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Date: Wed, 7 Dec 2011 15:36:16 +0100
Subject: Re: [GENERAL] Convert / Migrate From Oracle 11gR2 To PostgreSQL ? On
	CentOS 5.7 x86_64
From: "Tomas Vondra" <tv@fuzzy.cz>
To: "Gene Poole" <gene.poole@macys.com>
Cc: pgsql-novice@postgresql.org, pgsql-general@postgresql.org,
	pgsql-admin@postgresql.org
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On 7 Prosinec 2011, 15:13, Gene Poole wrote:
> This has to do with my personal home environment.
>
> I'm running Oracle 11gR2 DBMS with 4 instances using a single home
> directory.  For each of the instances I'm using LVM file systems with 1=
0
> logical volumes defined (/dbmsu00 used for the install and /dbmsu01 - u=
09
> for the required files created using the DBCA utility). A single LISTEN=
ER
> created using the NETCA utility.

Not sure why you're doing this, but you can do something similar with
PostgreSQL. Running four clusters using the same set of binaries is not a
big deal.

> I chose Oracle because back in the dark ages I was a Oracle DBA when
> Oracle 7.3 was current. I've been told that it's OK to download and use
> the Oracle DBMS in a noncommercial environment for a limited time - wel=
l
> it's reached the end of that time.  I can't use the free Oracle XE beca=
use
> the database size limitations (4 GB).

Although this is a PostgreSQL list, I'll point out the limit is 11GB with
the current Oracle XE version (11g).

> Based upon what I've read and seen, the best choice for me is PostgreSQ=
L
> Community Edition. What I need is advice, documentation, and informatio=
n
> on how to take the above and move it from Oracle to PostgreSQL along wi=
th
> updating my JBoss 6.0 environment so it has access to the PostgreSQL
> databases/instances?  Can someone supply me with some direction?

PostgreSQL Community Edition? What is that? Do you mean sources that are
available for download from postgresql.org?

Switching the database in the AS is not a big deal - there's usually a
connection pool, so you need to add PostgreSQL JDBC driver and change the
config.

Porting the application is usually much harder, especially if you use
features that are available on Oracle only (or if you're hurt by some
Oracle-ism). If you're using native SQL, PL/SQL, etc. you'll have to
rewrite that. The complexity really depends on how your application is
coded, it's impossible to judge this.

Anyway, the simplest thing you can do is to give it a try. Install
PostgreSQL on a development environment and try to run the application.
It'll probably fail for some reason - fix the issue and repeat.

There are tools to make the switch easier - e.g. orafce package that
provides some compatibility features.

Tomas