Ayende @ Rahien

Ayende Rahien commented on Modeling hierarchical structures in RavenDB

Tue, 20 Jul 2010 11:18:55 GMT

Martin, Changing username is a rare occasion, you can handle that as a background process

Ayende Rahien commented on Modeling hierarchical structures in RavenDB

Tue, 20 Jul 2010 11:18:02 GMT

Martin, Yes, you can. You create an index that project those out, and then query on that

Martin commented on Modeling hierarchical structures in RavenDB

Wed, 14 Jul 2010 22:55:36 GMT

... and what happens if a Username is stored for every Answer as it always needs to be displayed, but the user is allowed to change his Username ? Will i have to loop through all documents in the database where the Username is stored (almost everywhere there is a user action), and update the Username? will it be a problem ? Thanks for a great blog.

Martin commented on Modeling hierarchical structures in RavenDB

Wed, 14 Jul 2010 22:48:49 GMT

Is there a way to only load a small part of the Answers for paging (etc if there will be hundreds or thousands of them) soo the database wont have to send all of them ?

Ayende Rahien commented on Modeling hierarchical structures in RavenDB

Mon, 28 Jun 2010 13:07:15 GMT

Sebastian, It shouldn't be very expensive.

sebastien commented on Modeling hierarchical structures in RavenDB

Mon, 28 Jun 2010 11:46:01 GMT

What would be the cost of updating name in partialy denormalized reference ?

Daniel Cohen commented on Modeling hierarchical structures in RavenDB

Fri, 25 Jun 2010 13:50:46 GMT

@Matt warren , I get this if you go with the bare reference approach and then in you POCO class you have a string ParentId { get;set;} but in the denormalized way what kind of class you get in return ?? it's not an id field nor a full Person class btw "c# model" was intended to be the title not the name, a funny mistake :)

Matt Warren commented on Modeling hierarchical structures in RavenDB

Thu, 24 Jun 2010 10:18:36 GMT

Just to add: Load is a generic method that need to have the type specified as "Person", but it got stripped out in my answer.

Matt Warren commented on Modeling hierarchical structures in RavenDB

Thu, 24 Jun 2010 10:16:44 GMT

@c# model You can use the id string and load the document based on that, i.e. var person = session.Load

c# model commented on Modeling hierarchical structures in RavenDB

Thu, 24 Jun 2010 04:39:48 GMT

maybe i'm missing something here but the Person denormalized example saves only id and name. When you query the model how does children and parent convert back to a whole c# person (with own parent and children) ?

DavidChan commented on Modeling hierarchical structures in RavenDB

Thu, 24 Jun 2010 03:01:11 GMT

seems like client api doesnot support the command "patch" ,right?

Ayende Rahien commented on Modeling hierarchical structures in RavenDB

Wed, 23 Jun 2010 15:21:37 GMT

Jason, Yes... Although I would put it differently

Brian Vallelunga commented on Modeling hierarchical structures in RavenDB

Wed, 23 Jun 2010 15:19:45 GMT

Ahh, thanks, I see now. I read that as only being available with replication. Reading the mailing list, it seems there is client support at the store level for this. I haven't seen any examples of it though. I'll go ahead and ask on the list.

Jason Young commented on Modeling hierarchical structures in RavenDB

Wed, 23 Jun 2010 15:13:59 GMT

Interesting! So... for a limitlessly recursive heirarchy (e.g. parent-child relationship), you want each element in its own document, but for depth-limited relationships (e.g. question-answer), you can put all the "children" in a collection in the "parent" document, and "children" need not have documents of their own, correct? If so, that makes sense to me.

Ayende Rahien commented on Modeling hierarchical structures in RavenDB

Wed, 23 Jun 2010 14:33:10 GMT

Brian, As I told Nathan, the answer for that is to use Raven's partial document update support, which would resolve the issue

Brian Vallelunga commented on Modeling hierarchical structures in RavenDB

Wed, 23 Jun 2010 14:30:34 GMT

I have a similar question to Nathan's. Given the StackOverflow model you presented, if two people answer the question at about the same time, won't you get conflicts storing the data to the db. I can imagine the following scenario: 1) Person A answers question. 2) Get question document for Person A 3) Append answer A 4) Person B answers question. 5) Get question document for Person B 6) Save Person A's answer to DB. 7) Append answer B 8) Save Person B's answer to DB. If we let the last-in win, Person A's answer is completely gone. I've actually avoided working a part of my application that requires this sort of modeling because I haven't figured out what to do yet. Obviously storing the answers as entities themselves would help, but we'd almost always want to access the data as one document in this situation. Can you expand on a strategy here? Thanks

Ayende Rahien commented on Modeling hierarchical structures in RavenDB

Wed, 23 Jun 2010 14:02:36 GMT

[ravendb.net/documentation/docs-http-api-patch](http://ravendb.net/documentation/docs-http-api-patch)

Nathan Stott commented on Modeling hierarchical structures in RavenDB

Wed, 23 Jun 2010 13:41:11 GMT

How do the partial updates work? Does the app have to specify that it is doing a partial update or does Raven do this behind the scenes? Got a link handy?

Ayende Rahien commented on Modeling hierarchical structures in RavenDB

Wed, 23 Jun 2010 13:38:00 GMT

Nathan, That is a good point. WRT replication, Raven would be in the same situation as CouchDB, but Raven also support the notion of partial updates, things like: "Add this answer to the Answers array" Which means that two concurrent updates can both succeed.

Nathan Stott commented on Modeling hierarchical structures in RavenDB

Wed, 23 Jun 2010 13:19:21 GMT

In CouchDB, you would not want to embed the answers to a question directly in the document because if two people answered the question at about the same time, or if you were using replication and they answered it between replication cycles, then you would get a 409 (conflict). If you add the answers as documents of their own, two people adding at the same time will not cause conflicts. Would this scenario not be a problem with RavenDB? What about RavenDB makes the proper choice of strategy different?