What is ClickHouse?

Description: In this lecture you will learn what ClickHouse is.
⏰ 3 minutes | 📊 Level 1 | 🧪 Lab exercises after all lectures

What is ClickHouse?

All right, so let's dive right in. What is ClickHouse? Well, so ClickHouse is a database, it's a database management system. It's actually a SQL database. If you're curious about the name, so when it actually first started getting developed on in 2009, the first use case was a clickstream data warehouse, and so that's where the click and the house come from as the first use case. In 2012, that started to get used in production, and then eventually it got open sourced.

And so as of today, ClickHouse is Apache 2.0 open source, and I certainly don't see that changing. The big thing about ClickHouse, talking about database management systems, is that it's an OLAP database with the emphasis on the A, the analytical processing, as opposed to an OLTP. ClickHouse is not a transactional processing database. In fact, ClickHouse doesn't even have the concept of transactions, at least not yet. It's strictly for analyzing data. And so, yeah, it's SQL, and yeah, you can take your create table command from your Postgres or your Oracle Database and just copy and paste it into ClickHouse, but that's probably not even going to work.

You can do it, but that's probably a bad idea, just from the sense of how your table was designed for the transactional database, and now you're coming into ClickHouse, which is really just a different sort of tool altogether. And you'll see that as we go through the ClickHouse architecture, and you start to understand what the difference is. But just keep that in mind, that it is a different thing. It's a different database. So in 2012, it went into production.

It got open source in 2016. The company, ClickHouse Inc., started in 2021, and I was fortunate to be there at the beginning. In 2022, we released the first version of the cloud. So ClickHouse is still open source, but as a company, we make revenue off of our ClickHouse cloud offering, which is just wonderful. You'll see that right away here in this first module. I'll spin up a cloud instance, kind of show you how it works. And you can see the community, the GitHub stars.

Look, there's a lot of excitement and enthusiasm and really momentum in ClickHouse right now. It's really starting to take off as people realize how nice it is. It's a SQL database. It's column-oriented, and we'll talk about that in module two. It's designed for fast ingestion. Wait till you see some of the numbers that I'm about to show you on how much data you can put into ClickHouse, and not just put the data in, but also be able to query that data.

And like I said, it's not an OLTP. Our queries will often be 1,000, 10,000 times faster than a sort of old school transactional type database. So, all right. So we're going to use it for analytics. It's not a tool that you would use for transactions. You're still going to use your Postgres database, your MongoDB database, your MySQL. You're still going to have those transactional databases. In a lot of cases, we see people syncing or copy, moving the data into ClickHouse to analyze it.

That's a pretty common use case. So it depends on your scenario.