Re: Allowing multiple concurrent base backups

On Wed, Jan 12, 2011 at 10:24:31AM -0500, Tom Lane wrote:
> Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> writes:
> > On 12.01.2011 17:15, David Fetter wrote:
> >> On Wed, Jan 12, 2011 at 10:26:05AM +0100, marcin mank wrote:
> >>> Considering that parallell base backups would be io-bound (or
> >>> network-bound), there is little need to actually run them in
> >>> parallell
> >> 
> >> That's not actually true.  Backups at the moment are CPU-bound,
> >> and running them in parallel is one way to make them closer to
> >> I/O-bound, which is what they *should* be.
> 
> > That's a different kind of "parallel". We're talking about taking
> > multiple backups in parallel, each using one process, and you're
> > talking about taking one backup using multiple parallel processes
> > or threads.
> 
> Even more to the point, you're confusing pg_dump with a base backup.
> The reason pg_dump eats a lot of CPU is primarily COPY's data
> conversion and formatting requirements, none of which will happen in
> a base backup (streaming or otherwise).

Oops.  That'll teach me to post before coffee. :P

Cheers,
David.
-- 
David Fetter <david@fetter.org> http://fetter.org/
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