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

> > Earlier, Vadim was talking about arranging to share fsyncs of the WAL
> > log file across transactions (after writing your commit record to the
> > log, sleep a few milliseconds to see if anyone else fsyncs before you
> > do; if not, issue the fsync yourself).  That would offer less-than-
> > one-fsync-per-transaction performance without giving up any 
> > guarantees.
> > If people feel a compulsion to have a tunable parameter, let 'em tune
> > the length of the pre-fsync sleep ...
> 
> Already implemented (without ability to tune this parameter - 
> xact.c:CommitDelay, - yet). Currently CommitDelay is 5, so
> backend sleeps 1/200 sec before checking/forcing log fsync.

Should definitely make that tuneable (per installation is imho sufficient), 
no use in waiting if the dba knows there is only very little concurrency. 
IIRC DB/2 defaults to not using this "commit pooling".

Andreas