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How data in datawarehouse stored after data has been extracted and transformed from hetrogeneous sources and where does the data go from datawarehouse.
sharuvijay
- Jan 29th, 2009
Data is stored in DW in a relational, aggregatted (if needed), denormalized fashion where the data can be easily analysed.
sixto.dsilva
- Sep 11th, 2008
Data will stored in fact's and dimensional tables, the relational database can be Oracle, Informatic or netezza, it purely depends upon the company which technology they want to go for.
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What are non-additive facts
sharuvijay
- Jan 28th, 2009
Non Additive facts cannot be aggregrated along with dimenstion in the fact table. For eg. Age, weather
vineela
- Jul 18th, 2007
Non additive facts are the facts that do not participate in arithmetic caliculations. for example in stock fact table there will be opening and closing balances along with qty sold and amt etc. but opening and closing balances were never used in arithmetic calculations.
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How do you connect two fact tables ? Is it possible ?
sixto.dsilva
- Sep 20th, 2008
As comment by lot of DWH gurus above, two fact tables can be connected only using conformed dimension, defination of conformed dimension:if one primary key of dimension is defined in two fact tables it is called conformed dimension.
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What are the possible data marts in Retail sales.?
ABHI2411
- Jan 8th, 2009
The possible Data Marts in Retail Sales can be-1) Sales-Sales Order Management and Customer related.Accounts receivables2) Purchase-Purchase Order management and Vendor related.Accounts payables3) Fin...
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What is the difference between view and materialized view
mri_sonam
- Dec 18th, 2008
ViewsA view takes the output of a query and makes it appear like a virtual table. You can use a view in most places where a table can be used.All operations performed on a view will affect data in the...
vijay
- Jul 13th, 2006
View?is a logical reference to a database table. But Meterial View is actual table and we can refresh data in time intervels. If you made any change in database table that change will effect into view but not meterialize view..
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What are the advantages data mining over traditional approaches?
mri_sonam
- Dec 18th, 2008
Generally, data mining (sometimes called data or knowledge discovery) is the process of analyzing data from different perspectives and summarizing it into useful information - information that can be ...
hussenshaik
- Sep 12th, 2008
Datamining is a process of looking information in different prospective that means, if you have data of sales of different products in different months we can find hiding data from same tables in the ...
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What is Replicate,Transparent and Linked cubes?
mri_sonam
- Dec 18th, 2008
Linked CubeA cube can be stored on a single analysis server and then defined as a linked cube on other Analysis servers. End users connected to any of these analysis servers can then access the cube. ...
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What is slicing and dicing? Explain with real time usage and business reasons of it's use
mri_sonam
- Dec 17th, 2008
The ability to move between different combinations of dimensions when viewing data with an OLAP browser/Report Browser.Multidimensional analysis tools organize the data in two primary ways: in multipl...
ucontactmadhu
- May 2nd, 2007
Hi, Slicing and Dicing is a feature that helps us in seeing the more detailed information about a particular thing. For eg: You have a report which shows the quarterly based performa...
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Maintain Dimensions - ETL or Data Entry
For a Customer or Product Dimension with 500,000 rows changing daily an ETL solution is the only sensible way forward. But surely you shouldn't ETL every single Dimension table - especially if there's over a hundred of them, and they're are static, error prone or manually enhanced? What would you advise / normally do ?
mri_sonam
- Dec 17th, 2008
If you are designing a Data Warehouse how can you rely on manual process? better way is to use ETL wherever required or else just extract and load.But you should refresh all your dimensions regularly ...
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What is the purpose of "Factless Fact Table"? How it is involved in Many to many relationship?
mri_sonam
- Dec 17th, 2008
Factless Fact Table is the fact table without having any measure (Transaction Data).The intention may vary from use but mostly its used for either Custom Reporting or Bridging. It contains only the k...
sixto.dsilva
- Oct 3rd, 2008
Best way of explaining the purpose of factless fact table is factless fact tables are the prefered method of recording evernts in a data warehouse where there is no natural numberic measurement associated with the event.
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What is the difference between Data modelling and Dimensional modelling?
mri_sonam
- Dec 17th, 2008
When data modeling, we are structuring and organizing data. These data structures are then typically implemented in a database management system. In addition to defining and organizing the data, data ...
Blueash
- Nov 15th, 2008
Modelling data storage optimized for Transactional Processing is Data Modelling.Modelling data storage optimized for Analytical Processing is Dimension Modelling.
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What are slowly changing dimensions
swathirao_829
- Dec 6th, 2008
A Slowly Chaging dimension explains changed data captures over the period of time. There r three types of slowly changing dimensions(SCD).1)Type 1 SCD: It keeps most recent updated values in the targe...
1292033
- Aug 2nd, 2007
The definition of slowly changing dimension is in its name only. The dimension which? changes slowly with time. A customer dimension table represents customer. When creating?a customer, normal assum...
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What is the business rule for writing the requirement?
sixto.dsilva
- Sep 11th, 2008
Business rule is nothging the transformation requirement which will convert the raw data into business users required presentation so that business users can query and do the analysis on the Data.
abcde
- Jun 27th, 2008
Business Rulw is nothing but a transformation needs to be applied on the dataacoording to the user requirement. e.g. in trading system notional value willbe multiplication of(fund price* shares)
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How do you load the data conditionally by run steps ?
DWH01
- Jul 8th, 2008
This depends upon how the ETL is done:If we are loading data using Informatica, the workflow jobs can be scheduled using Autosys or any other scheduler, in which the scripts could check for the condit...
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Explain the flow of data starting with OLTP to OLAP including staging ,summary tables,Facts and dimensions.
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jaggu_mandya- Member Since Jan-2008 | Jan 17th, 2008
OLTP(1)---->ODS(2)------>DWH(3)-------->OLAP(4)------------>Reports(5)------>decision(6)
1-2 (extraction)
2-3 (Transformation and here ODS is itself staging area )
3-4-5 (Use of reporting tool and generate reports)
6-decision is taken i,e purpose of datawarehouse is servedI think this is right picture
wnthanuja
- Jun 19th, 2008
Source System data ----------Extraction---------Transformation(Clenance the data according to business logics)(As dimensions)----------Takes data from the dimension tables in to fact tables using Surrogate keys---------------Load (As cubes)(In to the staging)
verma_tushar
- Mar 5th, 2008
In some of the cases Pre Stage is also a intermediate phase between the OLTP environment and actual staging area.The prestage is one where dta clensing, data profiling nad data validation takes place....
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Explain the situations where snowflake is better than star schema
DWAlchemist
- Apr 11th, 2008
A snowflake schema is a way to handle problems that do not fit within the star schema. It consists of outrigger tables which relate to dimensions rather than to the fact table.The amount of spac...
ghoshkunal123
- Feb 5th, 2008
Star schema is good for simple queries and logic. But snowflake schema is good for complex queries and logic. Snowflake schema is nothing but an extension of the star schema in which the dimension tables are further normalized to reducy redundancy. Hope this helps.
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What is a general purpose scheduling tool
rpreddy
- Mar 24th, 2008
A sheduling tool is a tool which is used to shedule the datawarehouse jobs...All the jobs which does some process are sheduled using this tool, which eliminates the manual intervension.
Pavan
- Aug 29th, 2005
The basic purpose of the scheduling tool in a DW Application is to stream line the flow of data from Source To Target at specific time or based on some condition.
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What are conformed dimensions
jaggu_mandya
- Jan 11th, 2008
In Integrated schema Design, a dimension which can be shared across multiple fact tables is called Conformed Dimension.
Sivakumar.R
- Dec 7th, 2007
Any Dimensional Table in a Schema which is Shared by Two Facts Tables are called Conformed dimensions.
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What is the datatype of the surrgate key
jaggu_mandya
- Jan 11th, 2008
It is a system generated sequence number, an artificial key used in maintaining history.It comes while handling slowly changing dimensions
ankitmohansharma
- Jan 7th, 2008
Hi all, Surrogate key is mostly a sequential number. Although it doesn't has to be. They are system-generated artificial primary key values. Typically, every row would have both a primary key and ...
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What is meant by Aggregate Factable?
Factable having aggregated calculations like sum, avg, sum(sal)+sum(comm),these are Aggregated FactableCheersPadhu
ThomasB
- Jan 4th, 2008
An aggregate fact table stores information that has been aggregated, or summarized from a detail fact table. Aggregate fact table ares useful in improving query performance. Often an aggre...
Data Warehousing Basics
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