Re: Another idea for dealing with cmin/cmax - Mailing list pgsql-hackers

Martijn van Oosterhout wrote:
> On Fri, Sep 29, 2006 at 09:35:31AM +0100, Heikki Linnakangas wrote:
>> We could get rid of t_hoff, because we should always be able to
>> calculate the header size. Then we're down to 18 bytes.
>
> Without t_hoff, how do you know the size of the null bitmap? You could
> probably do it only if you assume the null bitmap, if present, always
> covers all the columns...

I think we assume that already. heap_form_tuple reserves space for the 
bitmap like this:
   if (hasnull)       len += BITMAPLEN(numberOfAttributes);

-- 
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com