Thanks for the explanation. It makes sense but I am hoping that you can clarify things a bit more ..
so now it sounds like in solrcloud the concept of cores have changed a bit .. as you explained that for me to have 2 cores with different schemas I will need 2 different collections .. and one good thing about solrcores was that you could create new ones with coreadmin api or the http calls .. to create new collections its not that automated right .. secondly if collections represent what kind of used to be solrcore then once i have a collection .. why would i ever want to add multiple cores to it .. i mean i am trying to think of a reason why it would make sense to do that. Thanks On Wed, Feb 8, 2012 at 4:41 PM, Mark Miller <markrmil...@gmail.com> wrote: > > On Feb 8, 2012, at 5:26 PM, Adeel Qureshi wrote: > > > okay so after reading Bruno's blog post .. lets add slice to the mix as > > well .. so we have got collections, cores, shards, partitions and slices > :) > > .. > > Yeah - heh - this has bugged me, but we have not really all come down on > agreement of terminology here. I was a fan of using shard for each node and > slice for partition. Another couple of committers wanted partitions rather > than slice. Another says slice in code, shard for both in terminology and > use context... > > I'd even go for shards as partitions and replicas for every node in a > shard. But those fine points are still settling ;) > > > > > The whole point with cores is to be able to have different schemas on the > > same solr server instance. So how does that changes with collections .. > may > > be an example might help .. if I want to setup a solrcloud cluster with 2 > > cores (different schema) .. with each core having 2 shards (i m assuming > > shards are really partitions here, across multiple nodes in the cluster) > .. > > with one shard being the replica.. > > So this would mean you want to create 2 collections. Think of a collection > as a bunch of SolrCores that all share the same schema and config. > > So you would start up 2 nodes set to one collection and with numShards=1 > that will give you one shard hosted by two identical SolrCores, giving you > a replication factor. The full index will be in each of the two SolrCores. > > Then if you start another two nodes and specify a different collection > name, you will get the same thing, but distinct from your first collection > (although, if both collections have compatible shema/config you can still > search across them). > > > > > > > On Wed, Feb 8, 2012 at 11:35 AM, Mark Miller <markrmil...@gmail.com> > wrote: > > > >> > >> On Feb 8, 2012, at 10:31 AM, Adeel Qureshi wrote: > >> > >>> I have been using solr for a while and have recently started getting > into > >>> solrcloud .. i am a bit confused with some of the concepts .. > >>> > >>> 1. what exactly is the relationship between a collection and the core > .. > >>> can a core has multiple collections in it .. in this case all > collections > >>> within this core will have the same schema .. and i am assuming all > >>> instances of collections within the core can be deployed on different > >> solr > >>> nodes to achieve distributed search .. > >>> or is it the other way around where a collection can have multiple > cores > >> > >> Currently, a core basically equals a replica of the index. > >> > >> So you might have a collection called collection1 - lets say it's 2 > shards > >> and each shard has a single replica: > >> > >> Collection1 > >> shard1 replica1 > >> shard1 replica2 > >> shard2 replica1 > >> shard2 replica2 > >> > >> Each of those replicas is a core. So a collection has multiple cores > >> basically. Also, each of those cores can be on a different machine. So > yes, > >> you have distributed indexing and distributed search. > >> > >>> > >>> 2. at some places it has been pointed out that solrcloud doesnt > actually > >>> supports replication .. but in the solrcloud wiki the second example is > >>> supposed to be for replication .. so does solrcloud at this point > >> supports > >>> automatic replication where as you add more servers it automatically > uses > >>> the additional servers as replicas > >> > >> SolrCloud doesn't support the old style Solr replication concept. It > does > >> however, handle replication - it's just all pretty much automatic and > >> behind the scenes - eg all the information about Solr replication in the > >> wiki documentation for previous versions of Solr is really not > applicable. > >> We now achieve replica copies by sending documents to each shard one > >> document at a time so that we can support near realtime search. The old > >> style replication is only used in recovery, or when you start a new > replica > >> machine and it has to 'catchup' to the other replicas. > >> > >>> > >>> I have a few more questions but I wanted to get these basic ones out of > >> the > >>> way first .. I would appreciate any response. > >> > >> Fire away. > >> > >>> > >>> Thanks > >>> Adeel > >> > >> - Mark Miller > >> lucidimagination.com > >> > >> > >> > >> > >> > >> > >> > >> > >> > >> > >> > >> > > - Mark Miller > lucidimagination.com > > > > > > > > > > > >
