Citus Blog

Articles tagged: scale out

We released Citus 11 in the previous weeks and it is packed. Citus went full open source, so now previously enterprise features like the non-blocking aspect of the shard rebalancer—and multi-user support—are all open source for everyone to enjoy. One other huge change in Citus 11 is now you can query your distributed Postgres tables from any Citus node, by default.

When using Citus to distribute Postgres before Citus 11, the coordinator node was your application’s only point of contact. Your application needed to connect to the coordinator to query your distributed Postgres tables. Coordinator node can handle high query throughput, about 100K per second but your application might need even more processing power. Thanks to our work in Citus 11 you can now query from any node in the Citus database cluster you want. In Citus 11 we sync the metadata to all nodes by default, so you can connect to any node and run queries on your tables.

Running queries from any node is awesome but you also need to be able to monitor and manage your queries from any node. Before, when you only connected the coordinator, using Postgres’ monitoring tools was enough but this is not the case anymore. So in Citus 11 we added some ways to observe your queries similar to you would do in a single Postgres instance.

Keep reading

Citus 11.0 is here! Citus is a PostgreSQL extension that adds distributed database superpowers to PostgreSQL. With Citus, you can create tables that are transparently distributed or replicated across a cluster of PostgreSQL nodes. Citus 11.0 is a new major release, which means that it comes with some very exciting new features that enable new levels of scalability.

The biggest enhancement in Citus 11.0 is that you can now always run distributed queries from any node in the cluster because the schema & metadata are automatically synchronized. We already shared some of the details in the Citus 11.0 beta blog post, but we also have big surprise for those of you who use Citus open source that was not part of the initial beta.

When we do a new Citus release, we usually release 2 versions: The open source version and the enterprise release which includes a few extra features. However, there will be only one version of Citus 11.0, because everything in the Citus extension is now fully open source!

That means that you can now rebalance shards without blocking writes, manage roles across the cluster, isolate tenants to their own shards, and more. All this comes on top of the already massive enhancement in Citus 11.0: You can query your Citus cluster from any node, creating a truly distributed PostgreSQL experience.

Keep reading

One of the big new things in Citus 10 is that you can now shard Postgres on a single Citus node. So in addition to using the Citus extension to Postgres to scale out Postgres across a distributed cluster, you can now also:

  • Try out Citus on a single node with just a few simple commands
  • Shard Postgres on a single Citus node to be “scale-out-ready”
  • Simplify CI/CD pipelines by testing with single-node Citus

The Citus 10 release is chock full of new capabilities like columnar storage for Postgres, the open sourcing of the shard rebalancer, as well as the feature we are going to explore here: using Citus on a single node. No matter what type of application you run on top of Citus—multi-tenant SaaS apps, customer-facing analytics dashboards, time-series workloads, high-throughput transactional apps—there is something for everyone in Citus 10.

Keep reading

One of the main reasons people use the Citus extension for Postgres is to distribute the data in Postgres tables across multiple nodes. Citus does this by splitting the original Postgres table into multiple smaller tables and putting these smaller tables on different nodes. The process of splitting bigger tables into smaller ones is called sharding—and these smaller Postgres tables are called “shards”. Citus then allows you to query the shards as if they were still a single Postgres table.

One of the big changes in Citus 10—in addition to adding columnar storage, and the new ability to shard Postgres on a single Citus node—is that we open sourced the shard rebalancer.

Yes, that’s right, we have open sourced the shard rebalancer! The Citus 10 shard rebalancer gives you an easy way to rebalance shards across your cluster and helps you avoid data hotspots over time. Let’s dig into the what and the how.

Keep reading

GPS has become part of our daily life. GPS is in cars for navigation, in smartphones helping us to find places, and more recently GPS has been helping us to avoid getting infected by COVID-19. Managing and analyzing mobility tracks is the core of my work. My group in Université libre de Bruxelles specializes in mobility data management. We build an open source database system for spatiotemporal trajectories, called MobilityDB. MobilityDB adds support for temporal and spatiotemporal objects to the Postgres database and its spatial extension, PostGIS. If you’re not yet familiar with spatiotemporal trajectories, not to worry, we’ll walk through some movement trajectories for a public transport bus in just a bit.

One of my team’s projects is to develop a distributed version of MobilityDB. This is where we came in touch with the Citus extension to Postgres and the Citus engineering team. This post presents issues and solutions for distributed query processing of movement trajectory data. GPS is the most common source of trajectory data, but the ideas in this post also apply to movement trajectories collected by other location tracking sensors, such as radar systems for aircraft, and AIS systems for sea vessels.

Keep reading

How do you know if the next update to your software is ready for hundreds of millions of customers? It starts with data. And when it comes to Windows, we’re talking lots of data. The Windows team measures the quality of new software builds by scrutinizing 20,000 diagnostic metrics based on data flowing in from 1.2 billion Windows devices. At the same time, the team evaluates feedback from Microsoft engineers who are using pre-release versions of Windows updates.

At Microsoft, the Windows diagnostic metrics are displayed on a real-time analytics dashboard called “Release Quality View” (RQV), which helps the internal “ship-room” team assess the quality of the customer experience before each new Windows update is released. Given the importance of Windows for Microsoft’s customers, the RQV analytics dashboard is a critical tool for Windows engineers, program managers, and execs.

Keep reading
Craig Kerstiens

Options for scaling from 1 to 100,000 tenants

Written byBy Craig Kerstiens | June 28, 2018Jun 28, 2018

When you first start out in building a SaaS application you talk about that day in the future when you will have scaling problems, how that’ll be the day, how that would be a good problem to have. You focus on getting the first few customers, making sure they have a great experience, and suddenly you’re at 10s of customers, then 100s. You’ve upgraded your app server to a larger one, then you’ve gone from one ec2 app server to multiple ones with ELB in front of things. You’ve upgraded your Postgres database from an r3.large on AWS, to r3.xlarge, now you’re eyeing that r3.2xlarge next month. In the back of your mind though, you’re starting to look at your plans for future growth of your SaaS app, and you’re wondering how much larger you can keep going. Your database is performing well at 100 tenants (tenants = customers), your back of the napkin math says you’ll be able to scale your app up to 1,000 tenants, but after that you know you’re going to have to explore some options.

What are those options and what are the trade-offs and benefits?

Keep reading
Craig Kerstiens

Citus what is it good for? OLTP? OLAP? HTAP?

Written byBy Craig Kerstiens | June 7, 2018Jun 7, 2018

Earlier this week as I was waiting to begin a talk at a conference, I chatted with someone in the audience that had a few questions. They led off with this question: is Citus a good fit for X? The heart of what they were looking to figure out: is the Citus distributed database a better fit for analytical (data warehousing) workloads, or for more transactional workloads, to power applications? We hear this question quite a lot, so I thought I’d elaborate more on the use cases that make sense for Citus from a technical perspective.

Before I dig in, if you’re not familiar with Citus; we transform Postgres into a distributed database that allows you to scale your Postgres database horizontally. Under the covers, your data is sharded across multiple nodes, meanwhile things still appear as a single node to your application. By appearing still like a single node database, your application doesn’t need to know about the sharding. We do this as a pure extension to Postgres, which means you get all the power and flexibility that’s included within Postgres such as JSONB, PostGIS, rich indexing, and more.

Keep reading
Craig Kerstiens

Preparing your multi-tenant app for scale

Written byBy Craig Kerstiens | May 22, 2018May 22, 2018

We spend a lot of time with companies that are growing fast, or planning for future growth. It may be you’ve built your product and are now just trying to keep the system growing and scaling to handle new users and revenue. Or you may be still building the product, but know that an even moderate level of success could lead to a lot of scaling. In either case where you spend your time is key in order to not lose valuable time.

As Donald Knuth states it in Computer Programming as an Art:

“Programmers waste enormous amounts of time thinking about, or worrying about, the speed of noncritical parts of their programs, and these attempts at efficiency actually have a strong negative impact when debugging and maintenance are considered. We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. Yet we should not pass up our opportunities in that critical 3%.”

With the above in mind one of the most common questions we get is: What do I need to do now to make sure I can scale my multi-tenant application later?

We’ve written some before about approaches not to take such as schema based sharding or one database per customer and the trade-offs that come with that approach. Here we’ll dig into three key steps you should take that won’t be wasted effort should the need to scale occur.

Keep reading
Craig Kerstiens

Database sharding explained in plain English

Written byBy Craig Kerstiens | January 10, 2018Jan 10, 2018

Sharding is one of those database topics that most developers have a distant understanding of, but the details aren’t always perfectly clear unless you’ve implemented sharding yourself. In building the Citus database (our extension to Postgres that shards the underlying database), we’ve followed a lot of the same principles you’d follow if you were manually sharding Postgres yourself. The main difference of course is that with Citus, we’ve done the heavy lifting to shard Postgres and make it easy to adopt, whereas if you were to shard at the application layer then there’s a good bit of of work needed to re-architect your application.

I’ve found myself explaining how sharding works to many people over the past year and realized it would be useful (and maybe even interesting) to break it down in plain English.

Keep reading

Page 1 of 2