Apache Druid Review: Real-Time Analytics Database

published on 04 April 2024

Looking for a powerful tool to analyze your data in real-time? Apache Druid might be what you need. Here's a quick overview:

  • Fast Data Analysis: Druid excels at analyzing massive datasets quickly, giving you insights in milliseconds.
  • Real-Time Data Ingestion: It can ingest data as it happens, from sources like Kafka, making it ideal for live data analysis.
  • Scalability: Easily scales to handle more data by adding resources.
  • Flexibility: Works with both real-time and historical data from various sources.
  • Resilience: It's designed to keep running smoothly, even when issues arise.

However, it's not without its drawbacks. Setting it up can be complex, and it may not suit every data management need out there. If quick, real-time data analysis is crucial for your operations, and you're ready to navigate its setup, Druid could be a game-changer for your data strategy.

Origin and Development

Apache Druid was born in 2011 because some smart folks at Metamarkets needed a faster way to look at lots of data in real-time. Before Druid, tools like relational databases or Hadoop were slow and costly for analyzing heaps of user data from websites.

From the get-go, Druid was quick, managing to sort and sift through over 1 billion rows in less than a second. Now, it's a widely used open-source tool for analyzing data, with more than 1,400 organizations using it across different fields.

Key Features and Capabilities

  • Real-time data ingestion - Druid can take in data as it happens, handling millions of bits of information every second from places like Kafka and Kinesis.
  • Scalability - You can add or take away parts as needed without a fuss.
  • High concurrency - It's built to handle a lot of queries at once, quickly.
  • Sub-second query performance - It's really fast, giving you answers in milliseconds, even when dealing with billions of rows.
  • Unified batch + streaming - It can handle data coming in live or data that's already been collected, from various sources.
  • Fault tolerance - It keeps running smoothly, even if there are hiccups or changes in setup.

Architecture Overview

Druid's setup involves different types of nodes, each doing its own thing:

  • Master nodes - They make sure data is where it should be and oversee data coming in.
  • Query nodes - These nodes take your questions (queries) and find the answers.
  • Data nodes - Here, data is brought in and stored in a way that makes it easy to access for queries.

Druid uses a mix of cloud storage like S3 and local disk storage. This way, it benefits from cheaper cloud storage and the speed of local access.

During data ingestion, information is organized into indexed segments. This makes searching faster because you only look through the data you need. Druid also uses smart shortcuts, like pre-aggregation and special algorithms, to deliver fast results, even for huge datasets.

The system is flexible, letting you add or remove nodes as needed, and it's designed to keep running, even if something goes wrong.

Deployment and Use Cases

Typical Deployment Scenarios

Apache Druid is often set up in places where businesses need to look at a lot of data quickly, across different types of work. Here are some common ways it's used:

  • Digital Media/Advertising - Druid helps websites and ad companies quickly handle billions of ad-related activities each day. It makes it easy to sum up data for reports and lets people dig into the data on the spot.
  • Gaming Analytics - Video game companies use Druid to watch how players act, test new ideas, spot cheating, keep an eye on their systems, and make games run better, all in real time.
  • Industrial IoT - Factories use Druid to watch and predict when machines might need fixing, dealing with millions of bits of data from sensors every second.
  • Financial Services - Financial groups use Druid to quickly go through market data for making trading decisions, managing risks, and following rules, where fast responses are key.
  • Web/Mobile Analytics - Big websites and mobile apps use Druid to track how users act. They look at things like how to make personal suggestions, test features, and improve ads.

Druid can work with data that's happening right now and data that's already been gathered, from different places. This makes it a good fit for today's tech setups. Businesses often run Druid on their own computer systems or in the cloud, like with AWS, and can adjust how many resources they're using based on the data they're handling.

Real-World Use Cases

Druid is used for important tasks in many areas:

  • Airbnb - Druid helps spot fake activities on their site by looking at billions of events a day, keeping users safe.
  • Yahoo! Japan - Druid helps Yahoo! Japan suggest personalized things by searching through 3 trillion records every night.
  • Cisco - Cisco uses Druid to watch over its network equipment in real time, spotting problems early and predicting when they might need fixing.
  • PayPal - Druid looks at transaction data as it happens, helping to spot fraud, understand customers better, and improve security.
  • Pandora - Druid uses past data and new info to make better music suggestions and target ads to 76 million users.

These examples show how Druid can be used in different ways, from helping websites and apps understand their users better to keeping big systems running smoothly.

Pros and Cons Analysis

Pros Cons
Quick at taking in and handling live or stored data Basic options for making it secure and managing groups of computers
Can pick and choose important data to save and process It can be hard to fix issues without knowing a lot about how Druid works
Setting up data collection is straightforward
Using cloud storage like S3 can be cheaper than other options
It's fast at answering questions because it organizes data ahead of time
You can tweak how it collects data to make it work better for you

Druid is really good at quickly taking in and handling a lot of data at once, which is great for looking at information as it happens. You can also set it up to only look at the data you think is important, which can save money and time.

Druid is smart in how it gets ready to answer questions. By organizing data in advance, it doesn't have to work as hard later on, which means you get answers faster. Plus, you can change how it collects data depending on what you need, which helps it do its job better.

However, Druid isn't the best when it comes to making your data secure or managing a bunch of computers it runs on, without some extra work. And, if something goes wrong during data collection, it might be tough to figure out what happened if you're not already familiar with how Druid works.

All in all, Druid is really good at what it does, especially for looking at data right when it happens. But you'll need to think about whether its way of doing things fits what you need in terms of security, managing the system, and figuring out problems.

Technical Deep Dive

Data Ingestion and Management

Apache Druid can take in data in two ways: all at once (batch) or bit by bit as it happens (streaming), from places like Kafka, Kinesis, HDFS, S3, and others. You can either use the data as it comes or change it a bit using simple commands or custom rules during the process of bringing it in.

After the data is in Druid, it smartly divides it up, makes copies for safety, and decides where to keep it based on rules you set. This helps your searches go fast and can also cut down on costs by moving old data that you don't look at much to cheaper storage.

If you need to add new kinds of data, Druid lets you do that without stopping anything. And if you need to change how your data is set up, there are tools to help with that too.

Query Performance

Druid is quick at finding what you're looking for because of a few smart tricks:

  • Columnar storage format - It keeps data in columns instead of rows, which means it can read and compress data faster.
  • Segmentation - It breaks data into chunks that are just the right size for searching quickly. These chunks help Druid do many searches at once.
  • Indexes - These are like quick reference guides for data, helping Druid filter through it fast.
  • Approximate algorithms - Druid can guess answers for big picture questions quickly, and you can decide how precise you want these guesses to be.
  • Caching - It keeps frequently looked-at data ready to go, so it doesn't have to fetch it every time.

By using these methods, Druid can do lots of searches at the same time and use smart ways to skip over data it doesn't need, which means you get answers faster.

Security and Management

Druid lets you control who can see what data by setting up roles. You can also use systems like LDAP to check who's trying to access the data. You can set up rules to control how data moves around inside Druid.

Managing a Druid setup is pretty straightforward. It takes care of itself, fixing problems and adjusting as needed. If you're using tools like Kubernetes, Druid fits in nicely. You can also use tools like Prometheus to keep an eye on how well everything is running.

If you don't want to manage Druid yourself, there are services that will do it for you, taking care of all the technical stuff.


Comparative Analysis

Against Other Databases

When we look at Apache Druid next to other databases like PostgreSQL, MongoDB, and ClickHouse, a few things make it really good for working with data that's constantly updating:

Real-Time Data Ingestion

  • Druid can take in data as it happens, like tweets or website clicks, from places like Kafka, and it does this super fast. It can handle loads of data every second without slowing down.
  • Databases like PostgreSQL and MongoDB can't take in data this fast.

Ad-Hoc Analytics

  • Druid is built to quickly look through huge amounts of data and find what you need right away. It stores data in a smart way and sometimes summarizes it ahead of time to make this possible.
  • While looking through billions of rows, it still gives you answers in less than a second.
  • Other databases might take a lot longer to do this kind of search.


  • Druid is made to grow with your data. You can add more computers to it as needed, and it figures out how to manage the data across them all by itself.
  • This is easier to do with Druid than with databases like PostgreSQL and MongoDB, which can be tricky to make bigger.

In simple terms, Druid is really good at taking in lots of data as it comes in, searching through big amounts of data quickly, and growing with your needs. This makes it a great choice for keeping up with data that's always changing.

Industry Benchmarks

Tests comparing Druid to other tools show it's much faster:

  • In a test called TPC-H, Druid was way faster than Presto and Hive, two other tools used for looking at data. It was more than 90% faster than Presto and 98% faster than Hive.
  • In another test with a 100GB set of data, Druid finished queries in less than a second, while Presto took 90 seconds and Hive took 424 seconds.

These tests prove that Druid is much faster at searching through and analyzing big sets of data compared to some other options out there. It's especially good for when you have a lot of data and need answers fast.


Apache Druid is a smart tool that helps businesses understand and use their data as it comes in. It's really good at dealing with a lot of information quickly, which is great for companies that need to make fast decisions based on fresh data.

Here are some main points about Druid:

  • Real-time data ingestion - Druid can quickly take in data as it happens from sources like Kafka and Kinesis. This means you can look at and use your data almost instantly.
  • Scalability - Druid can grow with your needs. You can add more parts to it to handle more data without a big hassle.
  • Speed - Thanks to smart storage and searching methods, Druid can find the information you need really fast, even if you have tons of data.
  • Handling both new and old data - Druid can work with both the latest data and data you've collected over time. This helps you see the big picture.
  • Stays up and running - Druid is built to keep going even if there are problems, so you can rely on it for important tasks.

However, Druid isn't perfect. It can be tricky to set up and manage, and it might not be the best choice for every single need. But, for companies that need to understand their data in real time, it's a very useful tool.

With the right know-how, you can make Druid work really well for your specific needs. That's where having the right team comes in. Having experts who know how to set up and use Druid can make a big difference.

In short, Druid gives businesses a strong way to make sense of a lot of data quickly. This can help them stay ahead in today's fast-moving world. Being able to act quickly and smartly based on the latest data can set a company apart from the competition.

What are the disadvantages of Apache Druid?

Apache Druid has some limitations:

  • It can't update existing data in real time.
  • It's not great at adding new data quickly.
  • Its search and indexing features are pretty basic.
  • It doesn't have built-in support for different levels of cloud storage.

This means if you need to change data as it comes in, want more advanced search tools, or plan to use cloud storage smartly, Druid might not be the best fit.

Is Apache Druid good?

Druid is really good for certain things:

  • It can handle a lot of data coming in fast.
  • It's quick at summarizing data for things like group searches.
  • It's great for looking at the latest data right away.

So, if you have a lot of data coming in and you want to analyze it on the fly, Druid is a solid choice.

Is Apache Druid a database?

Yes, Apache Druid is a type of database that's all about analyzing data. It's designed to make data queries on big datasets really fast. It's not the same as a regular database that stores all kinds of data, but it's perfect for when you need quick insights from a lot of data.

Is Druid a Nosql database?

Yes, Apache Druid is a NoSQL database. This means it doesn't use the traditional table-based structure to store data. Instead, it's built for analyzing large amounts of data quickly. Over 1,600 companies around the world use Druid for real-time data analysis on a big scale.

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