Search icon CANCEL
Subscription
0
Cart icon
Your Cart (0 item)
Close icon
You have no products in your basket yet
Arrow left icon
Explore Products
Best Sellers
New Releases
Books
Videos
Audiobooks
Learning Hub
Newsletter Hub
Free Learning
Arrow right icon
timer SALE ENDS IN
0 Days
:
00 Hours
:
00 Minutes
:
00 Seconds
Mastering Elasticsearch 5.x
Mastering Elasticsearch 5.x

Mastering Elasticsearch 5.x: Master the intricacies of Elasticsearch 5 and use it to create flexible and scalable search solutions , Third Edition

eBook
€22.99 €32.99
Paperback
€41.99
Subscription
Free Trial
Renews at €18.99p/m

What do you get with a Packt Subscription?

Free for first 7 days. $19.99 p/m after that. Cancel any time!
Product feature icon Unlimited ad-free access to the largest independent learning library in tech. Access this title and thousands more!
Product feature icon 50+ new titles added per month, including many first-to-market concepts and exclusive early access to books as they are being written.
Product feature icon Innovative learning tools, including AI book assistants, code context explainers, and text-to-speech.
Product feature icon Thousands of reference materials covering every tech concept you need to stay up to date.
Subscribe now
View plans & pricing
Table of content icon View table of contents Preview book icon Preview Book

Mastering Elasticsearch 5.x

Chapter 2. The Improved Query DSL

In the previous chapter, we looked at the overview of Lucene, how it works, how analysis processing is done, and how to use the Apache Lucene query language. In addition to that, we discussed the basic concepts of Elasticsearch. We also introduced Elasticsearch 5.x and covered the latest features introduced in version 2.x as well as 5.x. We also talked about the most important changes/removals of features Elasticsearch has gone through during the transition from 1.x to 5.x. In this chapter, we will dive deep into Elasticsearch, focusing on the Query DSL. We will first go through Lucene similarity algorithm formulas before turning to advanced queries. By the end of this chapter, we will have covered the following topics:

  • The changed default text scoring in Lucene: BM25
  • Understanding precision and recall
  • How BM25 differs from TF-IDF
  • Elasticsearch Query DSL
  • Understanding bool query syntax
  • Which query you should use for your particular use case
  • Important...

The changed default text scoring in Lucene - BM25

Scoring is the most important part of Apache Lucene. It is the process of calculating the score property of a document in a scope of a given query. A score is a factor that describes how well the document matches the query. For score calculation, Lucene supports many algorithms, but since the beginning of Lucene, TF-IDF (term frequency-inverse document frequency) has been the default scoring algorithm. With the release of Apache Lucene 6.0, one of the major changes in Lucene is the changed default scoring algorithm. The default algorithm is now BM25 (Best Matching). In this section, we will also cover two fundamental concepts of search relevancy: precision and recall, and after that, we'll look at the new default Apache Lucene scoring mechanism and how it differs from TF-IDF.

Precision versus recall

After executing a search query, an obvious question comes to mind: Have I found the most relevant documents or am I missing important...

Re-factored Query DSL

The release of Elasticsearch 2.0.0 saw a major refactoring in Elasticsearch Query DSL, the interface provided by Elasticsearch to write queries in the JSON format. Covering complete Query DSL is out of the scope of this book. But for a person who doesn't have much prior experience with a full text search engine, the number of queries exposed by Elasticsearch can be overwhelming and very confusing. So, we have decided to cover the most frequently used queries, along with making readers aware about how to use queries and filters with revised Query DSL syntax. Thus, this book can serve the purposes of both types of readers: those who are aware of old versions as well as those who are starting with version 5.0.

Choosing the right query for the job

In this section, we will start with different categories of queries available in Elasticsearch, looking at which query to use in which situation.

Query categorization

Of course, categorizing queries is a hard task and the following list of categories is not the only correct one. If you were to ask other Elasticsearch users, they would provide their own categories, or say that each query can be assigned to more than a single category, and they would be right. We also think that there is no single way of categorizing the queries; however, in our opinion, each Elasticsearch query can be assigned to one (or more) of the following categories:

  • Basic queries: A category that groups queries allowing searching for a part of the index, either in an analyzed or a non-analyzed manner. The key point in this category is that you can nest queries inside a basic query. An example of a basic query is the term query.
  • Compound queries: A category grouping queries that allows...

Query rewrite explained

We have already talked about scoring, which is valuable knowledge, especially when trying to improve the relevance of our queries. We also think that when debugging your queries, it is valuable to know how all the queries are executed; therefore, it is because of this that we decided to include this section on how query rewrite works in Elasticsearch, why it is used, and how to control it.

If you have ever used queries, such as the prefix query and the wildcard query, basically any query that is said to be multiterm, you've probably heard about query rewriting. Elasticsearch does that because of performance reasons. The rewrite process is about changing the original, expensive query to a set of queries that are far less expensive from Lucene's point of view, and thus speed up the query execution. The rewrite process is not visible to the client, but it is good to know that we can alter the rewrite process behavior. For example, let's look at what Elasticsearch...

The changed default text scoring in Lucene - BM25


Scoring is the most important part of Apache Lucene. It is the process of calculating the score property of a document in a scope of a given query. A score is a factor that describes how well the document matches the query. For score calculation, Lucene supports many algorithms, but since the beginning of Lucene, TF-IDF (term frequency-inverse document frequency) has been the default scoring algorithm. With the release of Apache Lucene 6.0, one of the major changes in Lucene is the changed default scoring algorithm. The default algorithm is now BM25 (Best Matching). In this section, we will also cover two fundamental concepts of search relevancy: precision and recall, and after that, we'll look at the new default Apache Lucene scoring mechanism and how it differs from TF-IDF.

Precision versus recall

After executing a search query, an obvious question comes to mind: Have I found the most relevant documents or am I missing important documents...

Re-factored Query DSL


The release of Elasticsearch 2.0.0 saw a major refactoring in Elasticsearch Query DSL, the interface provided by Elasticsearch to write queries in the JSON format. Covering complete Query DSL is out of the scope of this book. But for a person who doesn't have much prior experience with a full text search engine, the number of queries exposed by Elasticsearch can be overwhelming and very confusing. So, we have decided to cover the most frequently used queries, along with making readers aware about how to use queries and filters with revised Query DSL syntax. Thus, this book can serve the purposes of both types of readers: those who are aware of old versions as well as those who are starting with version 5.0.

Left arrow icon Right arrow icon

Key benefits

  • Master the searching, indexing, and aggregation features in ElasticSearch
  • Improve users’ search experience with Elasticsearch’s functionalities and develop your own Elasticsearch plugins
  • A comprehensive, step-by-step guide to master the intricacies of ElasticSearch with ease

Description

Elasticsearch is a modern, fast, distributed, scalable, fault tolerant, and open source search and analytics engine. Elasticsearch leverages the capabilities of Apache Lucene, and provides a new level of control over how you can index and search even huge sets of data. This book will give you a brief recap of the basics and also introduce you to the new features of Elasticsearch 5. We will guide you through the intermediate and advanced functionalities of Elasticsearch, such as querying, indexing, searching, and modifying data. We’ll also explore advanced concepts, including aggregation, index control, sharding, replication, and clustering. We’ll show you the modules of monitoring and administration available in Elasticsearch, and will also cover backup and recovery. You will get an understanding of how you can scale your Elasticsearch cluster to contextualize it and improve its performance. We’ll also show you how you can create your own analysis plugin in Elasticsearch. By the end of the book, you will have all the knowledge necessary to master Elasticsearch and put it to efficient use.

Who is this book for?

If you have some prior working experience with Elasticsearch and want to take your knowledge to the next level, this book will be the perfect resource for you.If you are a developer who wants to implement scalable search solutions with Elasticsearch, this book will also help you. Some basic knowledge of the query DSL and data indexing is required to make the best use of this book.

What you will learn

  • Understand Apache Lucene and Elasticsearch 5's design and architecture
  • Use and configure the new and improved default text scoring mechanism in Apache Lucene 6
  • Know how to overcome the pitfalls while handling relational data in Elasticsearch
  • Learn about choosing the right queries according to the use cases and master the scripting module including new default scripting language, painlessly
  • Explore the right way of scaling production clusters to improve the performance of Elasticsearch
  • Master the searching, indexing, and aggregation features in Elasticsearch
  • Develop your own Elasticsearch plugins to extend the functionalities of Elasticsearch

Product Details

Country selected
Publication date, Length, Edition, Language, ISBN-13
Publication date : Feb 21, 2017
Length: 428 pages
Edition : 3rd
Language : English
ISBN-13 : 9781786460189
Vendor :
Elastic
Category :
Languages :

What do you get with a Packt Subscription?

Free for first 7 days. $19.99 p/m after that. Cancel any time!
Product feature icon Unlimited ad-free access to the largest independent learning library in tech. Access this title and thousands more!
Product feature icon 50+ new titles added per month, including many first-to-market concepts and exclusive early access to books as they are being written.
Product feature icon Innovative learning tools, including AI book assistants, code context explainers, and text-to-speech.
Product feature icon Thousands of reference materials covering every tech concept you need to stay up to date.
Subscribe now
View plans & pricing

Product Details

Publication date : Feb 21, 2017
Length: 428 pages
Edition : 3rd
Language : English
ISBN-13 : 9781786460189
Vendor :
Elastic
Category :
Languages :

Packt Subscriptions

See our plans and pricing
Modal Close icon
€18.99 billed monthly
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Simple pricing, no contract
€189.99 billed annually
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Choose a DRM-free eBook or Video every month to keep
Feature tick icon PLUS own as many other DRM-free eBooks or Videos as you like for just €5 each
Feature tick icon Exclusive print discounts
€264.99 billed in 18 months
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Choose a DRM-free eBook or Video every month to keep
Feature tick icon PLUS own as many other DRM-free eBooks or Videos as you like for just €5 each
Feature tick icon Exclusive print discounts

Frequently bought together


Stars icon
Total 120.97
Elasticsearch 5.x Cookbook
€45.99
Learning Kibana 5.0
€32.99
Mastering Elasticsearch 5.x
€41.99
Total 120.97 Stars icon

Table of Contents

12 Chapters
1. Revisiting Elasticsearch and the Changes Chevron down icon Chevron up icon
2. The Improved Query DSL Chevron down icon Chevron up icon
3. Beyond Full Text Search Chevron down icon Chevron up icon
4. Data Modeling and Analytics Chevron down icon Chevron up icon
5. Improving the User Search Experience Chevron down icon Chevron up icon
6. The Index Distribution Architecture Chevron down icon Chevron up icon
7. Low-Level Index Control Chevron down icon Chevron up icon
8. Elasticsearch Administration Chevron down icon Chevron up icon
9. Data Transformation and Federated Search Chevron down icon Chevron up icon
10. Improving Performance Chevron down icon Chevron up icon
11. Developing Elasticsearch Plugins Chevron down icon Chevron up icon
12. Introducing Elastic Stack 5.0 Chevron down icon Chevron up icon

Customer reviews

Rating distribution
Full star icon Empty star icon Empty star icon Empty star icon Empty star icon 1
(1 Ratings)
5 star 0%
4 star 0%
3 star 0%
2 star 0%
1 star 100%
Michael Bell Jun 03, 2017
Full star icon Empty star icon Empty star icon Empty star icon Empty star icon 1
Poorly written. Basically it's a regurgitation of the online docs with little attempt to explain the implications of your query and indexing optionsVery disappointing
Amazon Verified review Amazon
Get free access to Packt library with over 7500+ books and video courses for 7 days!
Start Free Trial

FAQs

What is included in a Packt subscription? Chevron down icon Chevron up icon

A subscription provides you with full access to view all Packt and licnesed content online, this includes exclusive access to Early Access titles. Depending on the tier chosen you can also earn credits and discounts to use for owning content

How can I cancel my subscription? Chevron down icon Chevron up icon

To cancel your subscription with us simply go to the account page - found in the top right of the page or at https://subscription.packtpub.com/my-account/subscription - From here you will see the ‘cancel subscription’ button in the grey box with your subscription information in.

What are credits? Chevron down icon Chevron up icon

Credits can be earned from reading 40 section of any title within the payment cycle - a month starting from the day of subscription payment. You also earn a Credit every month if you subscribe to our annual or 18 month plans. Credits can be used to buy books DRM free, the same way that you would pay for a book. Your credits can be found in the subscription homepage - subscription.packtpub.com - clicking on ‘the my’ library dropdown and selecting ‘credits’.

What happens if an Early Access Course is cancelled? Chevron down icon Chevron up icon

Projects are rarely cancelled, but sometimes it's unavoidable. If an Early Access course is cancelled or excessively delayed, you can exchange your purchase for another course. For further details, please contact us here.

Where can I send feedback about an Early Access title? Chevron down icon Chevron up icon

If you have any feedback about the product you're reading, or Early Access in general, then please fill out a contact form here and we'll make sure the feedback gets to the right team. 

Can I download the code files for Early Access titles? Chevron down icon Chevron up icon

We try to ensure that all books in Early Access have code available to use, download, and fork on GitHub. This helps us be more agile in the development of the book, and helps keep the often changing code base of new versions and new technologies as up to date as possible. Unfortunately, however, there will be rare cases when it is not possible for us to have downloadable code samples available until publication.

When we publish the book, the code files will also be available to download from the Packt website.

How accurate is the publication date? Chevron down icon Chevron up icon

The publication date is as accurate as we can be at any point in the project. Unfortunately, delays can happen. Often those delays are out of our control, such as changes to the technology code base or delays in the tech release. We do our best to give you an accurate estimate of the publication date at any given time, and as more chapters are delivered, the more accurate the delivery date will become.

How will I know when new chapters are ready? Chevron down icon Chevron up icon

We'll let you know every time there has been an update to a course that you've bought in Early Access. You'll get an email to let you know there has been a new chapter, or a change to a previous chapter. The new chapters are automatically added to your account, so you can also check back there any time you're ready and download or read them online.

I am a Packt subscriber, do I get Early Access? Chevron down icon Chevron up icon

Yes, all Early Access content is fully available through your subscription. You will need to have a paid for or active trial subscription in order to access all titles.

How is Early Access delivered? Chevron down icon Chevron up icon

Early Access is currently only available as a PDF or through our online reader. As we make changes or add new chapters, the files in your Packt account will be updated so you can download them again or view them online immediately.

How do I buy Early Access content? Chevron down icon Chevron up icon

Early Access is a way of us getting our content to you quicker, but the method of buying the Early Access course is still the same. Just find the course you want to buy, go through the check-out steps, and you’ll get a confirmation email from us with information and a link to the relevant Early Access courses.

What is Early Access? Chevron down icon Chevron up icon

Keeping up to date with the latest technology is difficult; new versions, new frameworks, new techniques. This feature gives you a head-start to our content, as it's being created. With Early Access you'll receive each chapter as it's written, and get regular updates throughout the product's development, as well as the final course as soon as it's ready.We created Early Access as a means of giving you the information you need, as soon as it's available. As we go through the process of developing a course, 99% of it can be ready but we can't publish until that last 1% falls in to place. Early Access helps to unlock the potential of our content early, to help you start your learning when you need it most. You not only get access to every chapter as it's delivered, edited, and updated, but you'll also get the finalized, DRM-free product to download in any format you want when it's published. As a member of Packt, you'll also be eligible for our exclusive offers, including a free course every day, and discounts on new and popular titles.