Re: PostgreSQL alternative to "Oracle Real Application

On Wed, 18 Jun 2003, Hubert Fröhlich wrote:

> Hello list
>
> I am working with PostgreSQL for the Bavarian Cadastral Administration.
> We want to update our WWW online services so that they can use more
> data. For that reason we want to set up an archive of geographical data
> (ca. 400GB vector data and - maybe also 4 TB of raster data) manily used
> for http services, i.e. the focus is on read operations. (although we
> have to do also some kind of replication from primary storage ) The
> system should be highly performant  and highly available. The use is
> designed mainly for OpenGIS standardized WWW applications on
> geographical data such as UMN MapServer ( > several 100000 web hits for
> geographical data alone). Yet it is not quite clear if we put the raster
> data simply in a file system or (as BLOBs) into a database.

blobs pretty much ARE just simply in a file system in Postgresql.  It's
usually better to just store the file in a file system and store the path
in postgresql with keywords etc... to search on.

> We use a lot of OpenSource software, not only PostgreSQL. Using
> OpenSource software is a major column of our IT strategy.

Smart move.  You never know what vendor X is gonna want next year for
licensing fees after all.  What starts as an affordable project can
quickly become very expensive should your license fees jump up by a factor
of 10.

> Now we have got a proposal for hard- and software for this machine which
> is based mainly on the concept of the "Oracle Real Application Cluster"
> on RedHat Linux boxes & file servers.
>
> The concept is said to offer big performance - but this concept does not
> fit into our IT strategy very well. We are a bit cautious concerning
> promises, as Oracle Real Application Cluster seems to be some kind of
> "black box" and we do not know HOW it really works.

I've heard a lot of good about RAC, but haven't used them myself.  Don't
believe promises, only benchmarks of your own design on your own data.  Is
Oracle willing to let you "test drive" the RAC solution, or do you they
insist you pay up in full to see it in operation?  If you can't test it,
assume it won't work until you can test it.  Promises are religion, proof
is science.

> What we would like to have is some alternative concept which allows us
> to use PostgreSQL on a powerful hardware to get highly performant and
> higly available database access on our terabytes.

Good thought.  Keep in mind that whatever you spend on Oracle licenses you
can spend on hardware for Postgresql, and Postgresql doesn't JUST run on
linux on X86.  It can run on IBM mainframes (with Linux), Sun Sparc
(solaris, linux or BSD), SGI Altix (up to 64 CPUs running linux) etc...

Plus, each year after that, you can buy more hardware for the cost of
yearly licensing on Oracle.

This may not be enough for some situations, but for most, it makes
Postgresql the faster option.  Plus, if you pay money for more advanced
hardware, you likely don't need hardware failover, since mainframes & big
iron unix usually have fault tolerant hardware.

> a) Does PostgreSQL have some features using a clustered hardware?

Nothing is built into Postgresql to do clustering.  There are many
different clustering / replication / failover setups out there.

www.pgsql.com sells a support contract that includes a commercial version
of rserv that works well for certain types of setups.  usogres is another
package, and there are several more.

> b) If no, what could be an alternative hardware concept ?

Big iron.  This is especially attractive if you already have big iron with
spare cycles or expansion capabilities laying about.

> Can anybody give me some advice or some hints to somebody who could help
> us a bit further, some web page ...

Do a search on google for postgresql and replication.  Plus search the
archives of the pgsql mailing lists at fts.postgresql.org and see if
anything looks good.