Re: XQuery (and XML) vs LISP

Gene Wirchenko wrote:
[...]
  I am having
> trouble at work trying to work out how to implement a multi-user
> database application with predicate locking. I have never seen
> anything on how to implement it.

You might want to reconsider your design for at least two reasons:

1. In general. predicate locking conflict detection is an NP-hard problem as has been known since 1976 (R System) so you may not want to go this way.
2. A reasonable subset of predicate locking, known as "the next key locking" has already been implemented in major databases such as DB2 and SQL Sever (see Mohan's ARIES protocol, 1981) so your database might already have it. Even MySQL (InnoDB) has it.

In any case, there is a vast body of literature on predicate locking that shoud be satisfactory at any level of familiarity with the subject.

>
> Sincerely,
>
> Gene Wirchenko
Received on Tue Feb 21 2006 - 21:29:27 CET