Re: Practical Application

From: Emir Ibrahimbegovic <emir(dot)ibrahimbegovic(at)gmail(dot)com>
To: Andrew Sullivan <ajs(at)crankycanuck(dot)ca>
Cc: pgsql <pgsql-general(at)postgresql(dot)org>
Subject: Re: Practical Application
Date: 2015-12-14 16:26:42
Message-ID: CABuViOz8wLZC0Gn=GERtJzprhckM0UZM4ifM4B5kLoZOEKzU6A@mail.gmail.com
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Yeah guys from http://2ndquadrant.com/ are good, especially if you have a
large dataset and your business depends heavily on it. But I assume if
their management wants to cut costs, they expect that their employees will
be able to handle completely new technology with not much prior experience
(first time this happened, ever)

On Mon, Dec 14, 2015 at 11:11 AM, Andrew Sullivan <ajs(at)crankycanuck(dot)ca>
wrote:

> On Mon, Dec 14, 2015 at 03:52:41PM +0000, Gene Poole wrote:
> > I'm looking for some real world documentation on the use of ora2pg to
> move from Oracle DB 11gR2 64-bit to PostgreSQL (i.e. What's the best pgsql
> version to use; Is it possible to use a exported copy of the Oracle DB to
> create a pgsql image of it; These kinds of questions).
> >
>
> The best version of Postgres to use is the latest stable version, if
> you can. The second-best version of Postgres to use is the one you
> already have in production :) If you're just doing development, it
> might be worth working against 9.5. beta instead of 9.4.x, depending
> on your deployment plans.
>
> I have used ora2pg, but last time was a couple years ago so my
> experience is stale. It did a pretty good job for me. You might find
> that there are some things you end up wanting to modify. What I found
> worked best for me was to pull the database into a schema to "stage"
> with and then select from that. (When migrating, I often find it
> better to look hard at the database schema at the same time. Data
> types in Oracle and in Postgres are not perfect matches.)
>
> Note that even if you end up modifying the underlying "real" schema,
> you need not necessarily modify your application at the same time.
> Postgres has updatable views and so on, so from the point of view of
> the application, you can leave the database unchanged. I like to use
> this feature, in fact, to do A/B testing on new versions of the
> application: the old one gets app_schema_a and the new one
> app_schema_b, so you can roll over gradually and change your schema
> without a lot of outage hassle and so on.
>
> > Does PGSQL function the same as Oracle when using Foreign Keys and
> Lookup Tables.
>
> Generally, yes. There are some differences. There is an old page at
> https://wiki.postgresql.org/wiki/Oracle_to_Postgres_Conversion that
> outlines some of them. I don't think the grammar differences have
> changed too much. The BLOB discussion is all obsolete.
>
> > This is a POC to see if we can cut costs.
>
> I'm sure you can! There are also some firms that can help with
> migration if you like.
>
> Best regards,
>
> A
>
> --
> Andrew Sullivan
> ajs(at)crankycanuck(dot)ca
>
>
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