Thread: Migration from OracleDB to Postgres

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Sivadas.M@cognizant.com wrote:
> We, at Cognizant Technology Solutions, India looking for changing one of our applications backend from
> OracleDB to Postgres.
> So requesting you to kindly guide us with your thoughts to appraise this change, currently our
> application backend is using Oracle DB, and storing data volume of 25 plus million XML records.

Welcome.

> Existing application on Oracle Database does the following activities. (Approx overall usage % in
> bracket)
> 
> All CRUD operations on XML data performed using XPATH criteria - to identify a XML record, includes
> ·         XML Select (70 %)
> ·         XML Update ( 20 to 30 % )
> ·         XML Delete ( 5 % )
> ·         XML Create(done at application) and Insert  (30%)
> a.       New records insertion from Application
> b.      Bulk upload /ETL insertion of 25million records – mostly onetime initial activity.
> 
> 
> However If we go for a DB change with Postgres DB, can we able to do the above operations with a good
> performance and less code changes to existing platform. Could you kindly provide us your thoughts.

There is support for XML in PostgreSQL database, but I'd guess that there is more
functionality implemented in Oracle.  For starts, XML is stored as a plain string
in PostgreSQL, which will probably make inserts and selects faster, but slow down
things like XPath queries.

I'd say that it depends on how heavily you need to manipulate XML in the database.
You'll probably have to rewrite SQL that manipulates XML in the database, since the
functions seem to be different.

> Also -
> Regarding License, Can we use BSD version for commercial purpose and any third party support can you
> name it and their fees.

PostgreSQL is free, you can use it for any purpose you want.

There is a list of companies that provide professional support:
http://www.postgresql.org/support/professional_support/
The support provided by the mailing lists is for free.

Yours,
Laurenz Albe