Bruce Momjian wrote:
>
> >
> > > For instance, if there are assumptions that all data blocks are
> > > written before this fact is recorded in a log file, then
> > > "write data blocks" "fsynch" "write log" "fsynch" doesn't break
> > > that assumption,
> > >
> > Are we really doing a sync after the pg_log write ? While the sync
> > after datablock write seems necessary to guarantee consistency,
> > the sync after log write is actually not necessary to guarantee consistency.
> > Would it be a first step, to special case the writing to pg_log, as
> > to not sync (extra switch to backend) ? This would avoid the syncs
> > for read only transactions, since they don't cause data block writes.
>
> You are right. We don't need a sync after the pg_log write.
We need. I agreed with extra switch to backend.
Vadim
