Storage isn't too much of a problem, 12.5 M since a Lucene Filter is just a BitSet, one bit per document. (plus some trivial overhead).
Computational costs... only you know..... But, is every user allowed individual permissions or are users part of groups that have permissions? Filters have logical operators (well, actually it's the bitset that has operators), so you may be able to save a bunch of time by calculating group permissions instead and using the relevant AND/OR/NOT operators. Assuming your permissions are additive, this becomes something like... Calculate a filter for each group for each user for each group the user is in, or in the relevant group filter or in the users individual permissions store the filter away. endfor Then simply add the users filter to a BooleanQuery (MUST) that you use when you search. Don't know if this help much or not, but it's an idea <G>. Best Erick On 4/3/07, Jonathan O'Connor <[EMAIL PROTECTED]> wrote:
Michael, as usual its never so easy! Some users can see almost all documents, and some other users can see very few. I did find an interesting document that describes the problem (but offers no solutions :-() http://www.ideaeng.com/pub/entsrch/v3n4/article01.html. This article talks about early and late binding of security information. Early binding is faster, but harder to implement. And of course, I implemented the easier one. I'm going to see what the computational and storage cost will be if I precalculate this info. Ciao, Jonathan O'Connor XCOM Dublin [image: Inactive hide details for "Michael D. Curtin" <[EMAIL PROTECTED]>]"Michael D. Curtin" <[EMAIL PROTECTED]> *"Michael D. Curtin" <[EMAIL PROTECTED]>* 03/04/2007 15:28 Please respond to java-user@lucene.apache.org To java-user@lucene.apache.org cc Subject Re: Design Problem: Searching large set of protected documents Jonathan O'Connor wrote: > I have a database of a million documents and about 100 users. The documents > can have an access control list, and there is a complex, recursive > algorithm to say if a particular user can see a particular document. > > My problem is that my search algorithm is to first do a standard lucene > search for matching documents, and then check security on each one found, > just returning the allowed documents. However, if I do this, and the lucene > returns 100000 docs, but the user can only see 10 of these, then obviously > the search is going to take an awful long time. > > Has anyone come across this problem before, and if so what approach did you > take? I guess I could precalculate the permissions for every user-document > pair, but that's alot of storage, and a lot of precalculation! My knee-jerk reaction is to suggest a simpler document security model, but I'm guessing that that option isn't available to you. In your example the security attributes of a document are far more discriminating than the query terms. If that relationship is indicative of most of your users and most of the documents, the users and documents aren't updated much, and you have a lot of searching to do, precalculation (results into an additional document field) seems the way to go. It might even turn out that, if you start from a presumption of calculating every user--document security attribute, you come up with an algorithm that is much more efficient than a one-off, can-this-user-see-this-document type of algorithm. Precalculation isn't necessarily a bad thing. Often, it's quite beneficial -- for example, the indexing process itself is a pretty substantial precalculation step! If this seems unwieldy or impractical for some reason, perhaps you could post more attributes of your situation, such as user and data update and addition frequency, query attributes and frequency, and so on. --MDC --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] *** XCOM AG Legal Disclaimer *** Diese E-Mail einschliesslich ihrer Anhaenge ist vertraulich und ist allein für den Gebrauch durch den vorgesehenen Empfaenger bestimmt. Dritten ist das Lesen, Verteilen oder Weiterleiten dieser E-Mail untersagt. Wir bitten, eine fehlgeleitete E-Mail unverzueglich vollstaendig zu loeschen und uns eine Nachricht zukommen zu lassen. This email may contain material that is confidential and for the sole use of the intended recipient. Any review, distribution by others or forwarding without express permission is strictly prohibited. If you are not the intended recipient, please contact the sender and delete all copies. Hauptsitz: Bahnstrasse 37, D-47877 Willich, USt-IdNr.: DE 812 885 664 Kommunikation: Telefon +49 2154 9209-70, Telefax +49 2154 9209-900, www.xcom.de Handelsregister: Amtsgericht Krefeld, HRB 10340 Vorstand: Matthias Albrecht, Renate Becker-Grope, Marco Marty, Dr. Rainer Fuchs Vorsitzender des Aufsichtsrates: Stephan Steuer
