Re: Migrating from Informix to Postgre

Thank you for your response.

I understand that it is not heterogenous.  Is it open?

Let's say, I am running a transaction in Informix and part of that
transaction has to update another database which is running on Postgre.  Is
this possible?  Informix claims that it supports heterogenous transactions
as long as other participating database servers are capable of doing so.

We were thinking of replacing servers one at a time.

Thank you for your advice.

D

-----Original Message-----
From: Bruce Momjian [mailto:pgman@candle.pha.pa.us]
Sent: Friday, October 18, 2002 11:51 AM
To: Dinesh Anchan
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] Migrating from Informix to Postgre


Dinesh Anchan wrote:
> Hi Everyone,
>
> I am a first timer in this forum.
>
> We are currently using Informix and looking for a more economic database
> solution(combination of Linux and Opensource database).  We currently have
5
> database servers; 1 running on Sun E450(4 cpu), 2 on Sun E420(4 cpu), 1 on
> Sun E250 and 1 on Netra T1, with database sizes 30 GB, 12 GB, 12GB, 15GB,
> 2GB respectively.  Databases on E420s are replicated between them.  There
> are at least 10 tables which hold more than 75 million records and
> fragmented accross different tablespaces. They have indexes and used
> extensively in DSS type and as well as OLTP type of queries.
>
> I went through lot of material in the discussion group but could not find
a
> straight forward answer for the following questions.  I would greatly
> appreciate if someone can share your experience with Postgre.
>
> 1. How comfortably Postgre can support these databases( with respect to
> volume)?

No problem.  We have Oracle/Informix folks migrating all the time.

> 2. How reliable and what kind of replication Postgre provides? Is it log
> based or transaction based?

Only single-master replication available in /contrib/rserv and
/contrib/dbmirror.  We are working on multi-master for a later release.

We also don't have point-in-time recovery yet, but that will be in 7.4,
due out in about 6 months.

> 3. Does it support table fragmentation accross multiple tablespaces?

No.

> 4. Does it support raw devices?

No.  We feel the performance improvement on raw devices is minimal.

> 5. I have read that it is transactional. But is it heterogeneous?  Can I
> update multiple databases in multiple database servers of different family
> (like informix, MySQL etc) in a single transaction?

You can only update one database per session connection.  We do have
schemas in 7,3, though.  We are in 7.3 beta now.

> 6. How is the performance?

Very similary to Informix/Oracle;  faster for some things, slower for
others.

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