Re: Bit count - Mailing list pgsql-novice

From Jasen Betts
Subject Re: Bit count
Date
Msg-id helnbl$ggh$1@reversiblemaps.ath.cx
Whole thread Raw
In response to Bit count  (Nathaniel Trellice <naptrel@yahoo.co.uk>)
List pgsql-novice
On 2009-11-24, Nathaniel Trellice <naptrel@yahoo.co.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
countthe 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
foundat: 

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


pgsql-novice by date:

Previous
From: Rikard Bosnjakovic
Date:
Subject: Re: Merging two GROUP BY-queries
Next
From: Nathaniel Trellice
Date:
Subject: Re: Bit count