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Tuesday 6 March 2012

OBIEE Best Practices in Physical Layer

In this post I am sharing some of the best practices to follow while we are in OBIEE solutions. 

1. Try to always import tables and columns into Physical layer rather than creating it 

2. This will ensure correct data types are set for each column. This is particularly useful 
    when there is confusion between DATE and DATETIME.

3. For each Physical Dimension table there should be a Primary Key and only one. For Fact 
    Tables, there is no need to create a Primary Key.

4. If only composite key is present create a single Physical key and add all the composite 
    key columns in it.

5. Minimize Opaque Views (SELECT statements) in Physical Layer.

6. Create Tables (recommended) or  Materialized views in data-warehouse instead

7. Always use Foreign Key Joins in the Physical layer. Avoid using complex joins with 
    conditions.  Complex joins are not good for performance and should be avoided. (there 
    are a few exceptions for this case when we work with Type 2 SCD)

8. Always try to use Number-Number join. This will work faster than a varchar-varchar join.

9. Avoid using CAST functions in the join expression. This will destroy the usability of the 
    Database indexes created on that column.

10. Avoid any filter conditions in the Join.

11. These filter conditions can in turn be added in the LTS (Logical Table Source) ‘Where’ 
      clause content filter or as request filter in Reports

12. Facts should not be joined . This will result in Cartesian Product leading to double 
      counting and summing.

13. Use conforming Dimensions instead

14. Connection Pool considerations (15-18)

15. Require fully qualified table names should be unchecked

16. Enable Connection Pooling should be checked

17. Execute queries asynchronously should be checked

18. Create a separate Connection Pool for Initialization Blocks

19. Keep Cache persistence time of all tables as Infinite

20. The columns used in Joins should be set to “NOT NULL”

21. The database Features tab should be set correctly with the Parameters supported by 
      your backend database.

22. If both are not in-sync then lot of processing will be done in the BI Server instead of the 
     Database. This affects Performance. Pay particular attention to Locale. (They are case-
     sensitive).Mismatch of Locale can cause the sorting to be done in OBI Server instead of 
      DB and performance take a bad hit !

23. DERIVED_TABLES_SUPPORTED in database features tab should be  checked for Oracle 
      Databases. This will ensure that Proper function shipping will happen to the DB in case 
      of TOP(N) and Rank functions

24. Create Display folders to group tables according to STAR or Releases

25. Set Different Icons on objects for each Release of the Code. This will ensure in finding 
      which entity was added in which release

26. Don’t Leave the Description field empty. Write some meaningful descriptions of the 
      object. This will help a lot in later trouble-shooting and Impact Analysis

Happy Blogging,

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