Elasticsearch basic(ELK -> {Elasticsearch,Logstash,Kibana})

Elasticsearch: JSON document
Elasticsearch is a highly scalable open-source full-text search and analytics engine.
It allows you to store, search, and analyze big volumes of data quickly and in near real time.
It is generally used as the underlying engine/technology that powers applications that have
complex search features and requirements.
Elasticsearch API:
-:Document API
-:Search API
-:Indices API
-:Cat API
-:Cluster API

Single documents API or Multi document APIs

Single Documents API:
-: Index API(Create)
-: Get API
-: Delete API
-: Update API
Multi document APIs:
-: Multi get API
-: Bulk API
-: Delete by query API
-: Update by query API
-: Re-index API(copy data from one index to another index as back-up)
Elasticsearch to database mapping:
-: _index == Database
-:_type == Table
-:_id == primary key