Re: Chronic performance issue with Replication Failover and FSM.

On 14.03.2012 01:53, Josh Berkus wrote:
> 1. The Free Space Map is not replicated between servers.
>
> 2. Thus, when we fail over to a replica, it starts with a blank FSM.

The FSM is included in the base backup, and it is updated when VACUUM 
records are replayed.

It is also updated when insert/update/delete records are replayed, 
athough there's some fuzziness there: records with full page images 
don't update the FSM, and the FSM is only updated when the page has less 
than 20% of free space left. But that would cause an error in the other 
direction, with the FSM claiming that some pages have more free space 
than they do in reality.

--   Heikki Linnakangas  EnterpriseDB   http://www.enterprisedb.com