Re: Index Page Split logging

On Jan 2, 2008 6:24 PM, Martijn van Oosterhout <kleptog(at)svana(dot)org> wrote:

> On Wed, Jan 02, 2008 at 04:46:11PM +0530, Gokulakannan Somasundaram wrote:
> > > All indexes are done by user-defined functions, even b-trees. People
> can
> > > make their own b-tree indexes by defining an operator class. Note that
> > > "user-defined" is this case means anything called via the fmgr
> > > interface.
> >
> > Again, i think i have one more wrong understanding. My understanding is,
> > We are discussing about user-defined functions because, they might be
> > actually be mutable functions, but the user might have classified as
> > immutable.
>
> This is where it gets a bit beyond by depth, so someone may have to
> correct me. The point is that during the recovery the system is not yet
> fully running and not everything works yet. For example, what happens
> if the system crashed halfway through updating a page in pg_proc and
> that page needs to be recovered from WAL. Yet to insert into the index
> you need to be able to read pg_am, pg_amproc, pg_proc at least,
> probably more.
>
> The point being, you can't rely on anything except WAL during recovery.
>
> Thanks a lot for the nice explanation. That was something new for
me....:((

--
Thanks,
Gokul.