Hi Norbert, for me the gain within smalltalk is huge because I want to navigate from person to trip and from trip to person by the attributes without asking mongo for the correspondent object via indexes.
Don't you think that this is a question of design of the object model and should not be decided by database arguments? Regards Sabine On Thu, Apr 17, 2014 at 3:40 PM, NorbertHartl [via Smalltalk] < [email protected]> wrote: > Sabine, > > I read the case now the first time. Just one note. Having references in > both directions is probably not the best idea if using a non-object store. > For navigating the graph it might be good but for persisting it is not. The > serialization is a lot more complex if you do and the gain is nothing. For > most databases with proper indexes you can request both directions easily > and fast. So having one reference pointing from A to B you get the opposite > direction for free. > > Norbert > > Am 17.04.2014 um 15:22 schrieb Sabine Knöfel <[hidden > email]<http://user/SendEmail.jtp?type=node&node=4755102&i=0> > >: > > Hi Olivier, > > possibly the option > VOMongoContainer>>enableMissingContent; > is useful to avoid > > http://forum.world.st/Voyage-image-freeze-VOMongoError-Lazy-reference-not-found-td4703739.html > > Here is an example: > http://esug.org/data/ESUG2013/4-Thu/03-ESUG2013%20-%20VoyageTutorial.pdf > > Regards > Sabine > > > > > On Thu, Apr 17, 2014 at 3:07 PM, Olivier Auverlot [via Smalltalk] <<a > href="x-msg://56/user/SendEmail.jtp?type=node&node=4755097&i=0" > target="_top" rel="nofollow" link="external">[hidden email]> wrote: > >> thanks Robert for the explications. >> >> I agree with you that's the best way to remove a book is to delete the >> reference in ComicsCollection. >> >> But how to do that ? Must I simply remove the reference in the ordered >> collection ? Voyage will syncronize automatically the data in memory with >> the content of the database ? Must I force the save of the data after >> removing the reference ? >> >> Olivier ;-) >> >> >> 2014-04-17 14:10 GMT+02:00 Norbert Hartl <[hidden >> email]<http://user/SendEmail.jtp?type=node&node=4755092&i=0> >> >: >> >> >>> Am 17.04.2014 um 13:53 schrieb olivier <[hidden >>> email]<http://user/SendEmail.jtp?type=node&node=4755092&i=1> >>> >: >>> >>> > Hi, >>> > >>> > I'm using Voyage in a Pharo application. >>> > >>> > I have two MongoDB collections which are ComicsCollection and >>> ComicsBook. Each book is attached to a instance of ComicsCollection. The >>> reference of each book is stored in an ordered collection (in the instance >>> of ComicsCollection). The problem is that if I remove a book, the reference >>> to the book is not deleted from ComicsCollection. >>> > >>> > How can I remove properly a book and the reference to the book ? >>> > >>> From the smalltalk image view the problem is usually exactly the >>> opposite: You don’t delete objects but you remove references to them. As >>> voyage maps objects it is a good idea to stay in the object realm. So you >>> should rather remove the book from the collection. This way you won’t get >>> errors just garbage. The „real“ problem that arises then is that the book >>> would still be in the database. Just like it is in the image but there is >>> no garbage collector for mongo. To decide that from the image is not >>> possible. You load only a sub graph from the database into image memory. So >>> you don’t know if there are other objects referencing the book. >>> >>> If your records fit all in memory you could load all collections and >>> books and build the difference between all referenced books in the >>> collections and the total amount of books. The difference will be the set >>> of objects not being referenced by a collection and those can be deleted. >>> >>> If the records do not fit in memory an alternative strategy would be >>> needed. I started to research if it is possible to build a map/reduce based >>> garbage collector for common cases but got distracted. But I have the same >>> problem so I will need to pick it up some time. >>> >>> hope that helps, >>> >>> Norbert >>> >>> >>> >> >> >> ------------------------------ >> If you reply to this email, your message will be added to the >> discussion below: >> >> http://forum.world.st/Voyage-how-to-delete-references-to-objects-tp4755088p4755092.html >> To start a new topic under Pharo Smalltalk Users, email <a >> href="x-msg://56/user/SendEmail.jtp?type=node&node=4755097&i=1" >> target="_top" rel="nofollow" link="external">[hidden email] >> To unsubscribe from Pharo Smalltalk Users, click here. >> NAML<http://forum.world.st/template/NamlServlet.jtp?macro=macro_viewer&id=instant_html%21nabble%3Aemail.naml&base=nabble.naml.namespaces.BasicNamespace-nabble.view.web.template.NabbleNamespace-nabble.view.web.template.NodeNamespace&breadcrumbs=notify_subscribers%21nabble%3Aemail.naml-instant_emails%21nabble%3Aemail.naml-send_instant_email%21nabble%3Aemail.naml> >> > > > ------------------------------ > View this message in context: Re: Voyage: how to delete references to > objects.<http://forum.world.st/Voyage-how-to-delete-references-to-objects-tp4755088p4755097.html> > Sent from the Pharo Smalltalk Users mailing list > archive<http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html>at > Nabble.com. > > > > > ------------------------------ > If you reply to this email, your message will be added to the discussion > below: > > http://forum.world.st/Voyage-how-to-delete-references-to-objects-tp4755088p4755102.html > To start a new topic under Pharo Smalltalk Users, email > [email protected] > To unsubscribe from Pharo Smalltalk Users, click > here<http://forum.world.st/template/NamlServlet.jtp?macro=unsubscribe_by_code&node=1310670&code=c2FiaW5lLmtub2VmZWxAZ21haWwuY29tfDEzMTA2NzB8MTA0OTM5MTYx> > . > NAML<http://forum.world.st/template/NamlServlet.jtp?macro=macro_viewer&id=instant_html%21nabble%3Aemail.naml&base=nabble.naml.namespaces.BasicNamespace-nabble.view.web.template.NabbleNamespace-nabble.view.web.template.NodeNamespace&breadcrumbs=notify_subscribers%21nabble%3Aemail.naml-instant_emails%21nabble%3Aemail.naml-send_instant_email%21nabble%3Aemail.naml> > -- View this message in context: http://forum.world.st/Voyage-how-to-delete-references-to-objects-tp4755088p4755106.html Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.
