Обсуждение: Opening a recovering DB in for read-only access?
Sounds somewhat evil, I know, but I was wondering if it was even remotely possible with the current design? The reason: we are contemplating using pg_standy to create a warm-standby. It would be a bonus if we would run read-only queries against this DB to take some of the load off or production servers. We currently use slony to provide warm-standby *and* read-only access, but pg_standby is a great deal more appealing...especially if there was some way to do read-only access at the same time. FWIW, the data would not even need to be completely consistent ... the kinds of things we are looking at offloading are large summary-type sequential scans of big tables. -- ---------------------------------------------------------------- Philip Warner | __---_____ Albatross Consulting Pty. Ltd. |----/ - \ (A.B.N. 75 008 659 498) | /(@) ______---_ Tel: (+61) 03 5330 3171 | _________ \ Fax: (+61) 03 5330 3172 | ___________ | http://www.rhyme.com.au <http://www.rhyme.com.au/> | / \| | --________-- GPG key available upon request. | / |/
On Thu, Nov 20, 2008 at 21:45, Philip Warner <pjw@rhyme.com.au> wrote: > > Sounds somewhat evil, I know, but I was wondering if it was even > remotely possible with the current design? > > The reason: we are contemplating using pg_standy to create a > warm-standby. It would be a bonus if we would run read-only queries > against this DB to take some of the load off or production servers. > > We currently use slony to provide warm-standby *and* read-only access, > but pg_standby is a great deal more appealing...especially if there was > some way to do read-only access at the same time. > > FWIW, the data would not even need to be completely consistent ... the > kinds of things we are looking at offloading are large summary-type > sequential scans of big tables. Uhh sounds like you are describing hot standby (currently in the works for 8.4) see: http://wiki.postgresql.org/wiki/Hot_Standby http://archives.postgresql.org/pgsql-hackers/2008-11/msg00005.php Synchronous replication might also be of interest http://archives.postgresql.org/pgsql-hackers/2008-11/msg00987.php
Alex Hunsaker wrote > > Uhh sounds like you are describing hot standby (currently in the works > for 8.4) see: > Yep. That's exactly what I'm talking about. Thanks for the links!
On Fri, 2008-11-21 at 15:45 +1100, Philip Warner wrote: > Sounds somewhat evil, I know, but I was wondering if it was even > remotely possible with the current design? > > The reason: we are contemplating using pg_standy to create a > warm-standby. It would be a bonus if we would run read-only queries > against this DB to take some of the load off or production servers. > > We currently use slony to provide warm-standby *and* read-only access, > but pg_standby is a great deal more appealing...especially if there was > some way to do read-only access at the same time. Yes, exactly what I'm working on now, currently patch in review. > FWIW, the data would not even need to be completely consistent ... the > kinds of things we are looking at offloading are large summary-type > sequential scans of big tables. Access to inconsistent data has not been agreed. We will only allow access to consistent data with this approach. -- Simon Riggs www.2ndQuadrant.comPostgreSQL Training, Services and Support