Re: Transaction-controlled robustness for replication

Simon Riggs wrote:
>
> On Wed, 2008-08-13 at 15:38 +0200, Markus Wanner wrote:
>
> > Simon Riggs wrote:
> > > Classification of Replication Techniques
> >
> > Thanks for your classifications. It helps a great deal to clarify.
> >
> > > Type 2 is where you ship the WAL (efficient) then use it to reconstruct
> > > SQL (flexible) and then apply that to other nodes. It is somewhat harder
> > > than type 1, but requires less infrastructure (IMHO). Definitely
> > > requires less data shipping from Primary node, so very possibly more
> > > efficient.
> >
> > What leads you to that conclusion? AFAICT a logical format, specifically
> > designed for replication is quite certainly more compact than the WAL
> > (assuming that's what you mean by "less data").
>
> Possibly, but since we are generating and writing WAL anyway that's not
> a completely fair comparison.
>
> > Which of IBM's and Oracle's products are you referring to?
>
> IBM DB2 HADR, QReplication.
> Oracle Streams 10g+, Data Guard Logical and Physical Standby
> All of which I've personally used, except for Oracle Streams10g, which I
> investigated thoroughly for a client about 4 years ago.

I think doing the WAL streaming and allowing a read-only slave is enough
work to keep Simon busy for quite some time. I don't understand why the
logical issue is being discussed at this stage --- let's get the other
stuff done first.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +