Elasticsearch is a distributed, RESTful search and analytics engine capable of searching, analyzing, and storing large volumes of data. It allows for flexible configuration via a REST API and JSON documents and is scalable, versatile in search capabilities including text analytics, and open source. Elasticsearch can index data in flexible schemas and supports various data modeling approaches like flat structures with separate indexes or denormalized structures to optimize search performance at the cost of update efficiency.

1. Karel Minařík
@karmiq
elasticsearch

2. What is Elasticsearch?

3. Elasticsearch
Flexible REST API & JSON documents; API
driven configuration; scripting;
index aliases; …
Scalable Distributed; built for cloud; …
Versatile Search; analytics; storage; alerting;
text clustering; NLP …
Open Open source; community; plugins; …

4. Demo
http://git.io/hello-elasticsearch-ruby

5. http://stackoverflow.com
total
title
date author
rating
answers
result ordering
query
syntax
excerpt
highlight

6. http://stackexchange.com/sites?view=list#questions

7. Schema-less is not schema-free

8. Flat structure
An index per model. "Common search" scenario. Cannot cross-search.
users
questions
answers
comments
{
"name" : "John",
"location" : "..."
}
{
"title" : "My First Question",
"body" : "..."
}
{
"title" : "My First Answer",
"body" : "..."
}
{
"body" : "Just a comment: ..."
}

9. Denormalized
Cheap to query, expensive to update.
{
"title": "My first question",
"body": "...",
"user": {
"name": "John",
"location": "..."
},
"comments": [
{
"text": "Good question!",
"user": {
"name": "Robert",
"location": "..."
}
}
]
}
questions
answers

10. Compromised denormalisation
Some properties don't change (user_name). Some can either be "freezed" or we have to pay the price of the mass update (user_location).
{
"id" : "john",
"name" : "John",
"location" : "..."
}
myapp
user
question
answer
{
"id" : 1,
"title" : "My first question",
"body" : "...",
"user" : {
"name" : "John",
"location" : "..."
},
"comments" : [
{ "body" : "...", "user" : { ... } },
{ "body" : "...", "user" : { ... } }
]
}
{
"id" : 2,
"title" : "My first answer",
"parent_id" : 1,
"user" : {
"name" : "Robert",
"location" : "..."
},
"comments" : [
{ "body" : "...", "user" : { ... } }
]
}
parent_id
comment
comment

11. http://git.io/stackexchange-elasticsearch
Demo

12. thanks!