From: | Jasen Betts <jasen(at)xnet(dot)co(dot)nz> |
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To: | pgsql-novice(at)postgresql(dot)org |
Subject: | Re: Bit count |
Date: | 2009-11-26 11:04:21 |
Message-ID: | helnbl$ggh$1@reversiblemaps.ath.cx |
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Lists: | pgsql-novice |
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.
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