Re: Page layout footprint

Zdenek Kotala wrote:
> The original proposal 
> (http://archives.postgresql.org/message-id/489FC8E1.9090307@sun.com)
> contains two parts. First part is implementation of --footprint cmd line 
> switch which shows you  page layout structures footprint. It is useful 
> for development (mostly for in-place upgrade) and also for manual data 
> recovery when you need to know exact structures.

I'm afraid I still fail to see the usefulness of this. gdb knows how to 
deal with structs, and for manual data recovery you need so much more 
than the page header structure. And if you're working at such a low 
level, it's not that hard to calculate the offsets within the struct 
manually.

BTW, this makes me wonder if it would be possible to use the 
upgrade-in-place machinery to convert a data directory from one 
architecture to another? Just a thought..

> However, there is still --footprint switch which is useful and it is 
> reason why I put it on wiki for review and feedback. The switch could 
> also use in build farm for collecting footprints from build farm members.

If we needed more information about the architectures, we could just 
collect the output of pg_controldata. But I think the configure logs 
already contains all the useful information.

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