[hibernate-dev] Hibernate Search connecting to multiple Elasticsearch clusters

[Sanne Grinovero]

Today our experiments are assuming we're connecting to a single
Elasticsearch cluster: one hostname to configure, etc..

I think this is an acceptable limitation for version 5.6 (our first
stable milestone to support this integration) but I'm wondering if we
should document it as a temporary limitation or as an intentional
design.

I think that eventually we should allow having different entities
(indexes) to be stored on different ES clusters; this shouldn't be too
hard to manage as the codebase is already structured around this
capability of having different types in different "indexes"; so while
a single Elasticsearch cluster can manage multiple indexes (that's a
bit of a novel concept) I see no reason to not allow different indexes
to be mapped on different clusters.

= Am I missing some strong reason to not allow this?

= While this will (likely) not be supported in 5.6, should the public
API and configuration properties allow for this to be configured
per-index already? (Changing it later would be a breaking change)

See also:
 - https://hibernate.atlassian.net/browse/HSEARCH-2164

Thanks,
Sanne