Obiee GENERAL

Question

1. What is the most widely used ETL tool for data loading?
2.what are bridge tables?
3. explain opaque views
4. explain database Hints.
5. explain fragmented data.

Answer 1

1. What is the most widely used ETL tool for data loading?
Informatica... but this actually would depend on various factors in your project like source system, BIApps, cost, etc.
2.what are bridge tables?
these are tables helps to establish Many to many relations ships in simple words. No Database has the ability to maintain M-M relationships. but but you cant ignore M-M as world runs on it. so easiest way to achieve is to break M-M in to two 1-M relation ships. these two 1-m will be linked using a bridge table forming M-M. usually bridge tables holds only keys.
In OBIEE, you can define a bridge table by selecting Bridge table tick mark in LTS.
3. explain opaque views
Opaque view is a select statement issued to DB. Normally you load the data from source and store in Date warehouse. with Opaque view you wont maintain data in D, instead you read the data from source. means, every time you run the report obiee go to source and get the data for you.
http://download.oracle.com/docs/cd/E12096_01/books/admintool/admintool_PhysicalSetup31.html
4. explain database Hints.
DB hints are very useful to optimize performance. every DB has its own features and functions to do the same task or functionality which allows you to make a better sophisticated query.
http://download.oracle.com/docs/cd/E12096_01/books/admintool/admintool_PhysicalSetup32.html
5. explain fragmented data.
This very good if you have a huge volume of data which takes long time to retrieve the result set. you can divide the data based on criteria like city name starts with a-n in one table ,m-z in other table and read the individual tables when you run the report which runs more quickly.
http://download.oracle.com/docs/cd/E12096_01/books/admintool/admintool_SetUpAggNav.html