[HACKERS] Will switchover still need a checkpoint in 9.1 SR Hot Standby
In 9.0 (as in earlier versions) a former standby host has to do a full checkpoint before becoming available as an independent database instance in either switchover or failover scenarios. For most combinations of of bigger than minimal shared buffers and non-memory-speed disks this can take from several seconds to tens of minutes on busy systems. Is the pre-activation checkpoint still required in 9.1 ? The reason I ask is that I'm looking into making planned switchovers and adding partitions more instantaneous. Streaming replication provides replica lag of only millisecond vs. high tens or even hundreds of milliseconds achievable on trigger-based replication systems like Londiste. Where Londiste currently wins, is the ability to become available instantaneously without any checkpoint or other lengthy maintenance operations. -- --- Hannu Krosing PostgreSQL Infinite Scalability and Performance Consultant PG Admin Book: http://www.2ndQuadrant.com/books/ -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Will switchover still need a checkpoint in 9.1 SR Hot Standby
On Sun, Aug 7, 2011 at 8:57 AM, Hannu Krosing ha...@2ndquadrant.com wrote: In 9.0 (as in earlier versions) a former standby host has to do a full checkpoint before becoming available as an independent database instance in either switchover or failover scenarios. For most combinations of of bigger than minimal shared buffers and non-memory-speed disks this can take from several seconds to tens of minutes on busy systems. For switchover, you issue a checkpoint first, to reduce this time as much as possible. Is the pre-activation checkpoint still required in 9.1 ? Yes, but I've found a way to remove them in 9.2 and will be patching that soon. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Will switchover still need a checkpoint in 9.1 SR Hot Standby
On Aug 7, 2011, at 11:01 AM, Simon Riggs wrote: On Sun, Aug 7, 2011 at 8:57 AM, Hannu Krosing ha...@2ndquadrant.com wrote: In 9.0 (as in earlier versions) a former standby host has to do a full checkpoint before becoming available as an independent database instance in either switchover or failover scenarios. For most combinations of of bigger than minimal shared buffers and non-memory-speed disks this can take from several seconds to tens of minutes on busy systems. For switchover, you issue a checkpoint first, to reduce this time as much as possible. Is the pre-activation checkpoint still required in 9.1 ? Yes, but I've found a way to remove them in 9.2 and will be patching that soon. hi simon, this is highly interesting. this is am important issue for big iron. can you share the idea you have in mind? many thanks, hans -- Cybertec Schönig Schönig GmbH Gröhrmühlgasse 26 A-2700 Wiener Neustadt, Austria Web: http://www.postgresql-support.de -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
