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()
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.
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.
