They also have Alert queries, which are similar to ElasticSearch percolation feature.
MarkLogic is also an ACID compliant store with configurable HA, as well as asynch replication to a remote site. it could potentially serve if correctly configured, as the primary store.
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ArangoDB might have these capabilities as well. And again, it is an ACID compliant database so the data committed, the indices, and the resulting searches should respect transactional boundaries at any moment of time.
I had not looked at ArangoDB deep enough to understand what limitations it might have though. It does not have similarity search capability, and hierarchical data like ElasticSearch has
https://docs.arangodb.com/2.3/IndexHandling/Fulltext.html
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I checked RethinkDB, and it appears that it suggests to integrate with ElasticSearch, meaning that elastic search will have a copy of the data from Rethink (and therefore subject to commit protocol of ElasticSearch)
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Somebody already mentioned Riak with search capability.
I think this one is much more similar to Marklogic's capability (and it is free)
The advantage of these types of systems is that your primary store and text indexes are sitting on top of the single copy of data (or replicated invisibly within the infrastructure)
http://docs.basho.com/riak/latest/dev/using/search/
https://developer.marklogic.com/learn/2009-07-search-api-wal...
They also have Alert queries, which are similar to ElasticSearch percolation feature.
MarkLogic is also an ACID compliant store with configurable HA, as well as asynch replication to a remote site. it could potentially serve if correctly configured, as the primary store.
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ArangoDB might have these capabilities as well. And again, it is an ACID compliant database so the data committed, the indices, and the resulting searches should respect transactional boundaries at any moment of time. I had not looked at ArangoDB deep enough to understand what limitations it might have though. It does not have similarity search capability, and hierarchical data like ElasticSearch has https://docs.arangodb.com/2.3/IndexHandling/Fulltext.html ----
I checked RethinkDB, and it appears that it suggests to integrate with ElasticSearch, meaning that elastic search will have a copy of the data from Rethink (and therefore subject to commit protocol of ElasticSearch)
--- Somebody already mentioned Riak with search capability. I think this one is much more similar to Marklogic's capability (and it is free) The advantage of these types of systems is that your primary store and text indexes are sitting on top of the single copy of data (or replicated invisibly within the infrastructure) http://docs.basho.com/riak/latest/dev/using/search/