http://ayende.comAyende @ RahienCopyright (C) Ayende Rahien 2004 - 2021 (c) 202660Bob, that depends on how you setup the system. You can do sharding AND replication that means that you have a second node ready to work if the first one is down.http://ayende.com/155297/ravendb-sharding-blind-sharding#comment14http://ayende.com/155297/ravendb-sharding-blind-sharding#comment14Mon, 09 Apr 2012 18:14:52 GMTWhat happens when when of the shards goes down, especially the first one? Will another shard take over the hilo duties?http://ayende.com/155297/ravendb-sharding-blind-sharding#comment13http://ayende.com/155297/ravendb-sharding-blind-sharding#comment13Mon, 09 Apr 2012 14:43:45 GMTHendry, Cross docs transactions till work, yes. As you'll see today in the next post, we handle things in such a fashion that we have great locality of reference, so most of those features just work. Things like Unique Constraints cannot work in this fashion, because they assume they have access to the entire data set, but there are other things that can be doe to make this workhttp://ayende.com/155297/ravendb-sharding-blind-sharding#comment12http://ayende.com/155297/ravendb-sharding-blind-sharding#comment12Tue, 20 Mar 2012 06:49:40 GMTOne of RavenDb's selling points is cross-document transactions. Would this still work in a sharded setup? And likewise with data constraints (such as unique-constraint). Also, will it be possible to configure your sharding in a routing server (like mongos) rather than within each client?http://ayende.com/155297/ravendb-sharding-blind-sharding#comment11http://ayende.com/155297/ravendb-sharding-blind-sharding#comment11Tue, 20 Mar 2012 02:10:46 GMTHow easy is it to go from blind sharding to a specialized sharding strategy later? Seems like it would be easier to figure out your sharding strategy right away based on the load points of your single RavenDB instance and do sharding properly from the beginning.http://ayende.com/155297/ravendb-sharding-blind-sharding#comment10http://ayende.com/155297/ravendb-sharding-blind-sharding#comment10Mon, 19 Mar 2012 16:10:32 GMTDaniel, You _are_ correct with regards to that, sure. Except that you are missing tomorrow's post, which deals with that. But even so, you are still not considering an important fact. Blind sharding is super important to let you start playing with sharding, without a big hurdle of the initial costhttp://ayende.com/155297/ravendb-sharding-blind-sharding#comment9http://ayende.com/155297/ravendb-sharding-blind-sharding#comment9Mon, 19 Mar 2012 15:25:51 GMTRafal, Wait for the next post, it discusses how we handle merging queries. :-) And you usually shard based on expected load, rather than actual data size.http://ayende.com/155297/ravendb-sharding-blind-sharding#comment8http://ayende.com/155297/ravendb-sharding-blind-sharding#comment8Mon, 19 Mar 2012 15:24:41 GMTThis is a very nice feature, obviously. However, I'm not sure if it was worth the effort: If someone needs to have sharded instances, then he plays the _big data_ game, which means he will have to put a serious amount of effort into his application and will certainly need to get a very good understanding of RavenDB anyway. Because this simple round-robin won't be sufficient in these situations, he would definitely want to implement his own sharding strategy to have full control over where the documents go. All the others that aren't comfortable writing their own sharding-strategy won't have such demanding applications and therefore only want replication and not sharding if any clustering at all. Altogether, very good job, but if find it unlikely that someone will use it that way.http://ayende.com/155297/ravendb-sharding-blind-sharding#comment7http://ayende.com/155297/ravendb-sharding-blind-sharding#comment7Mon, 19 Mar 2012 15:09:06 GMTthis just makes me drool. http://ayende.com/155297/ravendb-sharding-blind-sharding#comment6http://ayende.com/155297/ravendb-sharding-blind-sharding#comment6Mon, 19 Mar 2012 14:21:33 GMTCan you tell when it's time to switch from single database to sharded? Is it number of records or database size? And another one: how does Ravendb perform queries across shards? I assume it glues the results at the client - is this true? What about paging and sorting then?http://ayende.com/155297/ravendb-sharding-blind-sharding#comment5http://ayende.com/155297/ravendb-sharding-blind-sharding#comment5Mon, 19 Mar 2012 13:02:06 GMT@Damien, hahaha, me too!!!http://ayende.com/155297/ravendb-sharding-blind-sharding#comment4http://ayende.com/155297/ravendb-sharding-blind-sharding#comment4Mon, 19 Mar 2012 11:02:50 GMTIn the first 3 screenshots - I spent far too long trying to work out why you were censoring the available commands - before realising you were underlining the URLs instead.http://ayende.com/155297/ravendb-sharding-blind-sharding#comment3http://ayende.com/155297/ravendb-sharding-blind-sharding#comment3Mon, 19 Mar 2012 09:28:43 GMTItay, You would need to do some migration in order to go there, yes.http://ayende.com/155297/ravendb-sharding-blind-sharding#comment2http://ayende.com/155297/ravendb-sharding-blind-sharding#comment2Mon, 19 Mar 2012 08:34:59 GMTWhat about moving from a non-sharded environment to a sharded environment? Is there a magic solution, or do we need to write or own migration code to pull data from the old environment, and put it in the new environment?http://ayende.com/155297/ravendb-sharding-blind-sharding#comment1http://ayende.com/155297/ravendb-sharding-blind-sharding#comment1Mon, 19 Mar 2012 08:33:21 GMT