Re: LDAP vs. Relational

[mcs@netscape.com (Mark C Smith)]

Luca VEZZADINI wrote:
> 
> Hi all,
> this is very interesting, indeed. And I think I have an extra question to
> raise here, as it relates to this thread.
> 
> LDAP is optimized for read access as write operations are less frequent. But
> does it provide any lock mechanism for concurrent write access? That is a
> very delicate point. Even if we can live without transactions, we must
> guarantee that concurrent write operations don't mess data. If two
> operations have to update an entry at the same time, what happens?

LDAP promises that updates operations are always atomic (i.e., either
they succeed entirely or fail as a set).  If two operations update the
same attribute values in an entry at the same time, one of the updates
will be done first and the other will be done second (and may fail if it
relied on some previous entry state).  Presumably that means a server
will use some kind of internal locking mechanism to ensure that bad
things don't happen to the entry data (structures) and so on.

-- 
Mark Smith
Directory Architect / Netscape Communications Corp.
My words are my own, not my employer's.  Got LDAP?