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
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