Обсуждение: PostgreSQL to Oracle

On 3/9/07, Ezequias Rodrigues da Rocha <ezequias.rocha@gmail.com> wrote:
> Is it a simple action to convert a database from PostgreSQL to Oracle ?

Yes, relatively.

> Has someone any idea ?

There's a couple ways to do this, but I'd recommend first using
pg_dump to export schema only.

Your functions and triggers would need to be rewritten, but assuming
they're in PL/pgSQL, it's a fairly trivial task to translate them into
PL/SQL.

As far as the views and sequences are concerned, pull them out of the
pg_dump export and re-run them in TOAD, SQL*Plus, or your favorite
tool.

As far as the type goes, I'm not quite sure what you're doing with it
or how it's used, but it should also be easy to migrate.

To copy the data and table definitions, I'd use a database link (on
the Oracle side) with hsodbc connecting to your PostgreSQL system via
ODBC.

Now that my advice is done with, could you explain why you need to
move to Oracle from PostgreSQL?

--
Jonah H. Harris, Software Architect | phone: 732.331.1324
EnterpriseDB Corporation            | fax: 732.331.1301
33 Wood Ave S, 3rd Floor            | jharris@enterprisedb.com
Iselin, New Jersey 08830            | http://www.enterprisedb.com/

----- Original Message -----

From: Ezequias Rodrigues da Rocha

To: pgsql general ; PostgreSQL

Sent: Friday, March 09, 2007 12:54 PM

Subject: [GENERAL] PostgreSQL to Oracle

Hi list,

Is it a simple action to convert a database from PostgreSQL to Oracle ?

I mean a simple database with

33 tables
8 functions
31 sequencies
2 triggers
1 type
3 views

Has someone any idea ?

--
Ezequias Rodrigues da Rocha
http://ezequiasrocha.blogspotcom/
use Mozilla Firefox:http://br.mozdev.org/firefox/

On Friday 09 March 2007 13:32, Jonah H. Harris wrote:
> To copy the data and table definitions, I'd use a database link (on
> the Oracle side) with hsodbc connecting to your PostgreSQL system via
> ODBC.
>

Do you find this works well?  I've used it from some older Oracle instances
connecting back into PostgreSQL and the results I had have been flakey at
best.

--
Robert Treat
Build A Brighter LAMP :: Linux Apache {middleware} PostgreSQL

On 3/15/07, Robert Treat <xzilla@users.sourceforge.net> wrote:
> Do you find this works well?  I've used it from some older Oracle instances
> connecting back into PostgreSQL and the results I had have been flakey at
> best.

It really just depends on the data types in use... but I've never
really had anything I'd call, "flakey" happen this way.

--
Jonah H. Harris, Software Architect | phone: 732.331.1324
EnterpriseDB Corporation            | fax: 732.331.1301
33 Wood Ave S, 3rd Floor            | jharris@enterprisedb.com
Iselin, New Jersey 08830            | http://www.enterprisedb.com/

On Thu, 2007-03-15 at 16:20 -0400, Robert Treat wrote:
> Do you find [HSODBC] works well?  I've used it from some older Oracle
> instances connecting back into PostgreSQL and the results I had have
> been flakey at best.

For us too. We tried in early 2006 with Oracle 8 via hsodbc to
postgresql 7.4.6 and had several problems. From what I remember:

- Oracle complained about SQLError when using unixODBC 3.0. This
necessitated using 2.5.
http://www.ianywhere.com/developer/product_manuals/sqlanywhere/0902/en/html/dbpgen9/00000291.htm

- We had type conversion problems. I can't remember many details of
this, but I *think* they may have been text/varchar and timestamp/date.
We don't use blobs.

- It took our admins a fair bit of time to get working. It probably
didn't help that Oracle was running on AIX.

- The real nail in the coffin seemed to be that there was no way to push
predicates to the remote side. This mean that a remote relation was
materialized locally in order to join with local data and that we'd
never get reasonable performance for cross-database joins (which,
perhaps, it's not designed to do).


I'm particularly curious about this last problem.  Without pushing
predicates to the remote side, it's hard for me to imagine that HSODBC
would be terribly useful for anything but building a local warehouse.
This seems so odd that I think I must be wrong, but I couldn't find any
documentation that to support or discourage cross-database joins.  Can
someone out there enlighten me?  What's the intent for HSODBC and what
are its limitations?  Can one access remote server side functions via
HSODBC (eg, sqlplus> select col1,plpgsqlfx(col1) from remotetable)?


Thanks,
Reece

--
Reece Hart, http://harts.net/reece/, GPG:0x25EC91A0
./universe -G 6.672e-11 -e 1.602e-19 -protonmass 1.673e-27 -uspres bush
kernel warning: universe consuming too many resources. Killing.
universe killed due to catastrophic leadership. Try -uspres carter.

On Fri, Mar 16, 2007 at 10:18:56AM -0700, Reece Hart wrote:
> On Thu, 2007-03-15 at 16:20 -0400, Robert Treat wrote:
> > Do you find [HSODBC] works well?  I've used it from some older
> > Oracle instances connecting back into PostgreSQL and the results I
> > had have been flakey at best.
>
> - The real nail in the coffin seemed to be that there was no way to
> push predicates to the remote side. This mean that a remote relation
> was materialized locally in order to join with local data and that
> we'd never get reasonable performance for cross-database joins
> (which, perhaps, it's not designed to do).

DBI-Link has a way to push predicates to the remote side, but you have
to do it manually because DBI-Link is a user-space application, i.e.
it doesn't have access to PostgreSQL's planner.

Let me know if you have questions on how this works :)

Cheers,
D
--
David Fetter <david@fetter.org> http://fetter.org/
phone: +1 415 235 3778        AIM: dfetter666
                              Skype: davidfetter

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On 3/16/07, David Fetter <david@fetter.org> wrote:
> DBI-Link has a way to push predicates to the remote side,  ...

As Ezequias asked about migrating an application, I'm not quite sure
why we're discussing this.  Using HSODBC to move data permanently is
quite good assuming you have no data type issues.

--
Jonah H. Harris, Software Architect | phone: 732.331.1324
EnterpriseDB Corporation            | fax: 732.331.1301
33 Wood Ave S, 3rd Floor            | jharris@enterprisedb.com
Iselin, New Jersey 08830            | http://www.enterprisedb.com/