Re: Page layout footprint

Heikki Linnakangas napsal(a):
> Zdenek Kotala wrote:
>> Heikki Linnakangas napsal(a):

<snip>

> AFAICS you can get all the same information from pg_controldata. We have 
> a pretty good idea of the alignments of all the usual platforms anyway. 
> If someone says in a bug report that they're running on x86_64 or 32-bit 
> Sparc, we know what the alignments on those platforms are.
> 
>>> And if you're working at such a low level, it's not that hard to 
>>> calculate the offsets within the struct manually.
>>
>> I'm not sure if it is so easy. Are you able do it for SPARC, PPC or 
>> other non x86 CPUs?
> 
> Not off the top of my head. But I am able to do it on x86 and x86_64 
> which are the platforms I work and debug on.

OK. You convinced me that information could be collected from other sources.

<snip>

>> It could also report changes in alignment.
> 
> Huh? I would be pretty surprised if the alignment changed randomly on 
> some platform.

I thought if somebody change compiler switches - for example 32/64 compilation. 
But it is probably rare case.
Zdenek


-- 
Zdenek Kotala              Sun Microsystems
Prague, Czech Republic     http://sun.com/postgresql