I frequently use multiple cores for these reasons: * Completely different applications, such as web search and directory search or if their update latency / query /caching requirements are very different I can then also nuke one without affecting the other Also, you get nice separation for monitoring each app with e.g. NewRelicRPM * Two news collections in different languages, and I don't want the TF/IDF for overlapping terms between the languages destroy relevancy. I then use sharding if we need to return results from both cores
In production we run 3-4 cores on same server without problems. But be aware that you have enough memory for the extra caches and a few more Java objects. -- Jan Høydahl, search solution architect Cominvent AS - www.cominvent.com On 17. feb. 2011, at 00.28, Markus Jelsma wrote: > You can also easily abuse shards to query multiple cores that share parts of > the schema. This way you have isolation with the ability to query them all. > The same can, of course, also be achieved using a sinlge index with a simple > field identying the application and using fq on that one. > >> Yes, you're right, from now on when I say that, I'll say "except >> shards". It is true. >> >> My understanding is that shards functionality's intended use case is for >> when your index is so large that you want to split it up for >> performance. I think it works pretty well for that, with some >> limitations as you mention. >> >> From reading the list, my impression is that when people try to use >> shards to solve some _other_ problem, they generally run into problems. >> But maybe that's just because the people with the problems are the ones >> who appear on the list? >> >> My personal advice is still to try and put everything together in one >> big index, Solr will give you the least trouble with that, it's what >> Solr "likes" to do best; move to shards certainly if your index is so >> large that moving to shards will give you performance advantage you >> need, that's what they're for; be very cautious moving to shards for >> other challenges that 'one big index' is giving you that you're thinking >> shards will solve. Shards is, as I understand it, _not_ intended as a >> general purpose "federation" function, it's specifically intended to >> split an index accross multiple hosts for performance. >> >> Jonathan >> >> On 2/16/2011 4:37 PM, Bob Sandiford wrote: >>> Hmmm. Maybe I'm not understanding what you're getting at, Jonathan, when >>> you say 'There is no good way in Solr to run a query across multiple >>> Solr indexes'. >>> >>> What about the 'shards' parameter? That allows searching across multiple >>> cores in the same instance, or shards across multiple instances. >>> >>> There are certainly implications here (like Relevance not being >>> consistent across cores / shards), but it works pretty well for us... >>> >>> Thanks! >>> >>> Bob Sandiford | Lead Software Engineer | SirsiDynix >>> P: 800.288.8020 X6943 | bob.sandif...@sirsidynix.com >>> www.sirsidynix.com >>> >>>> -----Original Message----- >>>> From: Jonathan Rochkind [mailto:rochk...@jhu.edu] >>>> Sent: Wednesday, February 16, 2011 4:09 PM >>>> To: solr-user@lucene.apache.org >>>> Cc: Thumuluri, Sai >>>> Subject: Re: Solr multi cores or not >>>> >>>> Solr multi-core essentially just lets you run multiple seperate >>>> distinct >>>> Solr indexes in the same running Solr instance. >>>> >>>> It does NOT let you run queries accross multiple cores at once. The >>>> cores are just like completely seperate Solr indexes, they are just >>>> conveniently running in the same Solr instance. (Which can be easier >>>> and >>>> more compact to set up than actually setting up seperate Solr >>>> instances. >>>> And they can share some config more easily. And it _may_ have >>>> implications on JVM usage, not sure). >>>> >>>> There is no good way in Solr to run a query accross multiple Solr >>>> indexes, whether they are multi-core or single cores in seperate Solr >>>> doesn't matter. >>>> >>>> Your first approach should be to try and put all the data in one Solr >>>> index. (one Solr 'core'). >>>> >>>> Jonathan >>>> >>>> On 2/16/2011 3:45 PM, Thumuluri, Sai wrote: >>>>> Hi, >>>>> >>>>> I have a need to index multiple applications using Solr, I also have >>>> >>>> the >>>> >>>>> need to share indexes or run a search query across these application >>>>> indexes. Is solr multi-core - the way to go? My server config is >>>>> 2virtual CPUs @ 1.8 GHz and has about 32GB of memory. What is the >>>>> recommendation? >>>>> >>>>> Thanks, >>>>> Sai Thumuluri
