Re: Review: Patch to compute Max LSN of Data Pages

On Wed, Nov 28, 2012 at 3:06 AM, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>wrote:

> Amit Kapila escribió:
> >
> > Friday, November 23, 2012 5:38 AM Muhammad Usama wrote:
>
> > >- I think when finding the max LSN of single file the utility should
> > > consider all relation segments.
> > Would you like to find for all relation related segments:
> > Like 12345, 12345.1 ... 12345.n Or
> > 12345, 12345.1 ... and 12345_vm, 12345.1_vm
> >
> > But how about if user asks for 12345.4, do we need to find all greater
> > than 12345.4?
> >
> > IMHO, as this utility is not aware of relation or any other logical
> > entity and deals with only file or directory, it is okay to find
> > only for that file.
>
> Hmm. I think I'd expect that if I give pg_computemaxlsn a number, it
> should consider that it is a relfilenode, and so it should get a list of
> all segments for all forks of it. So if I give "12345" it should get
> 12345, 12345.1 and so on, and also 12345_vm 12345_vm.1 and so on.
> However, if what I give it is a path, i.e. it contains a slash, I think
> it should only consider the specific file mentioned. In that light, I'm
> not sure that command line options chosen are the best set.
>
> +1

>
> --
> Álvaro Herrera http://www.2ndQuadrant.com/
> PostgreSQL Development, 24x7 Support, Training & Services
>