Thank you for answering. Indeed, I do keep a "running count" and I use MapRed to compute the extent of a property (of a kind).
Recently I watched again the Google I/O video w/ Brett Slatkin where he talks about self-join, and the zig-zag algorithm in about minute 27 into that video. Indexes need to store all values, and ordered as well. Depending on index table implementation it could be easy to retrieve the set of values. It is not a very big deal -- just wanted to avoid maintaining extents explicitly. On Dec 21, 1:38 pm, "Ikai Lan (Google)" <ikai.l+gro...@google.com> wrote: > No, we can't know all possible values without traversing the entire index. > Your best bet is to keep a "running count" - when someone enters a new > color, save it. If you need to generate this data based on existing > properties, I would suggest appengine-mapreduce > (http://code.google.com/p/appengine-mapreduce). > > -- > Ikai Lan > Developer Programs Engineer, Google App Engine > Blogger:http://googleappengine.blogspot.com > Reddit:http://www.reddit.com/r/appengine > Twitter:http://twitter.com/app_engine > > On Tue, Dec 21, 2010 at 9:22 AM, jacek.ambroziak > <jacek.ambroz...@gmail.com>wrote: > > > > > > > > > Say, I have a set of Person Entities with List<String> favoriteColor > > property. > > People can specify their own sets of colors for that property. > > > Can I access the union of these color sets, ie. all the values they have > > entered > > for this property? The values should sit in the DataStore index, ordered, > > but can we access such data? > > > -- > > You received this message because you are subscribed to the Google Groups > > "Google App Engine for Java" group. > > To post to this group, send email to > > google-appengine-j...@googlegroups.com. > > To unsubscribe from this group, send email to > > google-appengine-java+unsubscr...@googlegroups.com<google-appengine-java%2B > > unsubscr...@googlegroups.com> > > . > > For more options, visit this group at > >http://groups.google.com/group/google-appengine-java?hl=en. -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
