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Dimensional modelling is again sub divided into 2 types.
a)Star Schema - Simple & Much Faster. Denormalized form. b)Snowflake Schema - Complex with more Granularity. More normalized form.
cyberdiptikanta
- Jun 26th, 2010
Star Schema is performance wise better than Snow Flake Schema. As Star schema uses denormalise tables, so there will be less no of join as compared to Snow flake Schema.RegardsDiptikanta
shady2pac
- Oct 19th, 2008
Is not star schema better performance wise (querying) as it has less no of join due to denormalized structure? Please clarify
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Data Vaidations
What various validations do you perform on the data after extraction?
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Please list out the versions of datastage Parallel , server editions and in which year they are realised.
srilaja
- May 19th, 2010
About DataStage Product- DataStage was conceived at company called VMark that developed two notable products: UniVerse database and the DataStage ETL tool in first half of 1996.- VMark acquired UniDat...
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Delete Dataset
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Datastage Standards
What are the datastage standards to be considered?
Saibal Samaddar
- May 4th, 2010
Naming conventions, especially for DataStage Project categories, stage names, and links.
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How do you hide the log files for particular job?
nikhilanshuman
- Apr 8th, 2010
There is a parameter called RTLogging and ORLogging in DSParams file for every project.The default value is :RTLogging=1ORLogging=0 If you change the value to following in DSParams file:RTLogging =0 ORLogging=1 then the log will not appear in Datastage Director.
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What r XML files and how do you read data from XML files and what stage to be used?
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Server Connection
How to connect to the server in datastage?
nikhilanshuman
- Mar 22nd, 2010
Check my answers at the following link:http://www.geekinterview.com/question_details/58767
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How and where do we use or integrate Java with Datastage?
nikhilanshuman
- Mar 22nd, 2010
Java can be integrated into Datastage using JavaPack.There are two stages which are come in javapack :a) JavaClient : It is used for Sources or targets.b) Java Transformer :It is used for processing row by row. Both stages allow to use the Java Classes in your datastage jobs.
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How do you create a sequencer in datastage parallel extender
nikhilanshuman
- Mar 22nd, 2010
First thing,it is "sequence".Sequencer is an activity in the Datastage sequence.Steps to Create a sequence:a) Go To Menu.In the Menu,select File->New.b) In the window that appears,select ...
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IS there any DEFAULT HOST NAME for Data Stage SERVER & DATA STAGE PARALLEL....
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BASIC Transformer and NORMAL Transformer
What is the Exact difference between BASIC Transformer and NORMAL Transformer?When we will go for BASIC Or NORMAL Transformer?
nikhilanshuman
- Mar 19th, 2010
Difference: - A Basic transformer compiles in "Basic Language" whereas a Normal Transformer compiles in "C++".- Basic transformer does not run on multiple nodes wheras a Normal Tra...
Abhijain
- Sep 19th, 2008
The basic transformer stage is similar in appearance and function to the Normal Transformer Stage. Basic transformer stage can only be used for SMP(Symmetric Multiprocessors) systems and not for MPP(Massively Parellel Processing) system or clusters systems.
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If i run the job first 10 times there is no time variation in job execution.In same way i run the job for 100 times it takes 10 times extra time.what is the solution for it?
nikhilanshuman
- Mar 19th, 2010
The solution is to check for any bottlenecks. Try running the job for two or three more times after certain intervals and take performance statistics. If the performace is still slow then try optimizing the jobs.
nikhilanshuman
- Mar 19th, 2010
Depends on the runtime environment. Sometimes on the datastage server many processes are running at the same time. Sometimes the server might be lacking enough resources required for the job. Th...
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Where the datastage hash files are stored when they are created.
nikhilanshuman
- Mar 19th, 2010
There are two ways of specifying where the Hash Files will be created.a) Account : This is generally the project name.If this is selected,the Hash file will be generated in the hash file path specific...
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Datastage Nodes and CPUs
Please Give Me some small Notes on Nodes and CPUs. I have one question when i am using 4 nodes and 5 CPUS how many Processors will be going to execute. Please help me in this...
nikhilanshuman
- Mar 19th, 2010
Assignment of nodes and processes to CPUs is totally dependent on the Operating System. It depends on many criterias like how the processes are scheduled to be run.Which processor has free cycles avai...
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Use of Terminator Activity
What is the Use of Terminator Activity in Datastage server Jobs?
nikhilanshuman
- Mar 19th, 2010
The terminator activity is used to terminate/abort a job in particulat conditions.user can define his own flow to the terminator activity.
Abhijain
- Sep 19th, 2008
A terminator stage can be used in a job sequence to ensure that the sequence is stopped cleanly if certain situations arise. You can have multiple terminator activities and can place them anywhere in ...
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How are SQL's in one transactions written in DS. I mean open a transaction , insert, update, delete, close transaction.thanks,Chandra
nikhilanshuman
- Mar 18th, 2010
Datastage does not necessarily write all records in one transaction.For example : For OCI stage,following Environment variables are set in the datastage administrator :APT_ORAUPSERT_COMMIT_ROW_IN...
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Datastage Parallel Extender
How to extract data from source to staging area using datastage parallel extender?
nikhilanshuman
- Mar 18th, 2010
Design your job as per the requirement.If the source is a sequential file,use a sequential file stage. If the source is a table, use database stages like OCI,DRS,ODBC etc...Use a transformer to ...
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What are the datastage strings?
nikhilanshuman
- Mar 18th, 2010
In datastage , "string" is the datatype of a column.When you create a column,you get "String" as one of the options along with other datatypes.Also,this option is presen...
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Datastage Server Outer Join Facility
How to get outer join facility from Datastage Server?
nikhilanshuman
- Mar 18th, 2010
In server jobs,you can use "Merge Stage" to perform outer joiins.In parallel job you can use Lookup stage,Join stage and Merge stage.Lookup stage and Merge stage have limitations in performing joins.E.g.-- In lookup stage,left outer join can be performed.(Also,inner join)
DataStage Interview Questions
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