On Wed, 07 Jan 2015 15:25:30 -0500
Dmitri Pal <dpal(a)redhat.com> wrote:
> On 01/07/2015 03:05 PM, Simo Sorce wrote:
> > On Tue, 06 Jan 2015 09:59:08 -0500
> > Dmitri Pal <dpal(a)redhat.com> wrote:
> >> On 01/06/2015 05:54 AM, Jakub Hrozek wrote:
> >>> On Tue, Jan 06, 2015 at 11:31:55AM +0100, Pavel Březina wrote:
> >>>>>> *Users*
> >>>>>> Do we want also to have methods ListDomainUsers() and
> >>>>>> ListUsers() without the name filter?
> >>>>> To list all? What about using '*' for that?
> >>>> We can implement it this way internally, but exposing an easier
> >>>> way to the consumers is nice, imho.
> >>> I'm not too opposed, although I prefer minimal APIs.
> >>>> However, do we actually want to allow to list all users? As
> >>>> Dmitri suggested we may want to require the minimum filter
> >>>> length since the number of users may be very high. The maximum
> >>>> D-Bus message is 128MiB so I think we are good there but I think
> >>>> it can be very time consuming to return all users without some
> >>>> sort of paging.
> >>> This feature is internally dependant on enumerate=true, where we
> >>> already store all standard POSIX attributes (struct passwd, struct
> >>> group) in-memory, do you think the D-Bus "enumeration"
> >>> that much overhead?
> >>> Paging would be really complex, we'd need to store the full
> >>> results in-memory per-client anyway and then pass around some
> >>> kind of cookie to resume iteration..
> >>> In a centralized environment, I wouldn't expect the listing
> >>> commands to be used that commonly. Greeters or login managers
> >>> (gdm) would typically use the cached users instead. Some
> >>> applications (Hi, RHEV-M!) choose to display all their users in
> >>> some kind of table and then I would expect them to implement
> >>> paging themselves:
> >>> for letter in a..z:
> >>> users = ListUsersByNameFilter($letter)
> >>>>>> Do we want some other filter options as well?
> >>>>> In the design I wanted to keep the filtering simple. Unless we
> >>>>> receive some other requirements..
> >>>> Yes, you suggested to allow only asterisk. Implement full regular
> >>>> expression efficiently as Dmitri would be quite problematic since
> >>>> ldb doesn't support regex lookup thus we would have to do this
> >>>> ourselves and therefore we would loose indices, or am I wrong?
> >>> I guess we'd have to grab all the entries and filter them
> >>> ourselves..
> >>> (Yes, this is the reason I chose the asterisk notation in the
> >>> first place) _______________________________________________
> >>> sssd-devel mailing list
> >>> sssd-devel(a)lists.fedorahosted.org
> >>> https://lists.fedorahosted.org/mailman/listinfo/sssd-devel
> >> Several points:
> >> - IMO having a full regular expression support will be an overhead.
> >> - "Begins with" filtering with * to indicate the remaining part
> >> good enough
> > reasonable
> >> - I do not think we should rely on enumeration. I think we should
> >> do a lookup since these operations will be rare.
> > Nope.
> > This is the same thinking the implementers of the nss interface went
> > through. And then users started using enumeration all the time.
> > It may be ok to let users programmatically force full enumeration
> > somehow. But the default should be to return only what is in cache.
> > If you do otherwise people will test applications using * with 3
> > users on the system and then fail spectacularly when there are
> > actually 100K users in the directory.
> I think there is a problem with the approach you suggest.
> Say there is an application that allows you to list groups starting
> with a letter. It is used to define roles for application
> Assume that there is a group "Agroup". It is a new group that does
> not have users yet. But it was created for use with the application
> so that roles can be associated with this group. The admin of the
> application thus wants to start using it.
> This group will never be looked up if "A*" query will be run against
> cache because it will not end up in cache. That would force admin to
> turn full enumeration on SSSD. This is bad.
What matters is the '*' does not do enumeration, if 'ABC*' causes an
online lookup it is fine imo.
Yes, this is exactly what I was proposing. However, handling 'ABC*' on
the back end side must be implemented, currently we only handle a single
entry or enumeration.
I might have confused you because I proposed to first finish the DBus
*responder* work and temporarily require enumeration until we extend the
I hope it makes sense now.