Re: Oracle Transparent Gateway for DB2/400

johnimo_at_hotmail.com wrote:
>
> Hello,
>
> I have two questions: 1) We are considering using this gateway. I have been
> reading the documentation from Oracle about this particular gateway but all
> the information references to Oracle7. We are working with Oracle8.0.4 Can I
> assume that the gateway is as compitable with Oracle8 as it is with Oracle7?
>

These interworking issues are always hard to find in any documentation. I suggest you arrange for a trial period with Oracle before buying the product.

> 2) Does anybody have experience with this gateway, if so, can you tell me your
> experience, any difficulties, etcetera? I am really curious.
>

We have worked with a DB2 gateway running on a host. I can give no exhaustive evaluation of the product, but we had problems in the following areas:

1. Administration It turned out to be a bottleneck to have two or more database sites to keep in sync with administration.
2. SQL dialects You cannot use Oracle-specific SQL constructs, such as sequences, nested transactions, synonyms, rowids, etc. The latter turns out to be a problem with Forms in particular, where a record is updated by rowid, rather than by primary key. You need to switch Forms to the appropriate behaviour, thereby losing some of Forms' functionality. In some cases, you must change the application architecture to satisfy the gateway.
3. Datatypes There are diffences in datatypes between DB2 and Oracle. For instance, the DATE datatype has different ranges and scales. The DB2 TIMESTAMP datatype is seen (via DESCRIBE) as a VARCHAR datatype on the Oracle side. Differences in integral and floating numbers may lead to an application design that must be aware of the gateway.
4. Performance Using primary keys in large online applications slows down the system performance significantly. Also, splitting queries over two or more databases doesn't allow for optimization.

We ended up with an replicated database and sent the changes periodically to the host, i.e. we didn't use the gateway in online processing. Where we had to query or update a host table online, we didn't use Forms built-in functionality to do so, but rather had to code it explicitly.

Marcus Reichardt
Consultant
> Thanks, John
>
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Received on Thu Aug 13 1998 - 15:06:39 CEST