Engineering

Foreign keys are an important element of any relational database. But when you’re setting up your database schema, it’s relatively easy to create problems for yourself if the foreign keys aren’t set up correctly. Here are three of the most common mistakes made with foreign keys, and a little advice on how to avoid them!

Charlie Custer

June 28, 2023

NOT NULL constraints are a ubiquitous tool for upholding data integrity. However, their performance benefits are less obvious. NOT NULL constraints provide a query optimizer with additional context that unlocks optimizations that significantly reduce query latency. In this post we’ll examine a few of these optimizations that transform query plans involving foreign key relationships.

Marcus Gartner

June 27, 2023

During the Winter of 2023, I had the wonderful opportunity to work as a Software Engineering Intern on the SQL Queries team at Cockroach Labs. During the scope of this internship, I found myself working with indexes and specifically implementing forward indexes on columns storing JSONB, which resulted in speeding up query execution time by up to 98% in some cases! This blog post will go over the motivations for the implementation of these indexes, the main challenges that came up with the implementation, and some demonstrations of the staggering results.

In a distributed database, a hotspot is an overworked node – in other words, a part of the database that’s processing a greater share of the total workload than it is meant to handle.

Charlie Custer

June 7, 2023

A foreign key is a column or columns in a database that (e.g. table_1.column_a) that are linked to a column in a different table (table_2.column_b). The existence of a foreign key column establishes a foreign key constraint – a database rule that ensures that a value can be added or updated in column_a only if the same value already exists in column_b.

Charlie Custer

May 4, 2023

In this post we’re going to talk about one of the techniques that can be used in CockroachDB for getting good performance from databases accessed from multiple geographical regions: follower reads. These are operations presenting a slightly stale view of data, which can be served with local latencies from different regions.

I once went to a website that had “hours of operation,” and was only “open” when its brick and mortar counterpart had its lights on. I felt perplexed and a little frustrated; computers are capable of running all day every day, so why shouldn’t they? I’d been habituated to the internet’s incredible availability guarantees. However, before the internet, 24/7 high availability wasn’t “a thing.” Availability was desirable, but not something to which we felt fundamentally entitled. We used computers only when we needed them; they weren’t waiting idly by on the off-chance a request came by. As the internet grew, those previously uncommon requests at 3am local time became prime business hours partway across the globe, and making sure that a computer could facilitate the request was important.

Jessica Edwards

March 23, 2023

JSON is a ubiquitous data interchange format supported by many systems, including CockroachDB. Historically, at CockroachDB, the majority of our efforts around JSON focused on supporting various JSON functions, operators, and inverted indexes while our JSON parser did not receive much attention. And for a good reason. If you are reading this blog, then you probably already appreciate Golang. There are many aspects to like in Go, and one of them is an excellent collection of standard (and third party) libraries. Becase Go ships with a “jack-of-all-trades” JSON parser out of the box (encoding/json library), it made sense for CockroachDB to use a standard parser when converting strings to internal JSON representation. However, at some point, we began to wonder if the time had arrived for us to invest in finding a better, more performant alternative.

*Note: this post originally ran in 2020, at the very beginning of our managed service/multi-tenant engineering journey. If you want an update on what kind of deployment models CockroachDB offers and what our current capabilities are check out our latest release blog. There’s this really fun game I like to play. You get a bunch of SREs in a room and you see how quickly you can rile them up. Here are some things to say next time you’re in a room of SREs:

Josh Imhoff

October 20, 2022