Data Warehousing Interview Questions and Answer Part – 6
51) What is a cube in data warehousing concept?
Cubes are logical representation of multidimensional data. The edge of the cube contains dimension members and the body of the cube contains data values.
52) What are the difference between Snow flake and Star Schema?
Star schema contains the dimension tables mapped around one or more fact tables. It is a denormalized model and no need to use complicated joins. Also queries results fast.
Snowflake schema: It is the normalized form of Star schema. It contains in-depth joins, because the tables are split in to many pieces. We can easily do modification directly in the tables. We have to use complicated joins, since we have more tables.There will be some delay in processing the query.
53) What is Dimensional Modelling?
Dimensional Modelling is a design concept used by many data warehouse designers to build their data warehouse. In this design model all the data is stored in two types of tables – Facts table and Dimension table. Fact table contains the facts/measurements of the business and the dimension table contains the context of measurements i.e., the dimensions on which the facts are calculated.
54) What are the steps involved in Database Startup?
Start an instance, Mount the Database and Open the Database.
55) What are the steps involved in Database Shutdown?
Close the Database; Dismount the Database and Shutdown the Instance.
56) What is Partial Backup?
A Partial Backup is any operating system backup short of a full backup, taken while the database is open or shut down.
What is a full backup?
A full backup is an operating system backup of all data files, on- line redo log files and control file that constitute ORACLE database and the parameter.
57) Can a View based on another View?
58) Can a Table space hold objects from different Schemes?
59) Can objects of the same Schema reside in different table spaces?
60) Do you View contain Data?
Views do not contain or store data.