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Siddique Ibrahim, profile picture
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Metadata in data warehouse

Metadata contains answers to questions about the data in a data warehouse. It is stored in a metadata repository and describes pertinent details about the data to users, developers, and the project team. Metadata is necessary for using, building, and administering the data warehouse as it provides information about data extraction, transformations, structure, refreshment, and more. It serves important roles for both business users and IT staff across the data acquisition, storage, and delivery processes.

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Role of Metadata
Why Metadata  Before touches the keyboard by the prominent(superlative) users.  Several questions come to their mind. What are various data in the data warehouse? Is there information about unit sale and costs by product? How old is the data in the warehouse. When was the last time fresh data was brought in? Are there any summaries by month and product?
Why Meta data contd.,  These questions and several more information are very valid and pertinent.  What are answers? Where are the answers? Can ur user see the answers? How easy to get the answers?
What is Meta data?  Metadata in a data warehouse contains the answer to questions about the data in the data warehouse.  Keep the answer in a place called the metadata repository.
Different definitions for metadata  Data about the data.  Table of contents for the data.  Catalog for the data.  Data warehouse roadmap.  Data warehouse directory.  Tongs to handle the data.  The nerve center.
So, what exactly is metadata  It tells u more.  It gives more than the explanation of the semantics and the syntax.  Describes all the pertinent(relevant) aspect of the data in the data warehouse.  Pertinent to whom?  The answer is – primarily to the user and also developer and even project team.
Meta data
Why it is important?  Metadata is necessary for using, building and administering your data warehouse.
For using the data warehouse  Without the metadata support, user cannot get an information every time they needed(user create their own ad hoc report).  Today data warehouses are much larger in size, wide in scope.  User critically need metadata.
For building the data warehouse(extraction team)  Need to know the structure and data content in the data warehouse.  Mapping and data transformations.  Logical structure of data warehouse database.
For administering the data warehouse  Impossible to administer the data warehouse(size)  Large no of questions and queries.  Cannot administer without answers for these questions.  Metadata must address these issues.
List of questions relating to data warehouse
Who needs metadata?  Without metadata, Datawarehouse is like such a filling cabinet without information.  Go through the image column(it address the our question)
Like a nerve center  Metadata placed in a key position and enables communication among various processes.
Why metadata is essential for IT  Development and deployment of data warehouse is joint effort between users and IT staff.  Technical issue-IT primarily responsible design and ongoing administration.  Metadata essential for IT  beginning with the data extraction and ending with information delivery.  It drives and record the each processes.
Summary list of process in which metadata is significant for IT  Data extraction  Data transformation  Data scrubbing  Data staging  Data refreshment  Database design  Query report and design
Automation of DWH tasks
Types by Functional Area  Classify and group in various way-some by usage and who use it  Administrative/End-user/Optimization  Technical/Business  Development/usage  In the data mart/At the workstation  Bank room/front room  Internal/External
Functional Areas  Data Acquisition  Data stroage  Information delivery
Data Acquisition  DWH process related to following functions. Data extraction Data transformation Data cleaning Data integration Data staging
Data aquisition
Data stroage  Data loading  Data archiving  Data management  Use metadata in this area for full data refresh and load.
Information Delivery  Report generating  Query processing  Complex analysis Mostly this are meant for end-user. Metadata recorded in processes of other two areas. It also record OLAP-the developer and administrators are involved in this processes.
Business METADATA  It connect business with DWH.  Business users need more than other users.  Business metadata is like a roadmap.  Tout guide-managers and analysis.
 Must describe the contents in plain language giving information in business teerms.  Example The name of data tables (or) individual element must not be cryptic. The data item name-calc_pr_sle. You need to rename this as calculated-prior- month-sale
Business metadata Contd.,  Much less structured than technical metadata.  Textual documents, spreadsheets, and even business rules and policies not written down completely.
Examples of Business Metadata who Benefits?  Primarily benefits end-users. Managers Business analysis Power users Regular users Casual users Senior managers/ junior managers
Technical Metadata  IT staff- Development and Administration of the data warehouse.  Who Benefits? Project manager Data warehouse administrator Metadata manager Database administrator Business analyst Data quality analyst