What is data mart?
A data mart can contain one fact table to address one subject. In such a case,when a number of data marts are integrated to create a data warehouse, it is important that the facts in each table mean the same thing. Such facts (i.e., measures or metrics) that have the same meaning in different data marts are called conformed facts.
What are the different types of datasmarts?
– Stand–alone Data Marts : Data marts that do not interact with other data marts are called stand–alone data marts. On the other hand, data marts can be integrated to create a data warehouse.
– Multi–source Data Mart : A data mart for which the input data is obtained from multiple sources is called a multi–source data mart.
– Personal Data Mart : A data mart for use by individuals such as Chief Executive Officer (CEO), Chief Technology Officer (CTO) or Chief Financial Officer (CFO) is called Personal Data Mart.
– Operational Data Store : ODS is a database system that obtains data from different sources, consolidates it and keeps it at a single location. However, it does not have the sophistication of a data mart or a data warehouse for analytical processing. ODS is generally developed as a pre-cursor for ERP systems.
What is fact table?
A fact table is the central table that contains the measures or facts of a business process.
What is the mapplet?
Mapplet is a set of transformations that you build in the mapplet designer and you can use in multiple mappings.
What is meant by grain?
Granularity of data is a very important factor in the design of fact table. In fact table, we can represent data at different atomic levels, called grains.
What is difference between view and materialized view?
Views contains query whenever execute views it has read from base table. A view which is physically stored in a database. Materialized views allow query performance to be enhanced by precalculating costly operations.
What is surrogate key?
A system generated artificial primary key that is not derived from any data in the database. It is similar to the object identifier in an object oriented system.
What is a folder?
Folder contains repository objects such as sources, targets, mappings, transformation which are helps logically organize our data warehouse.
What is pivot?
The pivot (or rotate) operation rotates the axes of a cube to provide an alternative presentation of the data.
What is the difference between mapping and session?
Maping : It is a set of source and target definitions linked by transformation objects that define the rules for transformation. Session : It is a set of instructions that describe how and when to move data from source to targets.