The first difference is the use of a GenServer. Access AWS, fetch values for specific project/env end end This means you can store a group of %Accounts.User end defp get_list_of_enabled_flags () do #. No SerializationĮTS tables can store Elixir data structures. The lookup of an item (or group of items) is optimized depending on the type of the ETS table. Things to Keep in Mind When Using ETS as a Cache Solution Integration of Unnecessary DependenciesĮTS is part of the Erlang VM, so there are no additional dependencies necessary when using it. Although they might not reflect the real number, they indicate a "good enough" number, which is meaningful to customers. We cache those values and update them every couple of minutes. There are several cases where we need to display things like "X people have purchased that plan" or "That product was already used by Y customers".Ī naive approach would be to perform database queries every time such values are required, but that would be extremely heavy (and unnecessary) on our database. We store our feature flags in AWS Parameter Store, fetching them once every 5 minutes and caching them locally in an ETS table. We use continuous delivery at the company I work in, and feature flags are crucial if you're doing trunk-based-development and want to integrate new, albeit not finished code, without enabling it for customers. Here are two examples where I recently used ETS for caching purposes: Feature Flags When compared to linear access times for a list, both cases have better performance. ![]() Depending on the type, the Erlang VM uses either Hash Tables or Binary Trees to represent the ETS table. The data structures used to implement the ETS tables in the Erlang VM are optimized to provide the best possible access time. The best ETS type to use depends on the specific needs of an application. Here's a small example of the usage of an ETS table: It enables developers to store and access data using a key. In Elixir, the need for caching information is common as a way of avoiding the unnecessary hurdle of accessing information that has a high-cost tag attached to it.Įlixir comes with a huge advantage that might help simplify the lives of developers in need of caching-ETS.ĮTS stands for Erlang Term Storage. As simple as it initially seems, the operational costs of keeping that dependency alive (running, monitoring, patching with the latest security updates, etc.), might be overwhelming when the requirements are rather simple. Using these tools is almost a standard practice now.Īlthough that's a valid approach, it introduces yet another dependency to a project. Popular programming languages usually rely on external dependencies such as Memcache or Redis for caching. It has been around for a long time and is a smart concept, ported from real-life situations. In computing, caching is a ubiquitous concept that is used in both hardware and software. That concept of keeping things that are important, but are costly to get, close to the subject that needs to use them, is commonly referred to as caching. To stop playing so as to get another cookie is not something he enjoys, so he started grabbing multiple cookies and keeping them in his hands. He loves them so much that even while playing soccer, he keeps going back to the jar to grab one more. My two-year-old son loves eating cookies. Instead, what I can do is add mix ecto.dump to in an alias around ecto.migrate and ecto.rollback, add structure.sql to my VCS, and add some docs stating that on a fresh setup the schema needs to be loaded before migrations runs.In this post, you'll learn how to use ETS as a caching mechanism in your Elixir applications, get familiar with different available options, and be made aware of some things to keep in mind. So, there’s no real reason for me to need those duplicated migrations since the structure of the database is already to that point. I think I posted without thinking about this enough. If I’m reading the above correctly, I should just mix ecto.dump the structure, remove the migration files that got the DB to that point, and build new migrations on top of that? How does that effect the test suite? While developing the new elixir app I generated ecto migrations that matched the rails app so that my tests would run properly. ![]() I’ve since deployed the elixir app and shut down the rails app. Im in a similar situation, I was building out an elixir app that was using data from a database originally created & migrated by rails.
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