
> > committed". The problem is when a client is told something, 
> > that is not true after a crash, which can happen if the second
> > flush is left out.
> 
> But commercial db's do that.  They return 'done' for every query, while
> they write they log files ever X seconds.  We need to allow this.  No
> reason to be more reliable than commercial db's by default.  Or, at
> least we need to give them the option because the speed advantage is
> huge.
> 
I agree, but commercial db's don't do that. 
Oracle does not (only on Linux).
Informix only does it when you specially create the database
(create database dada with buffered log;) I always use it :-)
Informix has a log buffer, which is flushed at transaction commit
(unbuffered logging) or when the buffer is full (buffered logging).
None of them do any "every X seconds stuff".

Andreas

Fri, 25 Jun 1999 16:10:19 +0200
Zeugswetter Andreas IZ5 <Andreas.Zeugswetter@telecom.at>
AW: [HACKERS] fsynch of pg_log write..
> 
> > > committed". The problem is when a client is told something, 
> > > that is not true after a crash, which can happen if the second
> > > flush is left out.
> > 
> > But commercial db's do that.  They return 'done' for every query, while
> > they write they log files ever X seconds.  We need to allow this.  No
> > reason to be more reliable than commercial db's by default.  Or, at
> > least we need to give them the option because the speed advantage is
> > huge.
> > 
> I agree, but commercial db's don't do that. 
> Oracle does not (only on Linux).
> Informix only does it when you specially create the database
> (create database dada with buffered log;) I always use it :-)
> Informix has a log buffer, which is flushed at transaction commit
> (unbuffered logging) or when the buffer is full (buffered logging).
> None of them do any "every X seconds stuff".

Yes!  All my clients use Informix buffered logging.  Now, these are law
firms running their billing systems using Informix.  The 'buffer full'
write is kind of limited in that it does not give a good time limit on
vulnerability.  It has to do this because it wants to write a full tape
block.  Newer versions worked around this with some kind of intermediate
fix(not sure).  Anyway, having a time limit in the fsync will give us
goo performance with a reliable/limited exposure to risk.

-- 
  Bruce Momjian                        |  http://www.op.net/~candle
  maillist@candle.pha.pa.us            |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

Fri, 25 Jun 1999 11:37:03 -0400 (EDT)
Bruce Momjian <maillist@candle.pha.pa.us>
Re: AW: [HACKERS] fsynch of pg_log write..