Difference between DM / DW / ODS? 1

[RPa]

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Sometimes the question pops up what the difference is between a Datawarehouse (DW), a datamart (DM), and a Operational DataStore (ODS). The difference between a DM and a DW is quite clear reading Inmon's classic &quot;Building the Data Warehouse&quot;, and other articles, but what is an ODS in this context?

 

[yaffle]

An ODS sits conceptually somewhere between a simple copy of an OLTP database for reporting purposes, and a full data warehouse (or atomic data store).<br>
Data warehouses and data marts consist of information that is summarised and reformatted to provide decision support at the enterprise and departmental levels. They do not address operational data access needs.<br>
Operational data stores are populated with information from operational systems and external data. The data typically remains close to its operational form rather than being transformed and enhanced, as it is for data warehouses and data marts. It is reorganised to provide detailed data efficiently, in the form most likely to be needed by operational staff for their reporting.<br>
Since there's less transformation involved, an ODS is typically updated frequently, possibly in real time alongside transactions performed in the OLTP systems.

 

[thomca01]

(Data Mart)<br>
A subset of a data warehouse that focuses on one or more specific subject areas. The data is usually extracted from the data warehouse and further denormalized and indexed to support intense usage by targeted customers.<br>
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(Data Warehouse)<br>
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An implementation of an informational database used to store sharable data sourced from an operational database of record. It is typically a subject database that allows users to tap into a company’s vast store of operational data to track and respond to business trends and facilitate forecasting and planning efforts. It is a collection of integrated, subject-oriented databases designed to support the DSS function, where each unit of data is relevant to some moment in time. The data warehouse contains atomic data and lightly summarized data.<br>
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ODS<br>
An ODS is an intergrated database of operational data. Its sources include legacy systems and it contains current or near-term data. An ODS may contain 30 to 60 days of information, while a data warehouse typically contains years of data.<br>
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Hope this help clear things up for you.<br>
<br>

 

[jarh]

Here there are the differences:

In a general way ODS is the DB that contains data from the OLTP systems but that data is used to support the tactical decision making process.

DW(Data Warehouse) is the summary of ODS data that is used to support eh strategic decision making process.(croporate info)

DM(Data Mart) DM is a subset of DW specifically for example per each department of the company in order to obtain specific strategical information over the business

I think it makes sense right?

 

[Guest_imported]

Why do you say that a DW has summary level data? Why not detailed data in the DW? What if an executive wants to drill through the summary data to the granular details?

 

[Endeca]

An Operational Data Store is time sensitive data. Typically a data warehouse stores historical data. The ODS takes customer touchpoint data and stores that day's information. Then at a predetermined time, loads to the data warehouse and starts over again. It's use is for current information without going against a company's transactional systems (order processing, etc.)