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Hussein Nasser @hnasr.bsky.social · 25/06/2026

When a client process that is connected to a postgres instance is killed, what happens to the backend postgres process and all the locks it holds?

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Hussein Nasser @hnasr.bsky.social · 21/06/2026

TLB misses are expensive. But TLB misses that trigger page faults are even more expensive. Choice of processes vs threads can exacerbate this

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Hussein Nasser @hnasr.bsky.social · 18/06/2026

I keep forgetting that VACUUM FULL doesn’t analyze the table. Spent 20 minutes wondering why my query was using a bitmap scan instead of index only. Need to explicitly use VACUUM FULL, ANALYZE

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Hussein Nasser @hnasr.bsky.social · 14/06/2026

Watch out for APIs (especially OOP getters) that may look benign but perform an expensive operation. Calling these (especially in a tight loop) will result in a performance degradation (massive singleton queries) and just looking at the code from outside will not reveal the issue.

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Hussein Nasser @hnasr.bsky.social · 12/06/2026

The audio version of Root Cause: Stories and Lessons from Two Decades of Backend Engineering Bugs, narrated by yours truly is live on Amazon and Kobo! I hope you enjoy it, thank you all the kind words and support. Not a mention of AI in the book, so In case you need a break amzn.to/3QHjQDz

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Hussein Nasser @hnasr.bsky.social · 11/06/2026

Root Cause will make you look and think of system internals from a different lens. Grab your copy Amazon: amzn.to/4cfQjJj b&n www.barnesandnoble.com/w/root-cause...

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Hussein Nasser @hnasr.bsky.social · 10/06/2026

Note to self, VACUUM (FULL) marks the visibility maps of all tables to 0, making index only scans heap-fetch. You have to follow it with a VACUUM; to get them updated. pg 17. Didn’t try 18.

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Hussein Nasser @hnasr.bsky.social · 07/06/2026

In the end, AI will produce more bloated products for us to troubleshoot and fix. If you are a good software troubleshooter who understands the fundamentals. you will be on high demand. And Your skillsets are deadly.

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Hussein Nasser @hnasr.bsky.social · 06/06/2026

Memorizing trick programming questions and answering interviews flawlessly as you may know isn’t productive. Coming up with your own solution on the fly, no matter how inefficient or bad you think it is 100 times better.

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Hussein Nasser @hnasr.bsky.social · 04/06/2026

These days… I get excited to see typos while reading and relish the long pauses and even rambling while watching videos. Really… I’ll take any glimpse of humanity left.

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Hussein Nasser @hnasr.bsky.social · 02/06/2026

To understand locking in PostgreSQL I built pglocks dot org. I then compiled that locking techniques and other database fundaments I learned throughout my years in this database course. If you are interested in database systems, checkout my 30 hours database course, courses.husseinnasser.com

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Hussein Nasser @hnasr.bsky.social · 21/05/2026

Root Cause: Stories and Lessons from Two Decades of Backend Engineering Bugs No best practices. no recommendations. just stories of the most interesting bugs and how I solved them I hope you enjoy it amzn.to/4cKfZhe

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Hussein Nasser @hnasr.bsky.social · 14/05/2026

The scars behind a piece of software innovation are not transferable.

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Hussein Nasser @hnasr.bsky.social · 10/05/2026

You cannot make a good implementation until you first make a naïve one.

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Hussein Nasser @hnasr.bsky.social · 07/05/2026

IPv8 draft is out. With 8 bytes instead of 4 bytes. The leading 4 bytes is the ASN (ISP). Compatible with IPv4. I am interested in the overhead cost of this conversion at scale.

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Hussein Nasser @hnasr.bsky.social · 03/05/2026

5 chapters recorded for the audio book of Root Cause. Getting close. You are getting additional content with the audio book as am adding commentary as I remember memories / stories during the chapter reads

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Hussein Nasser @hnasr.bsky.social · 03/05/2026

If have 4-6 years of experience in the backend and want to elevate your skills, consider grabbing the advanced Backend engineering Bundle. It consists of three fundamental courses taken in this order for an effective learning roadmap.

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Hussein Nasser @hnasr.bsky.social · 30/04/2026

My new book Root cause - Lessons from two decades of backend engineering bugs Each chapter is an interesting bug, filled with diagrams, fundamental concepts, and most importantly journey of discovery. Grab your copy amzn.to/4cKfZhe

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Hussein Nasser @hnasr.bsky.social · 26/04/2026

Even if you think you are right keep an open mind that you may be wrong. You will be surprised as how much right-er you could be when you do that. When there is doubt there is room to improve, to learn and explore. When you think you are right, exploration halts.

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Hussein Nasser @hnasr.bsky.social · 25/04/2026

I designed this course for developers and engineers who built backend and frontend apps and would like to take their skills further in understanding the full stack and how to identify performance bottlenecks on their backend applications. Grab it here courses.husseinnasser.com

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Hussein Nasser @hnasr.bsky.social · 23/04/2026

If you found yourself hoping a fix works, know that part of you doesn’t understand the problem very well. That part of you wants the bug gone. Resisting the bug creates fear. If you wish to hope, hope for an error so you can understand why what you applied didn’t work the art of trial and error.

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Hussein Nasser @hnasr.bsky.social · 19/04/2026

OOP and Databases don’t mix well. When you force them to mix, you get a lipstick. Also know as ORMs.

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Hussein Nasser @hnasr.bsky.social · 17/04/2026

Announcing my new book, Root Cause, Stories from two decades of backend engineering bugs paperback amzn.to/4cKfZhe ebook amzn.to/4cfQjJj

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Hussein Nasser @hnasr.bsky.social · 16/04/2026

Trying to explain a brilliant data structure (such as bloom filter) often falls flat and unappreciated. This is because the context and pain and the need behind it is often omitted or sometimes not even known. Instead a contrived reasoning is provided leaving people more puzzled.

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Hussein Nasser @hnasr.bsky.social · 15/04/2026

I wrote a new book that has been in the works for years. It is called Root Cause, and it is for those who enjoy the art of backend engineering. amzn.to/4cKfZhe

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Hussein Nasser @hnasr.bsky.social · 10/04/2026

It feels good to understand what goes on behind the scenes in the database. It boils down to the fundamentals that I compiled in this course. I get messages from people who passed interviews, got hired, promoted and improved their apps. Grab your copy databases.win

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Hussein Nasser @hnasr.bsky.social · 09/04/2026

Confidence is the absence of doubt

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Hussein Nasser @hnasr.bsky.social · 05/04/2026

If you ever used the /*+ APPEND */ Oracle hint to bulk insert rows into a table, you won’t be able to read the table in the same transaction. If you try you will get this error. ORA-12838: cannot read/modify an object after modifying it in parallel.

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Hussein Nasser @hnasr.bsky.social · 03/04/2026

To build performant backend applications, it is better to start from first principles. Head to courses.husseinnasser.com for a coupon. I recommend getting the OS course as it is the basis to unlocking all other courses.

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Hussein Nasser @hnasr.bsky.social · 02/04/2026

Any software you build to solve a problem will have a limitation. The danger is in not knowing what the limitations are before building it. To make this concrete, if database X is advertised as a better alternative of database Y, vendors of X will praise the “good” of X, highlight the “bad” Y

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Hussein Nasser @hnasr.bsky.social · 29/03/2026

Code with fewer lines is not always simple code. Fewer lines of code often indicate an abstraction. Abstractions are not inherently simple; they create the illusion of simplicity. They don’t remove complexity—they hide it. This hidden complexity can cause engineers to lower their guard.

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Hussein Nasser @hnasr.bsky.social · 26/03/2026

Imposter syndrome is like a self recursive function.

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Hussein Nasser @hnasr.bsky.social · 22/03/2026

If you sit with a bug long enough, the root cause will reveal itself. Don’t try to get “rid” of it, because that will create frustration and aversion. Enjoy the exploration of the root cause removing yourself from blame and responsibility. When you do, you will feel yourself level up.

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Hussein Nasser @hnasr.bsky.social · 19/03/2026

Will RAM become so expensive that we’ll be forced to actually write efficient software? just like the early days of computing

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Hussein Nasser @hnasr.bsky.social · 19/03/2026

Giving out 200 free coupons of my courses for Eid. هنالك ألم كثير في العالم، أتمنى انه نحتفل في السنة القادمة في عالم بدون حروب... courses.husseinnasser.com NGINX course NGINXEID2026 OS course OSEID2026 Real time websockets WSEID2026 Troubleshooting backend PFEID2026 Database DBEID2026

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All Hussein Nasser Courses List with Coupons

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Hussein Nasser @hnasr.bsky.social · 15/03/2026

what happens if you lose power halfway through writing to the data files in the database? I explore this on my substack open.substack.com/pub/hnasr/p/...

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Hussein Nasser @hnasr.bsky.social · 13/03/2026

My favorite thing about software engineering is making it transparent. Node is one of the most popular runtimes used on backend engineering yet I feel it is the least understood. I surely ran into this way at times.

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Hussein Nasser @hnasr.bsky.social · 08/03/2026

How I design software open.substack.com/pub/hnasr/p/...

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Hussein Nasser @hnasr.bsky.social · 05/03/2026

Fully understanding existing components and how they work is something we rarely do. We throw our hands and blame the component, the tool, the framework, the language, the database but rarely we blame our lack of understanding.

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Hussein Nasser @hnasr.bsky.social · 01/03/2026

asynchronous calls are a mirage. There always something synchronous being blocked upstream.

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Hussein Nasser @hnasr.bsky.social · 01/03/2026

If have 3-5 years of experience in the backend and want to elevate your skills, consider grabbing the advanced Backend engineering Bundle. The Advanced Backend Engineering Bundle courses.husseinnasser.com/bundle Coupons: BACK-MAR2026-A, PF-MAR2026-A , WS-MAR2026-A

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