surrogate key


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surrogate key

(database)
A unique primary key generated by the RDBMS that is not derived from any data in the database and whose only significance is to act as the primary key.

A surrogate key is frequently a sequential number (e.g. a Sybase "identity column") but doesn't have to be. Having the key independent of all other columns insulates the database relationships from changes in data values or database design and guarantees uniqueness.

Some database designers use surrogate keys religiously regardless of the suitability of other candidate keys. However, if a good key already exists, the addition of a surrogate key will merely slow down access, particularly if it is indexed.

Compare: intelligent key.
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surrogate key debate; however, it is important to know that although surrogate keys may uniquely identify the record, they do not always uniquely identify the data.
A key is some unique combination of a thing's existing properties, whilst a surrogate key is a new property assigned as the thing enters the database, solely for the purpose of identifying it and for no other purpose.
The initial data sets created off the acute care data may derive the surrogate key for an encounter record from a combination of patient account number and discharge date.
However, with one or more of the dimensions degenerated, it is not likely that a surrogate key was created that represents the items within the degenerated dimensions.
For those who haven't heard the term, here is my attempt at a quick summary: A surrogate key is a generated unique value that is used as the primary key of a database table; database designers tend to consider surrogate keys when the natural key consists of many columns, is very long, or may need to change.
announces UBS AG, a leading global financial services firm, has deployed Sapior Redbridge, Sapior's specialised surrogate key mapping tool, to speed indexing and join performances of its credit risk data warehouse.
today unveiled Redbridge(tm), a specialised surrogate key mapping tool for high performance data integration.
These critical features--along with surrogate key lookup and automatic parallelism--ensure greater ease of use in importing, exporting and sharing jobs and functions among users in disparate computing environments.
As this implies a large scale implementation, surrogate keys are used to ensure the data warehouse expansion over time.
Automated development of standard BI logic: incremental data loads, slowly changing dimensions, surrogate keys, de-normalization.
Standardization should include information which addresses when and how natural keys or surrogate keys are used.
Prima's other requirements were that the selected product be purely Microsoft-centric and able to take advantage of all SQL Server(TM) capabilities, such as the use of foreign key constraints and surrogate keys.