This document provides an introduction and overview of Elasticsearch. It discusses installing Elasticsearch and configuring it through the elasticsearch.yml file. It describes tools like Marvel and Sense that can be used for monitoring Elasticsearch. Key terms used in Elasticsearch like nodes, clusters, indices, and documents are explained. The document outlines how to index and retrieve data from Elasticsearch through its RESTful API using either search lite queries or the query DSL.

1. Elasticsearch
(Presentation 01)
By
Maruf Hassan
Email: maruf571@gmail.com

2. Contents
● Introduction
● Installation
● Configuration
● Tools(plugin)
● Terms used in Elasticsearch
● Talking with Elasticsearch
● Indexing data
● Retrieving data

3. Introduction
What is Elasticsearch?
● Elasticsearch is an open-source search engine
● Elasticsearch is written in Java
● Built on top of Apache Lucene™
● A distributed real-time document store where
every field is indexed and searchable
● A distributed search engine with real-time
analytics

4. Installation
Setup
● Download zip file for elasticsearch web site
(https://www.elastic.co/downloads/elasticsearch)
● Unzip it anywhere in you pc
Run
● Go to unzip directory & run the following command
./bin/elasticsearch
Test
● To test installation hit on browser @ http://localhost:9200/?pretty or
curl 'http://localhost:9200/?pretty'
“You Know, for Search” Yahoo! everything is file :)

5. Configuration
● elasticsearch.yml file is the main configuration
file in the config directory
● Need restart Elasticsearch to perform update
configuration(if you edit elasticsearch.yml )

6. Tools(plugin)
Installation
● Marvel (plugin) is a monitoring tools, to install
./bin/plugin -i elasticsearch/marvel/latest
● Sense is interactive console inside Marvel.(I like it very much)
● Elasticsearch-head is a document browser, to install
./bin/plugin -install mobz/elasticsearch-head
Run
● To run marvel hit brouwser @ http://localhost:9200/_plugin/marvel/
● To run sence hit brouwser @ http://localhost:9200/_plugin/marvel/sense/
● To run head hit brouwser @ http://localhost:9200/_plugin/head/

7. Terms used in Elasticsearch
● node: running instance of Elasticsearch
● cluster: group of nodes with the same cluster
name
● elasticsearch = relational DB
● indices = databases
● types = tables
● documents = rows

8. Terms used in Elasticsearch
● fields = columns
● index (noun) = like a database in a traditional relational
database
● Index (verb) = to index a document is to store a document
in an index (noun)
● Inverted index = relational databases add an index, such
as a B-tree index, to specific columns in order to improve
the speed of data retrieval. Elasticsearch and Lucene use
a structure called an inverted index for exactly the same
purpose.

9. Talking to Elasticsearch
Two way for java. Node client & Transport client
1. Node client: Work as a node in local cluster, but don’t hold any data
2. Transport client: Send request to remote cluster, don’t join
One way for all
● RESTful API with JSON over HTTP
Port
● Both Java clients talk to the cluster over port 9300
● All other languages can communicate with Elasticsearch over port 9200
using RESTful API

10. Indexing data
● PUT verb used for indexing(inserting data)
●
URL path contains three pieces of information
index_name/type_name/id_of_document
● PUT body contain the document as a json
Example:
PUT /cefalo/employee/1
{
"first_name" : "Maruf",
"last_name" : "Hassan",
"age" : 28,
"about" : "Happy to help",
"interests": [ "science", "music", "internet" ]
}

11. Retrieve data
Two way to retrieve data from Elasticsearch. Search Lite & Query DSL
Search Lite
● allows us to build ad hoc searches
● parameters to be passed in the query string
● Used only for test environment
Query DSL
● allows us to build much more complicated, robust queries
● expects a JSON request body and uses a rich search language called the
query DSL
● Used for production environment

12. Retrieve data(Search Lite)
● Search for all employees in the index cefalo
GET /cefalo/employee/_search
● searching for employees with their last name in
cefalo index
GET /cefalo/employee/_search?
q=last_name:hassan

13. Retrieve data(Query DSL)
● Search for all employees in the cefalo index
GET /cefalo/employee/_search{
}
● Searching for employees with their last name in the cefalo index
GET /cefalo/employee/_search
{
"query" : {
"match" : {
"last_name" : "Hassan"
}
}
}

14. Thanks
&