Re: Forcing WAL flush

> Le 2013-01-07 à 16:49, james a écrit :
>
>> Is there a way to force a WAL flush so that async commits (from other connections) are flushed, short of actually updating a sacrificial row?
>>
>> Would be nice to do it without generating anything extra, even if it is something that causes IO in the checkpoint.
>>
>> Am I right to think that an empty transaction won't do it, and nor will a transaction that is just a NOTIFY?
>
> Does pg_start_backup() trigger a full WAL flush?
>
> http://www.postgresql.org/docs/9.2/static/continuous-archiving.html#BACKUP-LOWLEVEL-BASE-BACKUP
> http://www.postgresql.org/docs/9.2/static/functions-admin.html#FUNCTIONS-ADMIN-BACKUP-TABLE
>
> Bye,
> François

That sounds rather heavyweight!

I'm looking for something lightweight - I might call this rather often,
as a sort of application-level group commit where I commit async but
defer the ack to the requester (or other externally visible side
effects) slightly until some other thread forces a flush.