You know, for search

What is Elasticsearch?

Elasticsearch is a tool for querying written words.

Elasticsearch is a near real time search platform.

Terminology

MySQL Elastic Search

Database Index

Table Type

Row Document

Column Field

Schema Mapping

Index Everything is indexed

SQL Query DSL

SELECT * FROM table … GET http://…

UPDATE table SET … PUT http://…

Index Example

Term Count Docs4 1 <3>

Apache 1 <3>

Cookbook 1 <3>

ElasticSearch 2 <1><2>

Mastering 1 <1>

Server 1 <1>

Solr 1 <3>

1. ElasticSearch Server (document 1) 2. Mastering ElasticSearch (document 2) 3. Apache Solr 4 Cookbook (document 3)

Indexing

ElasticSearch is able to achieve fast search responses because, instead of searching the text directly, it searches an index instead.

Cluster

A cluster is a collection of one or more nodes (servers) that together holds your entire data and provides federated indexing and search capabilities across all nodes.

Node

A node is a running instance of Elasticsearch

DocumentMost entities or objects in most applications can be serialized into a JSON object, with keys and values.

{ "name": "John Smith", "age": 42, "confirmed": true, "join_date": "2014-06-01", "home": { "lat": 51.5, "lon": 0.1 }, "accounts": [ { "type": "facebook", "id": "johnsmith" }, { "type": "twitter", "id": "johnsmith" } ]}

Type

Within an index, you can define one or more types. A type is a logical category/partition of your index whose semantics is completely up to you. In general, a type is defined for documents that have a set of common fields.

Index

An index is a collection of documents that have somewhat similar characteristics. For example, you can have an index for customer data, another index for a product catalog, and yet another index for order data.

Shard

• A single Lucene index• Automatically managed by elasticsearch• Distributed amongst all nodes in the cluster

Replica

• A copy of the primary shard• Each primary shard can have zero or more replicas

Workshop

Installing Elasticsearch

• curl -L -O http://download.elasticsearch.org/PATH/TO/LATEST/$VERSION.zip

•unzip elasticsearch-$VERSION.zip

• ./bin/plugin -i elasticsearch/marvel/latest

Running Elasticsearch• Start : ./bin/elasticsearch• Test it out by opening another terminal window and running:• curl 'http://localhost:9200/?pretty‘• {

"status": 200, "name": "Shrunken Bones", "version": { "number": "1.1.0", "lucene_version": "4.7" }, "tagline": "You Know, for Search"}

Talking to Elasticsearch

• Java API• Restful api with json over http

Request• A request to Elasticsearch consists of the same parts as any HTTP request.

For instance, to count the number of documents in the cluster, we could use:

Response

Elasticsearch returns an HTTP status code like 200 OK and (except for HEAD requests) a JSON encoded response body. The above curl request would respond with a JSON body like the following:

Indexing employee documents

Retrieving Document

Search Lite