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Message Posted: Mon, 30 Jan 2006 @ 23:15:48 GMT


     
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Subj:   Primary keys without a Unique Index.
 
From:   Joe Celko

  Is there any DBMS which supports a PK without implementing it as a Unique Index? Would be nice to know how it's done (fast and efficient).  


Look at the compressed bit vectors used by the SAND engine. Another approach that was used in experimental RDBMS projects was via a perfect hashing algorithm (a perfect hash has no clashes, so when you get one, you know that the key has been used).



     
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