Elasticsearch(Presentation 01)

By Maruf Hassan

Email: maruf571@gmail.com

Contents

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

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

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 :)

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 )

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/

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

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.

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

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" ]

}

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

Retrieve data(Search Lite)

● Search for all employees in the index cefaloGET /cefalo/employee/_search

● searching for employees with their last name in cefalo indexGET /cefalo/employee/_search?q=last_name:hassan

Retrieve data(Query DSL)

● Search for all employees in the cefalo indexGET /cefalo/employee/_search{

}

● Searching for employees with their last name in the cefalo indexGET /cefalo/employee/_search

{

"query" : {

"match" : {

"last_name" : "Hassan"

}

}

}

Thanks

&