I'm trying to build a basic understanding of how indexing and searching works, hopefully someone can either point me to good resources or explain! I'm trying to figure out what having multiple "coordinator" nodes as defined in the elasticsearch.yml would do, and what having multiple "search load balancer" nodes would do. Both in the context of indexing and searching. Is there a functional difference between a "coordinator" node and a "search load balancer" node, beyond the fact that a "search load balancer" node can't be elected master?
Say I have a 4 node cluster. There's a master only "coordinator" node, that doesn't store data, named "master". node.master: true node.data: false There are three data only nodes, "A", "B" and "C" node.master: false node.date: true I have an index "test" with two shards and one replica. Primary shard 0 lives on A, primary shard 1 lives on C, replica shard 0 lives on B, replica shard 1 lives on A. I send the command curl -XPOST http://master:9200/test/test -d '{"foo":"bar"}' A connection is made to master, and the data is sent to master to be indexed. Master randomly decides to place this document in shard 1, so it gets sent to the primary shard 1 on C and replica shard 1 on B, right? This is where routing can come in, I can say that that document really should go to shard 0 because I said so. So this is a fairly simple scenario, assuming I'm correct. What benefit do I get to indexing when I add more "coordinator" nodes? node.master: true node.data: false What about if I add "search load balancer" nodes? node.master: false node.data: false How about on the searching side of things? I send a search to master, curl -XPOST http://master:9200/test/test/_search -d '{"query":{"match_all":{}}}' Master sends these queries off to A, B and C, who each generate their own results and return them to master. Each data node queries all the relevant shards that are present locally and then combines those results for delivery to master. Do only primary shards get queried, or are replica shards queried too? Master takes these combined results from all the relevant nodes and combines them into the final query response. Same questions: What benefit do I get to searching when I add more nodes that are like master? node.master: true node.data: false What about if I add "search load balancer" nodes? node.master: false node.data: false Is the only difference between a node.master: true node.data: false and a node.master: false node.data: false that the node is a candidate to be a master, should it be elected? -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to elasticsearch+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/elasticsearch/eaff1d85-1e85-422d-bfba-9a0825ed5da9%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
