Be careful about this question. What the interviewers want to know it your knowledge and experience on OLAP DSS, but many candidates missed this point, they explained their DBA experience in general, but failed to answer what is asked. To answer this question correctly, you should provide your knowledge about the characters of OLAP and DSS systems, and how you configure the database to meet the requirements.
“I have extensive DBA experience in configuring database server for both OLTP and OLAP systems. I worked on many transaction-oriented database, I also had the opportunity to setup database for decision support systems. Nowadays most of the RDBMS provide options to setup OLAP for you during installation, you simply select this option and the installation process will configure your database suitable for OLAP and DDS applications. Of course I can always change my database configuration manually when necessary. The major difference of OLAP comparing to transaction database is that OLAP requires fast data retrieval and concurrent access. Many DSS applications run very complicated queries. In general, there are every few data manipulation activities such as insert, update, and delete. Therefore in OLAP configuration I use indexes heavily to speed up data query process. Oracle’s bitmap index and materialized views are also helpful. I would also configure table partitions based on the analysis of data structure. I would design tablespaces on different data files put on different hard disks and build tables across. That would increase concurrent access and reduce I/O bottleneck. For DSS system, I may consider de-normalize the data structure and build dement ional database for reporting and BI purpose. Depending on the specific project, I may implement other options such as configuring the database cache to meet the OLAP and DSS needs.”
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