Re: Data Replication

Thanks, Joshua.

As I mentioned to Steve, warm standby / log shipping seems to be the
main feature I'm looking for.

The PITR solution you mention:  is that an improvement over regular log
shipping?  Or do I misunderstand where that fits into the system?

-Will


-----Original Message-----
From: Joshua D. Drake [mailto:jd@commandprompt.com]
Sent: 10 December 2008 17:52
To: Rutherdale, Will
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] Data Replication

On Wed, 2008-12-10 at 17:18 -0500, 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)

Correct.

> b)  PGCluster for Multi-master data replication, also 3rd party add-on
> tool, also FOSS.

Correct. Unsure of stability.

> c)  Postgres-R for multi-master data replication, appears to be a code
> fork of PostgreSQL

Not stable as far as I know.

> 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

  e) PITR which is asynchronous log shipping. This is available in all
versions >= 8.1 (foss)

  f) PostgreSQL Replicator an asynchronous replication system and a fork
of the core postgresql (see
https://projects.commandprompt.com/public/replicator)

  g) Londiste, created by Skype. Similar to Slony but easier to manage

>
> 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.

And broken but yes :)

>
> 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?

See above. Let me know if it is unclear.

> ii)  Does anybody have experience with these tools they could share?

Slony is useful if a bit difficult to manage. It is extremely flexible
however. We have several customers that user it.

Replicator is a previously closed source product. It is easy to use and
the latest version for 8.3 is in beta with 1.9 on the horizon which adds
DDL replication. We have several customers that use it.

Londiste I have played with a bit, it works but I have no production
experience with it.

> 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?
>

Planned yes, guaranteed no and it is still log shipping which means read
only slaves are out (as I recall).

Sincerely,

Joshua D. Drake



> -Will
>
>
>
>
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