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Per Steffensen edited comment on SOLR-4114 at 11/28/12 11:20 AM: ----------------------------------------------------------------- bq. As far as terminology, when I say replicationFactor of 3, I mean 3 copies of the data. I also count the leader as a replica of a shard (which is logical). It follows from the clusterstate.json, which lists all "replicas" for a shard and one of them just has a flag indicating it's the leader. This also makes it easier to talk about a shard having 0 replicas (meaning there is not even a leader). I understand that you can view all shards under a slice as a "replica", but in my mind "replica" is also a "role" that a shard plays at runtime - all shards except one under a slice play the "replica role" at runtime, the remaining shard plays the "leader role" at runtime. To not create to much confusion, I suggest you use the term "shards" for all the instances under a slice, and that you use the terms "replica" and "leader" only for a role that a shard plays at runtime. But that of course would require changes e.g. to Slice-class where e.g. getReplicas, getReplicasCopy and getReplicasMap needs to me renamed to getShardsXXX. It probably shouldnt be done now, but as a part of a cross-code cleaning up in term-usage. Today there is a heavy mixup of term-usage in the code - replica and shard are sometimes used for a node, replica and shard are used for the same thing, etc. Suggested terms: * collection: A big logical bucket to fill data into * slice: A logical part of a collection. A part of the data going into a collection goes into a particular slice. Slices for a particular collection are non-overlapping * shard: A physical instance of a slice. Running without replica there is one shard per slice. Running with replication-factor X there are X+1 shards per slice. * replica and leader: Roles played by shards at runtime. As soon as the system is not running there are no replica/leader - there are just shards * node-base-url: The prefix/base (up to and including the webapp-context) of the URL for a specific Solr server * node-name: A logical name for the Solr server - the same as node-base-url except /'s are replaced by _'s and the protocol part (http(s)://) is removed was (Author: steff1193): bq. As far as terminology, when I say replicationFactor of 3, I mean 3 copies of the data. I also count the leader as a replica of a shard (which is logical). It follows from the clusterstate.json, which lists all "replicas" for a shard and one of them just has a flag indicating it's the leader. This also makes it easier to talk about a shard having 0 replicas (meaning there is not even a leader). I understand that you can view all shards under a slice as a "replica", but in my mind "replica" is also a "role" that a shard plays at runtime - all shards except one under a slice plays the "replica role" at runtime, the remaining shard play the "leader role". To not create to much confusion I suggest you use the term shards for all the instances under a slice, and that you use the term "replica" only for a role that a shard plays at runtime. But that of course would require changes e.g. to Slice-class where e.g. getReplicas, getReplicasCopy and getReplicasMap needs to me renamed to getShardsXXX. It probably shouldnt be done now, but as a part of a cross-code cleaning up in term-usage. Suggested terms: * collection: A big logical bucket to fill data into * slice: A logical part of a collection. A part of the data going into a collection goes into a particular slice. Slices for a particular collection are non-overlapping * shard: A physical instance of a slice. Running without replica there is one shard per slice. Running with replication-factor X there are X+1 shards per slice. * replica and leader: Roles played by shards at runtime. As soon as the system is not running there are no replica/leader - there are just shards * node-base-url: The prefix/base (up to and including the webapp-context) of the URL for a specific Solr server * node-name: A logical name for the Solr server - the same as node-base-url except /'s are replaced by _'s and the protocol part (http(s)://) is removed > Collection API: Allow multiple shards from one collection on the same Solr > server > --------------------------------------------------------------------------------- > > Key: SOLR-4114 > URL: https://issues.apache.org/jira/browse/SOLR-4114 > Project: Solr > Issue Type: New Feature > Components: multicore, SolrCloud > Affects Versions: 4.0 > Environment: Solr 4.0.0 release > Reporter: Per Steffensen > Assignee: Per Steffensen > Labels: collection-api, multicore, shard, shard-allocation > Attachments: SOLR-4114.patch > > > We should support running multiple shards from one collection on the same > Solr server - the run a collection with 8 shards on a 4 Solr server cluster > (each Solr server running 2 shards). > Performance tests at our side has shown that this is a good idea, and it is > also a good idea for easy elasticity later on - it is much easier to move an > entire existing shards from one Solr server to another one that just joined > the cluter than it is to split an exsiting shard among the Solr that used to > run it and the new Solr. > See dev mailing list discussion "Multiple shards for one collection on the > same Solr server" -- This message is automatically generated by JIRA. 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