Re: Re[2]: Allowing WAL fsync to be done via O_SYNC

Alfred Perlstein <bright@wintelcom.net>

From: Alfred Perlstein <bright@wintelcom.net>
To: Bruce Momjian <pgman@candle.pha.pa.us>
Cc: Xu Yifeng <jamexu@telekbird.com.cn>, Tom Lane <tgl@sss.pgh.pa.us>, "Mikheev, Vadim" <vmikheev@SECTORBASE.COM>, Peter Eisentraut <peter_e@gmx.net>, pgsql-hackers@postgresql.org
Date: 2001-03-16T15:43:24Z
Lists: pgsql-hackers
* Bruce Momjian <pgman@candle.pha.pa.us> [010316 07:11] wrote:
> > > Could anyone consider fork a syncer process to sync data to disk ?
> > > build a shared sync queue, when a daemon process want to do sync after
> > > write() is called, just put a sync request to the queue. this can release
> > > process from blocked on writing as soon as possible. multipile sync
> > > request for one file can be merged when the request is been inserting to
> > > the queue.
> > 
> > I suggested this about a year ago. :)
> > 
> > The problem is that you need that process to potentially open and close
> > many files over and over.
> > 
> > I still think it's somewhat of a good idea.
> 
> I like the idea too, but people want the transaction to return COMMIT
> only after data has been fsync'ed so I don't see a big win.

This isn't simply handing off the sync to this other process, it requires
an ack from the syncer before returning 'COMMIT'.

-- 
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]