[Bucardo-general] fsm and vm files generated under $PGDATA/base

Rosser Schwarz rosser.schwarz at gmail.com
Tue Mar 2 21:18:05 UTC 2010

On Tue, Mar 2, 2010 at 1:56 PM, akp geek <akpgeek at gmail.com> wrote:
>              During the replication process , files are getting generated in
> $PGDATA/base directory. Some of the file end up with _fsm and some _vm.

The *_fsm files are used for a relation's Free Space Map, which tracks
... free space in the relation (tuples/pages which are known dead and
re-usable).  The *_vm files store the Visibility Map, which is a list
of pages containing only tuples visible to all transactions.  They're
generated and used by Postgres' autovacuum daemon.  Like the *.1, *.2
... *.N files that Postgres creates to partition tables' disk files at
one gbyte boundaries, you'll want to leave them alone.

See sections 53.3 and 53.4 of TFM for 8.4 for further details.



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