How you capture changes in data if the source system does not have option of storing date/time field in source table from where you need to extract the data?
The DW database can be Oracle or Teradata. The requirement here is to pull data from source system and ETL need to device a mechanism to identify the changes or new records. The source system can be a legacy system like AS400 application or Mainframe application. List out all such methods of data capture. The ETL can be Informatica, data stage or custom etl code.
If LKP on target table is taken, can we update the rows without update strategy transformation?
Yes, by using dynamic lookup
In what scenario ETL coding is preferred than Database level SQL, PL/SQL coding?
Data scrubbing process is difficult. That is, file contains date column like 20070823 but data warehouse requires date as 08/23/2007 in that case it is difficult.
What is snapshot?
You can disconnect the report from the catalog to which it is attached by saving the report with a snapshot of the data. However, you must reconnect to the catalog if you want to refresh the data.
What is the difference between data warehouse and BI?
Simply speaking, BI is the capability of analyzing the data of a datawarehouse in advantage of that business. A BI tool analyzes the data of a data warehouse and to come into some business decision depending on the result of the analysis.
What are non-additive facts in detail?
A fact may be measure, metric or a dollar value. Measure and metric are non additive facts.
Dollar value is additive fact. If we want to find out the amount for a particular place for a particular period of time, we can add the dollar amounts and come up with the total amount.
A non additive fact, for eg measure height(s) for ‘citizens by geographical location’ , when we rollup ‘city’ data to ’state’ level data we should not add heights of the citizens rather we may want to use it to derive ‘count’
What is the difference between Datawarehousing and Business Intelligence?
Datawarehousing deals with all aspects of managing the development, implementation and operation of a data warehouse or data mart including meta data management, data acquisition, data cleansing, data transformation, storage management, data distribution, data archiving, operational reporting, analytical reporting, security management, backup/recovery planning, etc. Business intelligence, on the other hand, is a set of software tools that enable an organization to analyze measurable aspects of their business such as sales performance, profitability, operational efficiency, effectiveness of marketing campaigns, market penetration among certain customer groups, cost trends, anomalies and exceptions, etc. Typically, the term “business intelligence” is used to encompass OLAP, data visualization, data mining and query/reporting tools. Think of the data warehouse as the back office and business intelligence as the entire business including the back office. The business needs the back office on which to function, but the back office without a business to support, makes no sense.
What is the difference between OLAP and datawarehouse?
Datawarehouse is the place where the data is stored for analyzing
where as OLAP is the process of analyzing the data, managing aggregations,
partitioning information into cubes for in-depth visualization.
What is fact less fact table? Where you have used it in your project?
Fact less table means only the key available in the Fact there is no measures available
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