Rick,
I use surrogate keys when the obvious primary key value has the possibility
of being updated by the application.
For example, you would think that a Social Security number might be a
candidate for use as a primary key in a college database. What we found
upon study is that, the Soc Sec # provided at college application time is
sometimes the parents number, rather than the student's number. So, it
changes about 10% of the time.
Of course, the cons of primary keys are that you probably will need an
additional index on the table to allow lookup by a secondary value. In the
above case, the primary key was a surrogate value supported by a sequence,
with a secondary index on the soc-sec column. The cost of using the
surrogate primary key was the additional index.
My current database that I am designing is only using surrogate keys. It
provides a level of comfort in that we don't ever have to worry about the
primary key being changed - it never will.
hope this helps.
Tom Mercadante
Oracle Certified Professional
-----Original Message-----
Sent: Tuesday, June 12, 2001 9:00 AM
To: Multiple recipients of list ORACLE-L
Hi All,
Can someone explain pros/cons to using surrogate keys(i.e.,sequences) vs
non-surrogate keys?
Thanks
Rick
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