http://ayende.comAyende @ RahienCopyright (C) Ayende Rahien 2004 - 2021 (c) 202660Chirag, You can't usually replicate information from ravendb to relational. The format doesn't work, that is why you need to specify a transformation function, and that is where we have the index replication, the index provide the transformation function. Going directly the other way is possible, but usually not really recommended, because you WANT to take advantage of the different structure options in RavenDB. Usually, you write some sort of an ETL between the twohttp://ayende.com/136196/when-should-you-use-ravendb#comment15http://ayende.com/136196/when-should-you-use-ravendb#comment15Wed, 21 Dec 2011 09:46:21 GMTThe main blog says "..data is replicated to RavenDB from the main database .." and ".. there is also an additional reporting database as well..". What are the best and proven ways to migrate data to (in first statement) and from (in second statement) RavenDB to relational database say SQL Server? One of the Google Group discussion mentioned about using RavenDB Index Replication (http://ravendb.net/bundles/index-replication) but that seem to be limited to replication of index and not the data. Another discussion mentioned about Rhino ETL (http://ayende.com/blog/3102/rhino-etl-2-0). It will be great if you can give some insight into either of those or other alternatives. Thanks for your help. http://ayende.com/136196/when-should-you-use-ravendb#comment14http://ayende.com/136196/when-should-you-use-ravendb#comment14Mon, 19 Dec 2011 15:17:24 GMTIt would be great if you could share the comparison chart and tests (db, data or script) that shows a scenario where RavenDB is preferable over other RDBMS .. I always want to use RavenDB but it's hard to conceive the mgmt that this little db is better than MSSQL or Oracle that we spent thousands $.. http://ayende.com/136196/when-should-you-use-ravendb#comment13http://ayende.com/136196/when-should-you-use-ravendb#comment13Thu, 15 Dec 2011 03:42:54 GMTThere's one major use case for RavenDB. If you need to create a prototype application in a real hurry, nothing beats RavenDB. Design your objects, stuff it in, query it out and complete your prototype in record time.http://ayende.com/136196/when-should-you-use-ravendb#comment12http://ayende.com/136196/when-should-you-use-ravendb#comment12Wed, 30 Nov 2011 13:26:12 GMT@Kurt You could look at the code that runs Ayende's blog https://github.com/ayende/RaccoonBloghttp://ayende.com/136196/when-should-you-use-ravendb#comment11http://ayende.com/136196/when-should-you-use-ravendb#comment11Wed, 23 Nov 2011 14:42:08 GMTthese days quality of your posts are too low... http://ayende.com/136196/when-should-you-use-ravendb#comment10http://ayende.com/136196/when-should-you-use-ravendb#comment10Tue, 22 Nov 2011 07:05:43 GMTThis is truly new to me. What are some samples of RavenDB based applications?http://ayende.com/136196/when-should-you-use-ravendb#comment9http://ayende.com/136196/when-should-you-use-ravendb#comment9Tue, 22 Nov 2011 05:31:17 GMTI don't intend to rail on you, Joe, or Ayende, but that is an attitude I see frequently on this blog. I completely understand that you can't post a single example as a "best practice", however without any sort of concrete example, these potentially helpful tips remain too ethereal to assist many people. I, and any other developer worth his/her salt, understand that you can't take a single piece of sample code, slather it all over your application, and say "Ayende and Joe told me to do it." However, a concrete example moves the conceptual into reality, and gives one a place to start his investigations. Cargo Cult coders are going to copy and paste no matter what you do, if not from you than someone else. It's Ayende's blog, and he can post whatever he wants, but many times I come here only to be frustrated because nobody wants to steer anyone in the wrong direction. Throw something practical out there and trust that people can manage not to shoot themselves in the foot.http://ayende.com/136196/when-should-you-use-ravendb#comment8http://ayende.com/136196/when-should-you-use-ravendb#comment8Mon, 21 Nov 2011 17:37:22 GMTI agree with Frans Bouma. I know the answer to his question, but it's because I read this blog daily, have read a lot of the RavenDB documentation, follow the google group, and have been using RavenDB on a project. It would be nice to see a list of all the things it solves and why could almost always choose no-sql for OLTP. People that are used to using relational databases don't even understand the benefits until they understand how the objects are broken up differently and how they should be used in RaveDB. You've (Ayende) definitely covered this, but the info is spread out across other blog posts, RavenDB docs, and the group. Maybe just a brief description and a link would suffice.http://ayende.com/136196/when-should-you-use-ravendb#comment7http://ayende.com/136196/when-should-you-use-ravendb#comment7Mon, 21 Nov 2011 17:32:53 GMTBouma, For these types of scenarios there really is no answer, at least not a cut-and-dry one. Ayende says you can use it for OLTP, or as a Persistent View Model Cache, or whatever you please. When and how, however, is ultimately up to you. If you need normalized data with schema as you pointed out, than you probably need an RDMBS. I think Ayende, somewhat subliminally, is making the point that there really is no "best-practice" here and there are many considerations and touch points in deciding between document and relational. In my opinion, one generally does the community a great service when not listing out bullet lists of how and where and when to do things.http://ayende.com/136196/when-should-you-use-ravendb#comment6http://ayende.com/136196/when-should-you-use-ravendb#comment6Mon, 21 Nov 2011 15:50:50 GMTBouma++http://ayende.com/136196/when-should-you-use-ravendb#comment5http://ayende.com/136196/when-should-you-use-ravendb#comment5Mon, 21 Nov 2011 13:06:00 GMTI find the post lacking substantial information: a NoSQL database stores data denormalized, and without schema. These are aspects which are crucial for the data and more importantly, the information that's being distilled from it: an RDBMS stores data normalized and WITH schema. Both have advantages and disadvantages. An article which describes 'when to use a NoSQL database' (in this case RavenDB) IMHO should address these advantages and disadvantages, if the article is about describing when to pick RavenDB over an RDBMS. I.o.w.: the post is useless without that. If your intention was to describe when to pick RavenDB over other NoSQL / Document DBs / OODBs, you should address the advantages of RavenDB over these other choices. Again you don't do that. http://ayende.com/136196/when-should-you-use-ravendb#comment4http://ayende.com/136196/when-should-you-use-ravendb#comment4Mon, 21 Nov 2011 10:55:44 GMTRavenDB is fast compared to an RDBMS for data persistence but is still no match for Redis or Memcached as a distributed cache which both operate in memory, (although Redis can be made to persist to disk). I did some benchmarks a while ago comparing raw write performance of Redis vs RavenDB: http://www.servicestack.net/mythz_blog/?p=474 Redis is used as the distributed cache for all StackOverflow websites because its so fast.http://ayende.com/136196/when-should-you-use-ravendb#comment3http://ayende.com/136196/when-should-you-use-ravendb#comment3Mon, 21 Nov 2011 10:40:18 GMTJonty, That really depend on your scenario. We see RavenDB used to store the view model in aggregated form, already prepared to be consumed. We are storing pretty much all of the information you need for a single page view on a single document, which makes us really fast for rendering complex pages.http://ayende.com/136196/when-should-you-use-ravendb#comment2http://ayende.com/136196/when-should-you-use-ravendb#comment2Mon, 21 Nov 2011 10:32:13 GMTRegarding the persistent view model cache, would you advise using RavenDB in place of a distributed cache, or alongside one? What advantages would you gain over using a persistent distributed cache? Is RavenDB a direct competitor to something like membase (now couchbase)?http://ayende.com/136196/when-should-you-use-ravendb#comment1http://ayende.com/136196/when-should-you-use-ravendb#comment1Mon, 21 Nov 2011 10:18:55 GMT