Обсуждение: Oracle and Postgresql Play Nice Together on Same Computer?

On Thu, 20 Jan 2005 00:03:28 -0500, Troyston Campano
<troygeekdatabase@gmail.com> wrote:
>
> Hello,
>
> 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.

For testing purposes there shouldn't be any problems, at least in a
*NIX environment. PostgreSQL is very undemanding and compared to
Oracle is positively minuscule (at least as far as its "installation
footprint" goes). I've run PostgreSQL, MySQL, DB2 and Oracle on the
same development machine without any issues. Of course if another
application is in constant use on a production server PostgreSQL won't
perform as well as it could.

Ian Barwick

I guess what I am concerned about *is* running on a production server more
than a test server. Basically, I'd be taking a couple applications that are
running on the Oracle database instance, building a Postgresql instance, and
migrating them to that postgresql database instance. I'm just wondering
whether it's a bad idea to run them on the same server machine in a
production environment. (So instead of having 10 applications running on
Oracle on ServerComputerA...build a new postgresql instance on
ServerComputerA that lives along with Oracle and migrating 3 of the
applications to Postgresql.

Thank you for your time!

~ Troyston Campano ~

-----Original Message-----
From: Ian Barwick [mailto:barwick@gmail.com]
Sent: Thursday, January 20, 2005 3:07 AM
To: Troyston Campano
Cc: pgsql-admin@postgresql.org; pgsql-general@postgresql.org
Subject: Re: [GENERAL] Oracle and Postgresql Play Nice Together on Same
Computer?

On Thu, 20 Jan 2005 00:03:28 -0500, Troyston Campano
<troygeekdatabase@gmail.com> wrote:
>
> Hello,
>
> 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.

For testing purposes there shouldn't be any problems, at least in a
*NIX environment. PostgreSQL is very undemanding and compared to
Oracle is positively minuscule (at least as far as its "installation
footprint" goes). I've run PostgreSQL, MySQL, DB2 and Oracle on the
same development machine without any issues. Of course if another
application is in constant use on a production server PostgreSQL won't
perform as well as it could.

Ian Barwick

On Wed, 2005-01-19 at 23:03, Troyston Campano wrote:
> Hello,
>
> 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.


The only issue you're likely to face is the one you've already
mentioned, that Oracle may be configured to use most of the memory on
the machine, and PostgreSQL, in general, relies on the OS to do the
caching for it. Since there might not be much free / cache memory on the
machine, PostgreSQL may run a bit slower than it would were it the only
thing on the machine.

However, you can always do a benchmark with Oracle running, then shut
down oracle for a few minutes and see if PostgreSQL runs any faster with
the extra memory being used by the OS to cache the dataset.

 > 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.

We currently run Oracle and Pg 7.4.6 in production on a Solaris 8 box
with no problems.  The only concern we have had is with the freakiness
of the /etc/system message queue, semaphore and shared memory settings.
  Several apps seem to consume these finite resources and most of them
quietly act strangely and lose data when these resources are depleted.
Very few applications document what resources they *really* need.

There is probably a slick way to monitor these settings and determine
the right numbers for these, but we have not found it.  Right now the
technique is "set, boot and pray."

BTW, concern with these resources is the sole reason we are hesitant to
install a slave server running 8.0 so that we can migrate.  We will be
on 7.4 for some time.

Other than that, we have had no problems with running both Oracle and Pg
together on a production machine.

On Thu, 2005-01-20 at 06:58, Troyston Campano wrote:
> I guess what I am concerned about *is* running on a production server more
> than a test server. Basically, I'd be taking a couple applications that are
> running on the Oracle database instance, building a Postgresql instance, and
> migrating them to that postgresql database instance. I'm just wondering
> whether it's a bad idea to run them on the same server machine in a
> production environment. (So instead of having 10 applications running on
> Oracle on ServerComputerA...build a new postgresql instance on
> ServerComputerA that lives along with Oracle and migrating 3 of the
> applications to Postgresql.

Have you got a spare machine you can do the testing on at first?  That
will allow you to throw big nasty queries at the server and tune it
first, before putting postgresql on the production box.

I'd recommend reading the tuning document from varlena:

http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html

And experimenting with various settings on a test box first.  My first
PostgreSQL server way back when was running 6.5.2 or so on my P-II-300
workstation with 128 Megs of ram sitting under my desk, and it ran quite
well, well enough we used it as our development / staging server for
almost a year.