how many datamarts we will use in real time project and when
will use the datamart?pls send the replay early
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Answer / madhu tallapaneni
For example: dB every branch have each mgr
Manager
Reliance comm.
Reliance Group : manager Top Level mgr(TLM)
Reliance power details of below
sales
Manager customer
Reliance Fresh TLM needs employee
period
` order
Input
Explanation of above example: Reliance group with some there branches and every branch have one manager. And for all this manager one Top level manager (TLM) will be there. And TLM needs the details of list shown above for analyze.
Bottom level
For above example how ETL process is done shown below RC-mgr
reliance fresh ERP
mini WH/ Data mart DWH independent Data Mart Dependent Data Mart Reliance Fresh(taking one from group directly)
Dependent Data Mart: means the ETL process takes all manager information or dB and keep in the Warehouse. By that the data transmission between warehouse and data mart where depends upon by each other. Here Data mart is also called as ‘Bottom level’/ ‘mini WH’ as shown in blue color in above figure i.e., the data of individual manager (like RF, RC, RP and so on). Hence the data mart depends up on the WH is called dependent data mart.
Independent Data Mart: only one or individual manager i.e., data mart were directly access the ETL process with out any help of Warehouse. That’s why its called independent data mart.
6.1 Two level approaches:
For the both approaches two layers architecture will apply.
1. Top-Bottom level approach, and
2. Bottom- Top level approach.
6.1. Top – Bottom level approach:
The level start from top means as per example Reliance group to their individual managers their ETL process from their to Data Warehouse (top level) and from their to all separate data marts (bottom level).
R Comm. Data Mart
R Power Data Mart
Reliance Group
Warehouse
R Fresh Data Mart
Top level Bottom level
Layer I Layer II
Top – Bottom level approach
In the above the top – bottom level is defined, and this approach is invented by W. H. Inner.
Here, warehouse is top level and all data mart are bottom level as shown in the above figure.
6.2. Bottom – top level approach:
Means from here the ETL process takes directly from data mart (DM) and the data put in the warehouse for reference purpose or storing the DM in the Data WareHouse (DWH).
R comm.
DM
R power
DM DWH
Reliance Group
R fresh DM
Layer I Layer II Bottom level Top level
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