First writings on DsGetNCChanges call

[tridge at samba.org]

Hi Anatoliy,

 > I uploaded the work-in-progress branch here: http://repo.or.cz/w/Samba/aatanasov.git?a=shortlog;h=refs/heads/samba_drsuapi

thanks for posting this! 

It looks like in your dcesrv_drsuapi_DsGetNCChanges() call you do a
full search of the directory every time, pulling all records?

Just using a search of (uSNChanged>=N) would be a big improvement in
terms of memory consumption. It will still be slow in the backend, as
the tdb backend doesn't actually use the indexes for a >= search, but
at least the DRS server wouldn't have to parse all the records. 

Cheers, Tridge