Обсуждение: RE: [HACKERS] 6.6 items

What about potential deadlocking issues with vacuum?  Haven't tried to
deadlock vacuum, but wondering if it's possible.-DEJ

> -----Original Message-----
> From:    Bruce Momjian [SMTP:maillist@candle.pha.pa.us]
> Sent:    Tuesday, June 08, 1999 11:41 AM
> To:    Thomas Lockhart
> Cc:    Vadim Mikheev; Don Baccus; ZEUGSWETTER Andreas IZ5;
> pgsql-hackers@postgreSQL.org; 'kar@webline.dk'
> Subject:    Re: [HACKERS] 6.6 items
> 
> > > Or you talk that this should be mentioned in 
> > > announcement/release notes?
> > 
> > I've added a mention of this in the release notes, and (Bruce) since
> > I'll be regenerating INSTALL and HISTORY it will be included in those.
> > I *should* be able to retrofit it into admin.ps.gz also...
> 
> Added to release notes:
> 
>         Another big benefit of MVCC is that
> <application>pg_dump</application>
>         can now generate consistent backups of live, active databases,
> without
>         blocking active transactions.
> 
> Good idea to add this.  I also added to the Enhancements list:
> 
> pg_dump now can generate consistent snapshots on active databases(Vadim) 
> 
> -- 
>   Bruce Momjian                        |  http://www.op.net/~candle
>   maillist@candle.pha.pa.us            |  (610) 853-3000
>   +  If your life is a hard drive,     |  830 Blythe Avenue
>   +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

"Jackson, DeJuan" wrote:
> 
> What about potential deadlocking issues with vacuum?  Haven't tried to
> deadlock vacuum, but wondering if it's possible.

Shouldn't be possible.

Vacuum never acquires AccessExclusive lock on more than
one table at once. This lock is released immediately
after a relation processed.

SELECT/COPY_TO queries from pg_dump lock relations
in AccessShare mode for duration of query.

Vadim