feat: New Redix and Caches lessons, refreshed existing storage lessons. by doomspork · Pull Request #3056 · elixirschool/elixirschool

doomspork · 2025-07-13T17:39:10Z

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brain-geek

This is a massive and awesome update.

Added a few notes that might improve readability/consistency.

lessons/en/storage/cachex.md

brain-geek · 2025-11-27T15:46:06Z

lessons/en/storage/cachex.md

+
+## Transactions
+
+Transactions provide atomic operations across multiple keys:


Is it different from Cachex.execute!?

I re-wrote this a bit. Let me know if it's clearer.

brain-geek · 2025-11-27T15:51:48Z

lessons/en/storage/ets.md

+
+### Read Concurrency
+
+For tables with many concurrent readers, enable read concurrency:


Can we have both write and read concurrency? It's not obvious if they are mutually exclusive.

lessons/en/storage/ets.md

brain-geek · 2025-11-27T16:16:19Z

lessons/en/storage/redix.md

+
+### Building a Connection Pool
+
+For high-traffic applications, we might want to use multiple Redis connections. Here's a simple connection pool implementation:


Should we maybe skip this section? High-traffic applications are definitely out of scope for basic technology lesson.

I'm also thinking of removing the pub/sub section now too. I got carried away and wanted to cover too much to be comprehensive

brain-geek · 2025-11-27T16:21:44Z

lessons/en/storage/redix.md

+# Clean up Redis before each test
+ExUnit.after_suite(fn _results ->
+  {:ok, conn} = Redix.start_link(Application.get_env(:my_app, :redis_url))
+  Redix.command!(conn, ["FLUSHDB"])


This will create weird concurrency test failures if you use it in async: true tests.

Also, ExUnit.after_suite runs it after full suite, not each test.

That's fair, let me think about how to capture this best without going to off into the weeds.

brain-geek · 2025-11-27T16:22:47Z

lessons/en/storage/redix.md

+In our `config/test.exs`:
+
+```elixir
+config :my_app, :redis_url, "redis://localhost:6379/15"  # Use a test database


This is the first time we're using redis_url config variable.

Maybe use it in initial supervision tree setup example as well, instead of hardcoding the address?

Good feedback!

brain-geek · 2025-11-27T16:25:47Z

lessons/en/storage/redix.md

+
+Performance optimization comes through strategic use of pipelining when executing multiple commands, which significantly reduces round-trip time compared to individual command execution. Monitoring this performance through telemetry allows us to track command execution times and overall connection health, helping identify issues before they impact users.
+
+Data management practices are equally important: use consistent key naming patterns to avoid conflicts and simplify debugging, and always set appropriate TTLs on cached data to prevent memory bloat and ensure data freshness. For operations requiring atomicity across multiple commands, Redis transactions using MULTI/EXEC provide the necessary guarantees to maintain data consistency.


MULTI hasn't been mentioned once in lesson. My guess you're taking about Redix.pipeline! in this case.

brain-geek · 2025-11-27T16:29:21Z

lessons/en/storage/mnesia.md

-In this case, we are passing in the node associated with our IEx session.
-
-## Nodes
+This command creates a new schema on the current node. After running this, you'll notice a new directory in your current working directory named something like `Mnesia.nonode@nohost` - this is where Mnesia stores its data files.


what is schema?

Co-authored-by: Oleksandr Rozumii <[email protected]>

doomspork · 2025-11-28T15:32:48Z

@brain-geek thank you, thank you! I've been slowly chipping away at these lessons locally as I get back into the flow of writing lessons and explore some potential changes. Let me work through your feedback and other changes, then I'll tag you for another look 😁

I also screwed up using 1 PR for all the lessons, I wasn't anticipating getting reviews but I love it 🫶

doomspork force-pushed the feat-redix-lesson branch from a671023 to 8bed803 Compare July 13, 2025 17:59

doomspork changed the title ~~feat: New Redix lesson~~ feat: New Redix and Caches lessons, refreshed existing storage lessons. Jul 13, 2025

doomspork force-pushed the feat-redix-lesson branch from 8bed803 to 968cee3 Compare July 13, 2025 18:04

doomspork mentioned this pull request Jul 13, 2025

feat: Update lesson listing elixirschool/school_house#234

Closed

doomspork force-pushed the feat-redix-lesson branch 2 times, most recently from e7a2e00 to e4ced0f Compare August 4, 2025 17:32

brain-geek previously approved these changes Nov 27, 2025

View reviewed changes

doomspork dismissed brain-geek’s stale review via dd19a0f November 27, 2025 17:06

doomspork and others added 7 commits November 27, 2025 20:25

feat: New Redix lesson

f9a84c5

feat: New Cachex lesson

b85cd9f

feat: Refresh ETS lesson

6626e91

refactor: Iterate on Storage lessons

cc50e24

refactor: Incorporate feedback

1adfbde

Co-authored-by: Oleksandr Rozumii <[email protected]>

refactor: Continue lesson iteration

f0f3841

refactor: Incorporate Cachex feedback

a6b9051

doomspork force-pushed the feat-redix-lesson branch from e418813 to a6b9051 Compare November 28, 2025 01:26


		## Transactions

		Transactions provide atomic operations across multiple keys:


		### Read Concurrency

		For tables with many concurrent readers, enable read concurrency:


		### Building a Connection Pool

		For high-traffic applications, we might want to use multiple Redis connections. Here's a simple connection pool implementation:


		Performance optimization comes through strategic use of pipelining when executing multiple commands, which significantly reduces round-trip time compared to individual command execution. Monitoring this performance through telemetry allows us to track command execution times and overall connection health, helping identify issues before they impact users.

		Data management practices are equally important: use consistent key naming patterns to avoid conflicts and simplify debugging, and always set appropriate TTLs on cached data to prevent memory bloat and ensure data freshness. For operations requiring atomicity across multiple commands, Redis transactions using MULTI/EXEC provide the necessary guarantees to maintain data consistency.

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doomspork commented Jul 13, 2025

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doomspork commented Nov 28, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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doomspork commented Nov 28, 2025 •

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