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.
(1999-12-07)
Nearby terms:
SURGE « surjection « surjective « surrogate key
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