Re: Lock-free databases

Christopher Browne wrote:
> > "Joe Seigh" <jseigh_01_at_xemaps.com> wrote in message
[...]
> >> I'm talking about real lock-free, e.g. making the indices lock-free
> >> to allow concurrent updates without having to rebuild the indices,
> >> or allowing queries to run concurrently with updates.
> >
> > You may be interested to know that Oracle (or Rdb or Postgres or
> > Interbase) do just that, "allow queries to run concurrently with
> > updates".
>
> But they do _not_ do this via entirely eliminating locking. They all
> have extensive infrastructure for lock management.

So what ? I was responding to this specific piece: "allow queries to run concurrently with
 updates". That's exactly what the DBs I've mentioned do and they achieve it without locking.

>
> It's well and good that they try to avoid the problems associated with
> heavy-handed locking policies, but it is NOT at all the case that they
> are "lock-free."

Right. However, if you read the book I mentioned earlier, you'll discover that there are concurrency control techniques that do not require locking e.g. MVTSO (multiversion with timestamp ordering). Received on Fri Nov 04 2005 - 19:56:20 CET