>Be client
>Have an issue with incredibly slow webpage load time
>Blame memcache issues

So... I look into the problem. Yes, the page either loads up fast, or times out. So, into the logs I go. Webserver is fine (except the timeout), PHP though... Error log is fine (just notices), but slow log shows the issue is the database (of course... its always the database... ugh)

So, checking the database, there is one ugly query that seems to be an issue. 5 joins and a huge where condition.

So I run EXPLAIN on the query and... Proceed to bang my head against the wall.

OF COURSE ITS SLOW YOU FU******, NONE OF YOUR TABLES HAVE ANY INDEXES.

What do they expect when the database has to always go down the whole table and do everything in memory, until it runs out and has to dump it all on disk and work with it there.

Ugh... Some clients...

Okay, so...

We have backend app written in phalcon 3.4.

I got task to prepare new test enviroment, based on ubuntu 20.04, php 7.4 and 'copy-paste' our Phalcon backend there.

Soooo.. That backend was outsourced and I have exacly 0 Phalcon expirience.

Phalcon 3.4 does not support php 7.4

Last 2 days Im tearing my hair out to port it over to Phalcon 4, with honorable mention why the fuck memcache didnt just want to work, and finally its working.

Now Im taking the heat that making new test enviroment takes more than few hours.

Fuck off, let me do this shit, and understand its not just apt-getting dependencies for fuck sakes.

!rant
TL;DR: Can anyone recommend or point at any resources which deal with best practices and software design for non-beginners?

I started out as a self-taught programmer 7 years ago when I was 15, now I'm computer science student at a university.
I'd consider myself pretty experienced when it comes to designing software as I already made lots of projects, from small things which can be done in a week, to a project which i worked on for more than a year. I don't have any problems with coming up with concepts for complex things. To give you an example I recently wrote a cache system for an android app I'm working on in my free time which can cache everything from REST responses to images on persistent storage combined with a memcache for even faster access to often accessed stuff all in a heavily multithreaded environment. I'd consider the system as solid. It uses a request pattern where everthing which needs to be done is represented by a CacheTask object which can be commited and all responses are packed into CacheResponse objects.

Now that you know what i mean by "non-beginner" lets get on to the problem:

In the last weeks I developed the feeling that I need to learn more. I need to learn more about designing and creating solid systems. The design phase is the most important part during development and I want to get it right for a lot bigger systems.
I already read a lot how other big systems are designed (android activity system and other things with the same scope) but I feel like I need to read something which deals with these things in a more general way.

Do you guys have any recommended readings on software design and best practices?

Whoever named memcached: fuck you with an open umbrella. It was a bright fucking idea when there already exists a memcahe extension for php. Finding good php examples is impossible when all these idiots name theyr example posts memcached and use memcache class in the code. Fuck.

Is GraphQL worth it? It promisses to keep some load away from backend programmers but what about this scenario:
There's a list of items with scroll load/infinite scroll. There can be several filters as well as the Option to change the ordering of the list items.
With "traditional" REST, I'll hit the DB with one request, get the data in the right order to the backend, might itterate over it once to add additional information, cache the result in Redis/Memcache and send it off.
Using GraphQL, the frontend has to load all entries first, sort them in JS (which probably is slow on mobile devices), and then display it. No matter how "expensive" the query is, there's no caching.

Is that about it? Did I get something backwards?

Caching in Prestashop 1.6 (idk about 1.7) is fucking bullshit. I don't know who made it but he surely must be an idiot. There is no way that the cache is going to speed up your website after a few days of using it.
Memcache/d - For some strange reason, it gets slower and slower after just a few hours. There is literally almost no entries in memcache, but it becomes slower than without cache? WTF
APC - Do you have multiple websites running? You are out of luck. Do you make a change to your website? Restart PHP to see changes. WTF
Redis - Same as APC, but you have to run flushall manually. WTF
CacheFS - God, this is a fucking monstrosity. It rapes the storage drives so hard, it is like running a fucking benchmark nonstop. 400-600MB writes are completely "normal". I have no idea, what is it doing tho. I would expect that writing ~3MB file to disk doesn't require over 100MB/s disk write for 2(!) or more seconds. Also, it doesn't clean up after itself, so after a few days you are out of disk inodes and you have to setup CRON to clean this shit up regularly. In the end, it makes your website fast, but only as long as you have <={number of CPU cores} customers shopping. Then, it becomes a complete disaster and requests are taking 5+ seconds to finish.

I know it's not made to be resilient in any way, only fast, as fast as possible, but man, the memcache_tool script just made my life a million times easier by facilitating a complete data transfer between two memcache instances, allowing for a rolling update without any session data loss!

...One day... I hope it can be migrated to redis... But for now... Thanks lord for the dump command and the wrapper script <3