LDB_SCOPE_ONELEVEL without full traversal?

[Volker Lendecke]

On Thu, Dec 07, 2006 at 08:58:36AM +1100, tridge at samba.org wrote:
>  > The problem is: are one level searches really rare?
> 
> I can't think of any examples that would matter. If you say they
> aren't rare, then you'll have to come up with at least one example :-)

If I was to put the registry into ldb, then I would expect
EnumValue calls to be frequent. I don't have hard numbers,
but one reason to put smb share definitions into the
registry was to make the 10.000-share server possible. Make
that 3 custom smb.conf settings per share, and you end up
pretty quickly with a number of registry values that
preclude a full tdb dump on every tconX.

>  > Human speed may be slow, but humans comply more then machines when they
>  > have to wait too much ;-)
> 
> yes, but ldb can do a full scan on a AD directory for a company with
> 10s of thousands of users in a about a second or so on my laptop. 
> 
> So our full scans are often faster than a normal ldap server does
> indexed scans :-)

Sorry, but I have to disagree here. I had to optimize
winbind with about 30.000 entries in winbindd_idmap.tdb. It
spent a good share of CPU walking the degenerated tdb hash
chains. This was partly due to the users being in quite many
groups, and winbind had to do sid2gid calls on all groups.
This on a server where 17.000 users did session setups
within 60 minutes. Not fake, this is a real world server.

> If ldb was being used for _really_ big databases (10s of millions of
> records) then I'd agree. I'm just happy to leave that part of the
> problem to the real ldap databases, and rely on the fact that we can
> backend to a real ldap server.

It's not the huge databases, it's that *many* calls to the
non-indexed search might be necessary.

> My attitude to this might change, but right now I would like ldb to
> conquer the "small, fast, light" space before it starts trying to get
> into the complexity of big databases.

I just doubt scanning a big tdb on every tconX is a good
idea, but that's just me. Traversing a tdb has just hurt us
too many times.

Volker
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