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Bit count

From: Nathaniel Trellice <naptrel(at)yahoo(dot)co(dot)uk>
To: pgsql-novice(at)postgresql(dot)org
Subject: Bit count
Date: 2009-11-24 15:47:05
Message-ID: 998131.26971.qm@web25007.mail.ukl.yahoo.com (view raw or flat)
Thread:
Lists: pgsql-novice
I'd like to use an integer column (16 bits will suffice) to hold a bit-field. I'd like to be able to efficiently count the number of bits set in this field.

Is there a built-in function call I can use? (I can't find one in the manual).

If not, can anyone recommend the most efficient way within postgres to implement the kind of bit-counting tricks found at:

http://gurmeetsingh.wordpress.com/2008/08/05/fast-bit-counting-routines/
http://graphics.stanford.edu/~seander/bithacks.html

Nathaniel



      

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