416: Multi-Dimensional Numbers

Joël discusses the challenges he encountered while optimizing slow SQL queries in a non-Rails application. Stephanie shares her experience with canary deploys in a Rails upgrade. Together, Stephanie and Joël address a listener's question about replacing the wkhtml2pdf tool, which is no longer maintained. The episode's main topic revolves around the concept of multidimensional numbers and their applications in software development. Joël introduces the idea of treating objects containing multiple numbers as single entities, using the example of 2D points in space to illustrate how custom classes can define mathematical operations like addition and subtraction for complex data types. They explore how this approach can simplify operations on data structures, such as inventories of T-shirt sizes, by treating them as mathematical objects. EXPLAIN ANALYZE visualizer (https://explain.dalibo.com/) Canary in a coal mine (https://en.wikipedia.org/wiki/Sentinel_species#Canaries) Episode 413: Developer Tales of Package Management (https://bikeshed.thoughtbot.com/413) Docs for media-specific CSS (https://developer.mozilla.org/en-US/docs/Web/CSS/@media) Episode 386: Value Objects Revisited: The Tally Edition (https://bikeshed.thoughtbot.com/386) Money gem (https://github.com/RubyMoney/money) Transcript: STEPHANIE: Hello and welcome to another episode of The Bike Shed, a weekly podcast from your friends at thoughtbot about developing great software. I'm Stephanie Minn. JOËL: And I'm Joël Quenneville. And together, we're here to share a bit of what we've learned along the way. STEPHANIE: So, Joël, what's new in your world? JOËL: I've recently been trying to do some performance enhancements to some very slow queries. This isn't a Rails app, so we're sort of combining together a bunch of different scopes. And the way they're composing together is turning out to be really slow. And I've reached for a tool that is just really fun. It's a visualizer for SQL query plans. You can put the SQL keywords in front of a query: 'EXPLAIN ANALYZE,' and it will then output a query plan, sort of how it's going to attempt to do the work. And that might be like, oh, we're going to use this index on this table to join on this other thing, and then we're going to...maybe this is a table that we think we're going to do a sequential scan through and, you know, it builds out a whole thing. It's a big block of text, and it's kind of intimidating to look at. So, there are a few websites out there that will do this. You just paste a query plan in, and they will build you a nice, little visualization, almost like a tree of, like, tasks to be done. Oftentimes, they'll also annotate it with metadata that they pulled from the query plan. So, oh, this particular node is the really expensive one because we're doing a sequential scan of this table that has 15 million rows in it. And so, it's really useful to then sort of pinpoint what are the areas that you could optimize. STEPHANIE: Nice. I have known that you could do that EXPLAIN ANALYZE on a SQL query, but I've never had to do it before. Is this your first time, or is it just your first time using the visualizer? JOËL: I've played around with EXPLAIN ANALYZE a little bit before. Pro tip: In Rails, if you've got a scope, you can just chain dot explain on the end, and instead of running the query, it will run the EXPLAIN version of it and return the query plan. So, you don't need to, like, turn into SQL then manually run it in your database system to get the EXPLAIN. You can just tack a dot explain on there to get the query plan. It's still kind of intimidating, especially if you've got a really complex query that's...this thing might be 50 lines long of EXPLAIN with all this indentation and other stuff. So, putting it into a sort of online visualizer was really helpful for the work that I was doing. So, it was my first time using an online visualizer. There are a few out there. I'll link to the one that I used in the show notes. But I would do that again, would recommend. STEPHANIE: Nice. JOËL: So, Stephanie, what's new in your world? STEPHANIE: So, I actually just stepped away from being in the middle of doing a Rails upgrade [chuckles] and releasing it to production just a few minutes before getting on to record with you on this podcast. And the reason I was able to do that, you know, without feeling like I had to just monitor to see how it was going is because I'm on a project where the client is using canary deploys. And I was so pleasantly surprised by how easy it made this experience where we had decided to send the canary release earlier this morning. And the way that they have it set up is that the canary goes to 10% of traffic. 10% of the users were on Rails 7 for their sessions. And we saw a couple of errors in our error monitoring service. And we are like, "Okay, like, let's take a look at this, see what's going on." And it turns out it was not too big of a deal because it had to do