- Previous versions of ElasticSearch advocated concept of rivers
- Rivers would be installed as plug-in into ElasticSearch
- River would pull data automatically from the source database
- Article published by ElasticSearch suggests that rivers are now deprecated
- Some NoSql vendors implemented plug-ins for data population and synchronization e.g.: Couchbase
- Some third parties implemented plug-ins for Cassandra
- Client specific Sdk tend to support bulk api natively: Node.js, Java, Python, and etc.