Introduction to Elasticsearch

Jason Austin - @jason_austin

The Problem

• You are building a website to find beers

• You have a huge database of beers and breweries to sift through

• You want simple keyword-based searching

• You also want structured searching, like finding all beers > 7% ABV

• You want to run some analytics on what beers are in your dataset

Enter Elasticsearch

• Lucene based

• Distributed

• Fast

• RESTful interface

• Document-Based with JSON

Install Elasticsearch

• Download from http://elasticsearch.org

• Requires Java to run

Run Elasticsearch

• From the install directory:

./bin/elasticsearch -d!

!

http://localhost:9200/!

Communicating

• Elasticsearch listens to RESTful HTTP requests

• GET, POST, PUT, DELETE

• CURL works just fine

ES Structure

Relational DB

Databases

Tables

Rows

Columns

Elasticsearch

Indices

Types

Documents

Fields

ES Structure

Elasticsearch

Indices

Types

Documents

Fields

Elasticsearch

phpbeer

beer

Pliny the Elder

ABV, Name, Desc

Create an Indexcurl -XPOST 'http://localhost:9200/phpbeer'

What to Search?

• Define the types of things to search

• Beer

• Brewery - Maybe later

Define a Beer

• Name

• Style

• ABV

• Brewery

‣ Name

‣ City

Beer JSON{ ! "name": "Pliny the Elder", ! "style": "Imperial India Pale Ale", ! "abv": 7.0, ! "brewery": { ! ! "name": "Russian River Brewing Co.", ! ! "city": "Santa Rosa", "state": "California" ! } }

Saving The Beer

curl -XPOST 'http://localhost:9200/phpbeer/beer/1' -d '{ ! "name": "Pliny the Elder", ! "style": "Imperial India Pale Ale", ! "abv": 7.0, ! "brewery": { ! ! "name": "Russian River Brewing Co.", ! ! "city": "Santa Rosa", "state": "California" ! } }'

Getting a beercurl -XGET 'http://localhost:9200/phpbeer/beer/1?pretty'

Updating a Beercurl -XPOST 'http://localhost:9200/phpbeer/beer/1' -d '{ ! "name": "Pliny the Elder", ! "style": "Imperial India Pale Ale", ! "abv": 8.0, ! "brewery": { ! ! "name": "Russian River Brewing Co.", ! ! "city": "Santa Rosa", "state": "California" ! } }'

POST vs PUT

• POST

• No ID - Creates new doc, assigns ID

• With ID - Updates or creates new doc

• PUT

• No ID - Error

• With ID - Updates doc

Delete a Beercurl -XDELETE 'http://localhost:9200/phpbeer/beer/1'

Finally! Searching!curl -XGET 'http://localhost:9200/_search?pretty&q=pliny'

Specific Field Searchingcurl -XGET 'http://localhost:9200/_search?pretty&q=style:pliny'!

curl -XGET 'http://localhost:9200/_search?pretty&q=style:imperial'

Alternate Approach

• Search using DSL (Domain Specific Language)

• JSON in request body

DSL Searchingcurl -XGET 'http://localhost:9200/_search?pretty' -d '{ "query" : { "match" : { "style" : "imperial" } } }'

DSL = Query + Filter

• Query - “How well does the document match”

• Filter - Yes or No question on the field

Query DSL• match

• Used to query across all fields for a string

• match_phrase

• Used to query an exact phrase

• match_all

• Matches all documents

• multi_match

• Runs the same match query on multiple fields

Filter DSL

• term

• Exact match on a field

• range

• Match numbers over a specified range

• exists / missing

• Match based on the existence of a value for a field

More Complex Search

• Find beer whose styles include “Pale Ale” that are less than 7% ABV

Match + Rangecurl -XGET 'http://localhost:9200/_search?pretty' -d '{ "query" : { "match" : { "style" : "pale ale" } }, "filter" : { "range" : { "abv" : { "lt" : 7 } } } }'

Embedded Field Searchcurl -XGET 'http://localhost:9200/_search?pretty' -d '{ "query" : { "match" : { "brewery.state" : "California" } } }'

Highlighting Search Results

Highlighting Search Resultscurl -XGET 'http://localhost:9200/_search?pretty' -d '{ "query" : { "match" : { "style" : "pale ale" } }, "highlight": { "fields" : { "style" : {} } } }'

Aggregations

• Collect analytics on your documents

• 2 main types

• Bucketing

• Produce a set of buckets with documents in them

• Metric

• Compute metrics over a set of documents

Bucketing Aggregations

Metric Aggregations

• How many beers exist of each style?

• What is the average ABV of beers for each style?

• How many beers exist that are brewed in California?

What is the average ABV of beers for each style?

curl -XGET 'http://localhost:9200/_search?pretty' -d '{ "aggs" : { "all_beers" : { "terms" : { "field" : "style" }, "aggs" : { "avg_abv" : { "avg" : { "field" : "abv" } } } } } }'

Mappings

• Define how ES searches

• Completely optional

• Must re-index after defining mapping

Create Index with Mapping

curl -XPOST localhost:9200/phpbeer -d '{ "mappings" : { "beer" : { "_source" : { "enabled" : true }, "properties" : { "style" : { "type" : "string", "index" : "not_analyzed" } } } } }'

curl -XDELETE localhost:9200/phpbeer

What is the average ABV of beers for each style?

curl -XGET 'http://localhost:9200/_search?pretty' -d '{ "aggs" : { "all_beers" : { "terms" : { "field" : "style" }, "aggs" : { "avg_abv" : { "avg" : { "field" : "abv" } } } } } }'

Non-Analyzed Fieldscurl -XGET 'http://localhost:9200/_search?pretty&q=style:imperial'!

curl -XGET 'http://localhost:9200/_search?pretty&q=style:hefeweizen'

Flexibility

• Mixing aggregations, filters and queries all together

• What beers have the word “night” in the name that are between 4 and 6 % ABV, broken down by style.

Elasticsearch and PHP

• Elasticsearch PHP Libhttps://github.com/elasticsearch/elasticsearch-php

• Elasticahttp://elastica.io/

Other Awesome ES Features

• Search analyzers

• Geo-based searching

• Elasticsearch Plugins

• kopf - http://localhost:9200/_plugin/kopf

Questions?

• @jason_austin

• http://www.pintlabs.com

• https://joind.in/10821