As others have said, you need proof.

I can hazard a guess as to the origins of this myth.

Sometimes the natural key to a table is composite, that is
1+ columns make of the primary key.

In that case, a number single column key will likely prove
faster, simply because there are fewer comparisons to make.

Though I don't know how much faster that might be.  It may
be too small to measure without a large result set to test.

As an aside, Oracle recommends using SYS_GUID to generate
primary keys. Try this and see what data type you get:

 SQL>  select sys_guid() from dual;

Try using the dump() function, and look up the datatype code in
the datatypes section of the SQL manual.

Or just look at the docs for SYS_GUID.

Jared





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Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist