Global temporary tables (or private temporary tables, if you use Oracle 18c) are a practical feature to be used for SQL queries with multiple steps, for example complex reports in a data warehouse. If you want to use them, some details must be considered.
Turn of the year is always a good time to look back in history. In this first blog post of the new year, I want to tell you the story of my very first “data warehouse” project. A not very serious blog post with some serious recommendations in the end.
A good idea when working with Data Vault is to generate the tables and load processes to avoid a lot of manual development. biGENiUS, the Data Warehouse automation tool of Trivadis, is now able to generate Data Vault objects.
Our new book “Data Warehouse Blueprints” is now available at Hanser Verlag as printed edition and e-book. Here a short overview of the book and some background information about the long history of this publication.
Ensemble modeling is a family of data modeling approaches optimized for data warehouse. Its basic idea is to break things into parts to increase flexibility and to change them independently. A group of people met in Stockholm to find the least common denominator of several ensemble modeling approaches. I had the luck to be invited to this “ensemble dinner”.
The configuration of a DWH database is different than the setting for an OLTP database. This has an impact on several initialization parameters of the Oracle database. The following list gives an overview of some important parameters that should be set correctly in a data warehouse environment.
In the physical design of a star schema, it is recommended to use surrogate keys for the primary keys of dimension tables. Except for the time dimension. In Oracle data warehouses it is common to use a DATE column as the primary key. The reason for this decision and several alternative solutions are described in this post.