Hi Tim thank you very much for the link, very interesting project! just too bad that there is no backend for the app engine datastore available yet...
you are absolutely right, the query/fetch restrictions will probably cause problems for items with a very large number of triples. my goal is to find a generic solution for this problem, because i just don't want to add additional logic for this special case. On May 5, 2:09 am, Tim Hoffman <zutes...@gmail.com> wrote: > Hi > > If you are interested in triplestores (quadstore), you might also want > to have a look at python implementation rdflib (http://www.rdflib.net/) > it is pretty simple to create backend store's for it (it already has > backends for zodb, mysql, sqlite, in memory, etc). > You will find you won't be able to use their sparql processor as its > is built on 'c'. > > The main problems I see with triple stores will be querying. > Appengine query/fetch restrictions will mean that a > big graphs that are expensive may not be possible to retrieve. So what > you can do with it will be very application dependant. > > T > > On May 4, 4:35 pm, Remo <remo.siegw...@gmail.com> wrote: > > > > > > > Hi, > > for my new project, i am thinking of using the datastore as kind of a > > triple store (or tuple store). the idea is based on graphd, the tuple > > store behind freebase (please > > seehttp://blog.freebase.com/2008/04/09/a-brief-tour-of-graphd/ > > for more info). > > > my simplified model would be something like this: > > > class Item(db.Model): > > name = db.StringProperty() > > > class Triple(db.Model): > > from_item = db.ReferenceProperty(Item, > > collection_name='from_triples') > > type = db.ReferenceProperty(TripleType) > > to_item = db.ReferenceProperty(Item, collection_name='to_triples') > > value = db.StringProperty() > > prev_triple = > > db.SelfReferenceProperty(collection_name='next_triple') > > > - a triple can either have a to_item or a value > > - once written, triples are read-only (log-structured, append-only) > > - to modify or delete a triple, a new triple is written with > > prev_triple pointing to the previous triple > > - the number of items at the beginning is small, but could grow up to > > multiple millions > > - most items have between 10 and 50 related (active) triples, but an > > item should be able to scale up to 100'000 triples > > > i am thinking of putting an item with all related triples into the > > same entity group, but are there any side effects or limitations when > > using a large number of different entity groups? > > > the most frequent queries would be: > > - show a single item with all related (active) triples > > - show all items that have a active triple to another specific item or > > with a specific value > > > do you have any experience or ideas/suggestions for implementing this > > kind of triple store in GAE? how would you improve my model by > > applying common optimization techniques like relation index entities? > > > thank you in advance for your feedback and please keep up the good > > work! > > > -- > > You received this message because you are subscribed to the Google Groups > > "Google App Engine" group. > > To post to this group, send email to google-appeng...@googlegroups.com. > > To unsubscribe from this group, send email to > > google-appengine+unsubscr...@googlegroups.com. > > For more options, visit this group > > athttp://groups.google.com/group/google-appengine?hl=en. > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine" group. > To post to this group, send email to google-appeng...@googlegroups.com. > To unsubscribe from this group, send email to > google-appengine+unsubscr...@googlegroups.com. > For more options, visit this group > athttp://groups.google.com/group/google-appengine?hl=en. -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to google-appeng...@googlegroups.com. To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
