Have you ever tried to delete a few million rows from a table with several hundred milllions of rows with a DELETE statement? If yes, then you know that this is a very bad idea. With Oracle Partitioning you can do this more elegant and much faster.
Category Archives: DWH Architecture
Multi-Version Load in Data Vault
One of the advantages of Data Vault are the easy load patterns that can be used to load hubs, links and satellites. They are well documented in several books about Data Vault. But what happens if you want to load multiple versions in one batch? In this blog post, I will write about multi-version loads into a satellite table.
About Data Warehouse Design Patterns and Lazy Programmers
I’m a lazy programmer! That was one important detail I learned from Roelant Vos in his training last week. But there were many other interesting topics. A personal summary of a 3-days class about Data Warehouse Design Patterns.
Using Temporary Tables for Complex Reports
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.
My Very First “Data Warehouse”
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.
biGENiUS Generates Data Vault
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.
Data Warehouse Blueprints
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”.
Oracle Initialization Parameters for Data Warehouses
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.
Time Dimension Keys and Partitioning
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.