[Date Prev][Date Next]
[Chronological]
[Thread]
[Top]
RE: 2.1.17 performance issues
Today at 9:15am, John Madden wrote:
> > Not only is it dangerous, but since it is UNDOCUMENTED which DB_CONFIG
> > statements override slapd configuration options, it is bound to happen
> > that someone is going to use checkpoint in their slapd.conf file and
> > also have it in their DB_CONFIG file. The dbnosync option is going to
> > cause a similar problem. It will be commented out in either slapd.conf
> > or DB_CONFIG but not both and someone is going to think it's off when
> > they don't remember to check both places and get a rude surprise.
>
> No Berkeley config options "override" slapd config options. BDB is a
> completely separate entity -- imagine you were using back-sql -- you
> wouldn't expect slapd to have anything to do with your SQL backend, would
> you?
>
> Given this paradigm, I imagine that dbnosync has no effect on filesystem
> syncing with back-bdb unless BDB has hooks to allow client applications to
> request an fsync. ...Others can confirm that one.
I'm sorry John, but you're just plain wrong. Setting dbnosync in the
slapd.conf file causes back-bdb to invoke the DB_ENV->set_flags()
routine to disable syncing after every transaction. If you don't set it
in the slapd.conf file (or have it commented out), but have "set_flags
DB_TXN_NOSYNC" in your DB_CONFIG file, you have turned off syncing.
>From the DB_ENV->set_flags page:
"Because the DB_CONFIG file is read when the database environment is
opened, it will silently overrule configuration done before that time."
--
Frank Swasey | http://www.uvm.edu/~fcs
Systems Programmer | Always remember: You are UNIQUE,
University of Vermont | just like everyone else.
=== God Bless Us All ===