Re: Parallel pg_dump for 9.1

On 3/29/10 7:46 AM, Joachim Wieland wrote:
> I actually assume that whenever people are interested
> in a very fast dump, it is because they are doing some maintenance
> task (like migrating to a different server) that involves pg_dump. In
> these cases, they would stop their system anyway.

Actually, I'd say that there's a broad set of cases of people who want
to do a parallel pg_dump while their system is active. Parallel pg_dump
on a stopped system will help some people (for migration, particularly)
but parallel pg_dump with snapshot cloning will help a lot more people.

For example, imagine a user who has a 16-core machine on a 14-drive RAID
10, and a 100-table 1TB database. At 2am, this person might reasonaly
want to allocate a large portion of the machine resources to the dump by
giving it 4 threads, without cutting access to the application.

So: if parallel dump in single-user mode is what you can get done, then
do it. We can always improve it later, and we have to start somewhere.
But we will eventually need parallel pg_dump on active systems, and
that should remain on the TODO list.

--
-- Josh Berkus
PostgreSQL Experts Inc.
http://www.pgexperts.com