noblepaul commented on code in PR #996: URL: https://github.com/apache/solr/pull/996#discussion_r965472003
########## solr/solr-ref-guide/modules/deployment-guide/pages/node-roles.adoc: ########## @@ -66,15 +69,37 @@ A node with this role (in mode "on") can host shards and replicas for collection === `overseer` role A node with this role can perform duties of an overseer node (unless mode is `disallowed`). When one or more nodes have the overseer role in `preferred` mode, the overseer leader will be elected from one of these nodes. In case no node is designated as a preferred overseer or no such node is live, the overseer leader will be elected from one of the nodes that have the overseer role in `allowed` mode. If all nodes that are designated with overseer role (allowed or preferred) are down, the cluster will be left without an overseer. +=== `coordinator` role + +A node with this role can act as if it has replicas of all collections in the cluster when a query is performed. The workflow is as follows + +If the cluster has collections with very large no:of shards, performing distributed requests in your _`data node`_ will lead to + +* large heap utilization +* frequent GC pauses + +In such cases, a few dedicated nodes can be started with a *`coordinator`* role and queries can be sent to that node and avoid intermittent and unpredictable load in data nodes. The coordinator node is stateless and does not host any data. So, we can create and destroy coordinator nodes without any data loass or down time. Review Comment: >Which client needs to be used to send queries to coordinator nodes? Client support is not yet added as part of this PR. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
