OBIEE Interview Questions


OBIEE Interview Questions

1-      What are Alias tables? Why they are used?

Ans: Physical Table that inherits all properties of its parent table are Alias Tables. They are important in many aspects like:

a)      For multiple use of physical table.

b)      To avoid circular join.



2-      What settings you can do in physical layer to enhance end user query response time?



Ans: For Performance Enhancement, most of the settings are performed in connection pool.

Some of the important tasks handled by Connection pool are :

a)      Updating Maximum Connection (default =10) based on : No. of concurrent users to No. of reports per dashboard. Eg. If a dashboard contains 5 reports per dashboard page & number of concurrent users are 100 then, Max. Connection will be

= 20% * (No. of concurrent users)*(No. of reports per dashboard page).



=.2*100*5 = 100



b)      You must also use separate connection pool for Aggregate Tables / Initialization Blocks / Data Tables that effect execution time of other randomly used DB tables. This also enhances overall query response time.



3- How to perform time series calculations?

Ans : Time Series Calculations are performed with measure columns (Columns in fact table) with respect to time dimensional heirarchy (make sure time dimension heirarchy is configured properly, with chronological keys set at the levels). Time Series Functions are available in functions & can be configured in Business Model & Mapping Layer.
Type of Time Series calculations you can perform are :

Ago()
Todate()
periodrolling()


4-      What operations can be performed in Business Model & Mapping Layer, that cannot be performed from physical layer.

Ans: Business Model & Mapping (Semantic) Layer is the most important layer in Metadata Repository, that task performed includes:

a)      Dimensional Hierarchy Creation.

b)      Creating New Logical Columns (Based on certain calculations).

c)       Updating Dimensional Modeling (to enhance performance).

d)      Creating Level Based Metrics (Measures).

e)      Aggregating Tables.

f)       Time Series Calculations.

g)      Fragmenting Data (Content Tab of LTS).

h)      Filtering Data (Content Tab of LTS).



5-      What are the common tasks performed in Presentation Layer?



Ans:

a)      Rename Tables / Columns.

b)      Reordering Tables.

c)       Nesting Tables.

d)      Setting Object Level / Data Level Security.

e)      Setting Variables (Session / Repository).

f)       Authentication / Authorization Settings.

g)      Manual Cache Management.



6-      What are common task performed in Analytics?

Ans: Task performed includes:

a)      Adhoc Report Creation / Modification.

b)      Dashboard Creation / Modification.

c)       Publishing Reports.

d)      Scheduling Reports.

e)      Setting KPI.

f)       Manage Web Catalog.

7-      Which utility you need to run to execute & generate Aggregate Tables in Database & Metadata Repository?

Ans:
 nqCmd.exe Utility ( available in OracleBI\Server\Bin for 10g & OBIEE_Home\Oracle_BI1\bifoundation\server\bin folder for 11g ). However run the utility through command prompt.

8-      How to open a repository, without knowing its Password?

Ans: Update NQSConfig.ini file (available in OracleBI\Server\Config folder for 10g ) Security Section & unhash (remove # - sign)  [AUTHENTICATION_TYPE = BYPASS_NQS; ]
Unfortunately - This feature is not available in 11g, however alternative option is there for changing password. Open Rpd in offline mode then File->Change Password.

9-      Which utility is used to run disconnected Analytics?

Ans:

sadis.exe available in OracleBI\Server\Bin folder.



10-    What a DBA needs to do, to enhance query response time (Performance Enhancement)?

Ans: Most of the time, it is Database which is responsible for  Query execution time. So DBA need to take corrective actions to enhance query performance. Most important task that a DBA can perform includes:

a)      Bitmap Indexing (Fact Foreign Key / Bitmap Join Index)

b)      Partitioning Dimensional Attributes (Eg. Time Key).

c)       Compressing Data.