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2979582 - Recommended number of shards and replicas in SOLR Cloud, what is a collection/core/shard/replica


In Solr terminology, there is a sharp distinction between the logical parts of an index (collections, shards) and the physical manifestations of those parts (cores, replicas). In this diagram, the "logical" concepts are dashed/transparent, while the "physical" items are solid.

SearchStax Solr Glossary


A production deployment is usually a cluster of two or more Solr nodes coordinated by a Zookeeper ensemble (not shown).

Zookeeper ensures that changes to config files and updates to indexes are automatically distributed across the nodes of the cluster.


A single instance of Solr. In deployments, one node corresponds to one physical server or pod


A single logical index in its entirety, regardless of how many replicas or shards it has. One Solr node can serve multiple collections.


logical subset of the documents in a collection. Clients don't usually subdivide their collections, so for practical purposes a "shard" and a "collection" are the same thing.

Core and Replica:

A complete physical index on a node. In a typical collection, a "core" is the same thing as a "replica."



SOLR Cloud


KBA , CEC-COM-CPS-SER , Search , Problem

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