherdale, Will wrote:

> Hi.
>
> I am trying to determine what kind of data replication is currently
> available in PostgreSQL.  This is for purposes of examining
> capabilities
> of PostgreSQL as compared to other RDBMSs.
>
> I attempted some searches in various areas and came up with a
> bewildering array of results but no clear answer.
>
> a)  Slony-I provides master/slave data replication (3rd party product
> but FOSS)
> b)  PGCluster for Multi-master data replication, also 3rd party add-on
> tool, also FOSS.
> c)  Postgres-R for multi-master data replication, appears to be a code
> fork of PostgreSQL
> d)  Support for data replication in core PostgreSQL engine coming
> up, as
> announced in this article in June 2008:
>
http://scale-out-blog.blogspot.com/2008/06/postgresql-gets-religion-abou
> t.html
>
> By contrast, when I search a similar question about MySQL, I get a
> clear
> answer that both master/slave and multi-master data replication are
> supported directly by the core engine.

Kinda.

> Could somebody please help me sort this out?  I would like to know
>
> i)  What is the current available support for data replication in
> PostgreSQL?

There's not really such a thing as one true replication solution. There
are a wide range of different requirements and tradeoffs. HA is
different
to load balancing is different to geographical distribution and so on.

http://www.postgresql.org/docs/8.3/static/high-availability.html covers
some of the tradeoffs of different approaches.

Log shipping, skytools and pgpool are the three main methods I can
think of that you didn't mention.

http://wiki.postgresql.org/wiki/Replication%2C_Clustering%2C_and_Connect
ion_Pooling
  has
others, and a bunch of references.

> ii)  Does anybody have experience with these tools they could share?
> iii)  Is data replication planned for an upcoming release of
> PostgreSQL,
> and if so what are the exact features and when is the release
> expected?

See http://www.postgresql.org/docs/8.3/static/warm-standby.html for
the current in-core support for log-shipping based replication.

Cheers,
   Steve


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