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Going forward, once SOLR-15715 is introduced, there would be a distinct role for coordinator nodes. These nodes can be used as query aggregations for distributed requests or streaming expressions and possibly also (later) distributed indexing. This provides for a clean mechanism for users to specify which are the data nodes (stateful) and which are coordinator nodes (stateless), and hence employing heterogeneous deployment strategies.

Scope of this SIP

• Concept of roles
• Defining a "data" role
• Role API and config
• Not in scope, but tangentially related: SOLR-15715 and SIP-14, two upcoming features that can leverage node roles.

Proposal

Every node in Solr has one or more “roles”. The following roles are proposed:

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