Re: [HACKERS] Hot Backup Ability

On Tue, 29 Jun 1999, Bruce Momjian wrote:

> > Just out of curiosity, I did a DUMP on the database while running a script
> > that ran a pile of updates. When I restored the database files, it was so
> > corrupted that I couldn't even run a select. vacuum just core dumped...
>
> When you say DUMP, you mean pg_dump, right? Are you using 6.5?

Erm. Well, no. I was running ufsdump. Once I read the section on mvcc and
re-did the test with the pg_dump, I realised that it does work as
documented...

I should think this is a good feature to broadcast to everyone. I don't
think other free systems support it.

The thing I got confuzed with that blocked transactions was the pg_vacuum.
Seeing as how it physically re-arranges data inside the tables and
indexes, is there any hope for not blocking the table for a long time as
it re-arranges a 15 gig table?

Will re-usable page support (whenever it is expected) eliminate the need
for vacuum?

Would it be easy to come up with a scheme for the vacuum function defrag a
set number of pages and such, release its locks if there is another
process blocked and waiting, then resume after that process is finished?

-Michael