Re: Bit count

On 2009-11-24, Nathaniel Trellice <naptrel(at)yahoo(dot)co(dot)uk> wrote:
> 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).

convert it to a text representation of the binary value use regexp_replace to remove the 0s take the length.

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

postgres functions can be written in C (if you have superuser
priviledges) seems like overkill though.