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Metadata

Metadata at the most basic level is simply defined as “data about data”. An item of metadata describes the specific characteristics about an individual data item. In the database realm, metadata is defined as, “data about data, through which the end-user data are integrated and managed.” (Rob & Coronel, 2009)  Metadata in a database typically store the relationships that link up numerous pieces of data.  “Metadata names these fields, describes the size of the fields, and may put restrictions on what can go in the field (for example, numbers only).” (Sheldon, 2001).


“Therefore, metadata is information about how data is extracted, and how it may be transformed. It is also about indexing and creating pointers into data. Database design is all about defining metadata schemas.” (Sheldon, 2001)  Meta data can be stored either internally, in the same file as the data, or externally, in a separate area.  If the data is stored internally, the metadata is together with the data, making it more easily accessible to view or change. However, this method creates high redundancy. If metadata is stored externally, the searches can become more efficient. There is no redundancy but getting to this metadata may be a little more technical.


All the metadata is stored in a data dictionary or a system catalog. The data dictionary is most typically an external document that is created in a spreadsheet type of document that stores the conceptual design ideas for the database schema.  The data dictionary also contains the general format that the data, and in effect the metadata, should be.  Metadata is an essential aspect to database design, it allows for increased processing power, due to the fact that it can help create pointers and indexes. 
Database schema





This image is an example of a database schema that includes the metadata type that it is as well as the information it is, including the size of information it can hold.





Works Cited Edit

Rob, P., & Coronel, C. (2009). Database Systems Design, Implementation, And Management. Boston: Course Technology.

Sheldon, T. (2001). Metadata. Retrieved 12 03, 2009, from Linktionary: http://www.linktionary.com/m/metadata.html

 

Pages in category "UPDATE to Metadata"

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