Re: Re: [ADMIN] Oracle and Postgresql Play Nice Together on Same Computer

It depends how you have your Oracle instance configured.  If you have
it set up so that the total SGA and UGA ammount consume around 80%-90%
of total available memory, then this is obviously only going to leave
postgress with 20% or less of the total available memory.  Postgres is
also designed to take advantage of the file caching behaviour of the
OS.  The OS however is probably going to prioritize Oracle running
memory over cached file pages, and therefore I would think that
running the two together is a less than optimal configuration.  If you
are going to do it, I would make sure that you at least reduce the SGA
for Oracle down below 40% of the box's total RAM so you give
postgresql enough space to work in.  Even doing this, there is a
chance that the OS will try to cache the Oracle Tablespace files if
they are small enough, duplicating the buffering effort that Oracle is
doing, and also reducing the amount of memory for Postgresql file
cache.

All in all, I would personaly be very wary of running both together if
you are planning on doing any benchmarking.

Alex Turner
NetEconomist


On Thu, 20 Jan 2005 10:20:02 +0100, simon@2ndquadrant.com
<simon@2ndquadrant.com> wrote:
>
> Troyston Campano <troygeekdatabase@gmail.com> wrote on 20.01.2005,
> 06:03:28:
> > I am an Oracle DBA and I want do a Postgresql 'proof of concept' at the
> > large corporation where I work to test the benefits of using Postgresql in
> > our environment. I want to install Postgresql onto a "production" server
> > that currently runs Oracle. Are there any problems with running Postgresql
> > and Oracle on the same machine? I mean, I've heard that the way Sybase and
> > DB2 UDB are architected to handle memory hurts Sybase when DB2 UDB is
> > installed on the same machine as the Sybase Server (something about UDB
> > eating up all the memory and not giving it back to Sybase).
> >
> >
> >
> > Are there any issues running Postgresql and Oracle on the same
> > machine.anything special to know about memory, disk layout, and things like
> > that? I just want to make sure the two engines play together on this same
> > server. I had a hard time finding information about this via google.
> >
>
> There should be no issues running both on the same machine. Running both
> together at the same time isn't a good way of doing a benchmark
> though...
>
> I would question your intent slightly. Should it be a relative
> comparison? Or should it be an assessment of what PostgreSQL is capable
> of and whether that fits a sufficient number of your needs to make it
> worth adopting?
>
> There are many ways to structure a decision as to whether PostgreSQL is
> suitable for your (business?) needs. Which structure you choose is
> likely to prejudice your decision, one way or the other. i.e. if
> capital acquisition costs are the decising factor, then PostgreSQL
> would always win.
>
> Best Regards, Simon Riggs
>
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