Re: Synchronous replication

On 16/07/10 10:40, Fujii Masao wrote:
> So we should always prevent the standby from applying any WAL in pg_xlog
> unless walreceiver is in progress. That is, if there is no WAL available
> in the archive, the standby ignores pg_xlog and starts walreceiver
> process to request for WAL streaming.

That completely defeats the purpose of storing streamed WAL in pg_xlog 
in the first place. The reason it's written and fsync'd to pg_xlog is 
that if the standby subsequently crashes, you can use the WAL from 
pg_xlog to reapply the WAL up to minRecoveryPoint. Otherwise you can't 
start up the standby anymore.

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