RE: RE: [COMMITTERS] pgsql/src/backend/access/transam ( xact.c xlog.c)

> > > > New CHECKPOINT command.
> > > > Auto removing of offline log files and creating new file
> > > > at checkpoint time.
>
> Can you tell me how to use CHECKPOINT please?

You shouldn't normally use it - postmaster will start backend
each 3-5 minutes to do this automatically.

> > > Is this the same as a SAVEPOINT?
> >
> > No. Checkpoints are to speedup after crash recovery and
> > to remove/archive log files. With WAL server doesn't write
> > any datafiles on commit, only commit record goes to log
> > (and log fsync-ed). Dirty buffers remains in memory long
>
> Is log fsynced even I turn of -F?

Yes, though we can change this. We also can implement now
feature that Bruce wanted so long and so much -:) -
fsync log not on each commit but each ~ 5sec, if
losing some recent commits is acceptable.

Nevertheless, when bufmgr replaces dirty buffer it must
ensure first that log record of last buffer update is
on disk already and so bufmgr forces log fsync if required.
This cannot be changed - rule is simple: log before applying
changes to permanent storage.

Vadim