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What is data cleaning? How can we do that?
sub_guha
- Jan 25th, 2010
Data cleaning, technically called "Data Cleansing"is a group of methods for making data more reliable and accurate. Usually companies store data in warehouses so they can make meaning out of...
Hakoonamatata
- Jul 9th, 2007
Data cleaning is a self explainatory term. Most of the data warehouses in the world source data from multiple systems - systems that were created long before data warehousing was well understood, and ...
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ETL testing
How can we do the ETL testing on Data WareHouse?
anita_09
- Sep 10th, 2009
ETL testing validates that data is transformed correctly from OLTP to data warehouse. Validating the data transformed includes following main verification points: Ensures that all expected...
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Staging and Operational Data Store
What are Staging and Operational Data Stores and what is their difference?
Why does one need staging and why does one need ODS? What will happen if they are not there? Who and how is it decided that a staging or ODS is needed? Which comes first staging or ODS?jryan999
- Feb 3rd, 2010
An Operational Data Store (ODS) is a repository of active "operational" data. It's typically used to hold data for a short period (eg. Days or weeks at most), to help the business ...
srilu1234
- Jan 19th, 2010
Stagining and operational data store are different databases.It can be one database aswell to reduce the cost to maitain two databases.Staging is the place where cleansing is done and Operational Stor...
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What is the difference between database and data warehousing?What is the main advantages of data warehousingWhat is mean by data stageWhat is the famous tools used for data warehousing?What is the architecture of data warehouisng model?
brahmiii
- Feb 28th, 2010
Database is the root of any data releted operations where as datawarehousing is a schema or process how effectively we access or utilize a database. Datawarehousing follows the star schema and snowflake schema as its basic schemas and we two other schemas also which are not much important.
sap_23
- Sep 3rd, 2009
Database: A database is used to record, retrieve, update business transactions which are occurred daily in business life. Data ware House: A data warehouse is used to record historical data, purely for analysis purpose for top management.
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Merge Dimension
What is the merge dimension?
Nicolas
- Apr 17th, 2010
Merge dimension is the action in Web Intelligence XI that allows to synchronize two or more data providers through common dimension. Once created, the merged dimension can be used as an object for rep...
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AutoSys Jobs Schedule
How can we schedule our jobs in third party tool - AutoSys?
saigarneni
- May 18th, 2010
We need to write shell script to run the job and write JIL on autosys to schedule the job
varghesebinu
- Dec 10th, 2009
Autosys is a total job scheduling solution that allows you to define the event dependencies, time schedules alerts etc making it a complete data center automation tool. An AutoSys job is any single co...
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What is the main difference between star and snowflake star schema? Which one is better and why?
bcsandip
- May 25th, 2010
Star Schema: 1. Dimension tables directly connected to Fact Table2. Contain de-normalized data3. Data modifications are very easily4. Highest flexibility5. Best performance6. Takes more memory space t...
geetu rani
- Mar 27th, 2008
STAR SCHEMA HAS fact table linked with dimension table directlywhile in snow flake schema the dimension tables can have futher hierarchies between them .it means in snow flake schema the tables are no...
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Dynamic Insert
What is Dynamic Insert?
mkm187
- Oct 5th, 2010
INSERT FIRSTWHEN SAL > 25000 THENINTO special_sal VALUES(DEPTID, SAL)WHEN HIREDATE like ('%00%') THENINTO hiredate_history_00 VALUES(DEPTID,HIREDATE)WHEN HIREDATE like ('%99%') THEN...
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Importance of SCD
How is SCD helpful in real time? Give example by taking banking project.
rummyraj
- Oct 13th, 2010
Customer dimension is a good example. Customer address and Phone number frequently changes. So you will update the customer dimension for these changes.Hence its called as SCD. There are several types though. This example is type1 SCD.
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Tracing Options available in Data Warehousing
What are the different tracing options available? Can tracing options be set for individual transformations?
joshmohit
- Nov 3rd, 2010
I am not sure if this pertains to the datawarehouse in general but we do have concept of audit dimensions. Also, dimensions with effective dating can help tracing the changes.
sraghav20
- Oct 7th, 2010
I guess, this question should be directed towards particular tools... as a concept, data warehousing would be hard pressed to have any logging...
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What is dimension modeling?
joanitah
- Mar 12th, 2011
This is a process and outcomes of modeling a logical database schemas created to support OLAP and data warehousing solutions.
Hakoonamatata
- Jul 9th, 2007
Here's a different way to look at dimensional modelling:Consider data to be a flat table for now. It would have some columns that contain numbers that need to be used in calcualtions later (e.g. b...
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Degenarated Dimension
What is the use of Degenerated dimension? Where it is used?
gargupendar
- Mar 24th, 2011
A degenerate dimension is a dimension which is derived from the fact table and doesn't have its own dimension table.Example : Receipt number is the perfect example for degenerate dimension.
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Kimball and Inmon
How anyone define the pracical difference between Kimball & Inmon?
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Editorial / Best Answer
shashk- Member Since Jul-2010 | Aug 25th, 2010
Bill Inmon's paradigm: Data warehouse is one part of the overall business intelligence system. An enterprise has one data warehouse, and data marts source their information from the data warehouse. In the data warehouse, information is stored in 3rd normal form.
Ralph Kimball's paradigm: Data warehouse is the conglomerate of all data marts within the enterprise. Information is always stored in the dimensional model.There is no right or wrong between these two ideas, as they represent different data warehousing philosophies.
In reality, the data warehouse in most enterprises are closer to Ralph Kimball's idea. This is because most data warehouses started out as a departmental effort, and hence they originated as a data mart. Only when more data marts are built later do they evolve into a data warehouse.shashk
- Aug 25th, 2010
Bill Inmon's paradigm: Data warehouse is one part of the overall business intelligence system. An enterprise has one data warehouse, and data marts source their information from the data warehouse...
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Replicate vs Broadcast
What is the difference between replicate and broadcast ?
chandana
- Sep 21st, 2011
Replicate supports the component parallelism and broadcast supports data parallelism i.e fan-out,all-to-all.
zann1
- Sep 7th, 2009
Replication moves data to a specified target, usually at a specified time, and usually is usually defined by the ETL team or DBA. Broadcast moves data to targets in the system as needed, and is usuall...
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Hyperion Essbase Dimension and Hierarchy
What difference between dimension and hierarchy>What is mean by maxl?difference between esscmd and maxl?If we are using only dense dimension in outline what will be effect of cube structure?
Sahil
- Oct 25th, 2011
Dimensions are like your lookup tables and Hierarchies forms Dimensions. Inside dimensions there exists hierarchies. Example Employee is a dimension , inside Employee dimensions there can be hierarchies such as Directors hierarchy, Managers Hierarchy and employees Hierarchy etc.,,
karna.siva
- May 20th, 2008
A dimention is nothing but a subject oriented meta data, just like hr section, employees section etc. and the hierarchy is depend on the data source, like "hour glassmodel"Account dime...
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Data Warehousing Interview Questions
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