New Article on XML in the Data Warehouse
January 31, 2010
IBM has released a new white paper on use cases and benefits of using XML as a data format in a data warehouse:
XML: Changing the data warehouse
The article describes cases where using XML in a warehouse can be beneficial and improve the flexibility and evolution of a data warehouse schema to react to new requirements in a simple and cost-effective manner. Typically this is not a question of either XML or relational, but a question of using the right mix of both.
I think there are at least three use cases for using DB2’s pureXML features in a warehousing environment:
- You have or receive XML documents and you want to use them in a warehouse (for reporting queries, etc.) without shredding them to relational tables. You will typically use SQL/XML queries, possibly plugged into reporting tools such as Cognos, or you can use relational views over the XML data.
- You can add XML columns to existing relational dimension tables to make these tables more flexible, especially when the number of dimensional attributes keeps increasing as a company keeps adding new products and services over time. The above-mentioned white paper elaborates on this use case.
- In some cases you may prefer to shred incoming XML documents partially or entirely to a relational warehouse schema. In that case you will use the pureXML features too, such as XMLTABLE functions to accomplish the shredding or even simple ETL-ish tasks. However, not all types of XML lend themselves to shredding, in which case you’re back to point 1. above.
If you want to dive deeper into the technical features in DB2 that support XML in a data warehouse, such as partitioning, clustering, and compression, you may want to look at the following article:
Enhance business insight and scalability of XML data with new DB2 9.7 pureXML features
A common question related to XML in a data warehouse is how to use reporting tools with XML data, or with a mix of XML and relational data. Here is an article that describes how to do this with Cognos on top of DB2 pureXML:
Create business reports for XML data with Cognos 8 BI and DB2 pureXML http://www.ibm.com/developerworks/data/library/techarticle/dm-0811saracco/index.html
And to round off the data warehouse topic, there is a two-part article on IBM InfoSphere DataStage and DB2 pureXML: