The Backend Engineering Show with Hussein Nasser

By Hussein NasserTechnology

The Backend Engineering Show with Hussein Nasser episodes

May 25, 2023 Your SSD lies but that's ok | Postgres fsync
fsync is a linux system call that flushes all pages and metadata for a given file to the disk. It is indeed an expensive operation but required for durability especially for database systems. Regular writes that make it to the disk controller are often placed in the SSD local cache to accumulate more writes before getting flushed to the NAND cells.
However when the disk controller receives this flush command it is required to immediately persist all of the data to the NAND cells.
Some SSDs however don't do that because they don't trust the host and no-op the fsync. In this video I explain this in details and go through details on how postgres provide so many options to fine tune fsync
0:00 Intro
1:00 A Write doesn’t write
2:00 File System Page Cache
6:00 Fsync
7:30 SSD Cache
9:20 SSD ignores the flush
9:30 15 Year old Firefox fsync bug
12:30 What happens if SSD loses power
15:00 What options does Postgres exposes?
15:30 open_sync (O_SYNC)
16:15 open_datasync (O_DSYNC)
17:10 O_DIRECT
19:00 fsync
20:50 fdatasync
21:13 fsync = off
23:30 Don’t make your API simple
26:00 Database on metal?

31 min
May 21, 2023 The problem with software engineering
ego is the main problem to a defective software product. the ego of the engineer or the tech lead seeps into the quality of the product.
Fundamentals of Backend Engineering Design patterns udemy course (link redirects to udemy with coupon)
https://backend.husseinnasser.com
18 min
May 11, 20232x Faster Reads and Writes with this MongoDB feature | Clustered Collections
Fundamentals of Database Engineering udemy course (link redirects to udemy with coupon)
https://database.husseinnasser.com

In version 5.3, MongoDB introduced a feature called clustered collection which stores documents in the _id index as oppose to the hidden wiredTiger hidden index. This eliminates an entire b+tree seek for reads using the _id index and also removes the additional write to the hidden index speeding both reads and writes.

However like we know in software engineering, everything has a cost. This feature does come with a few that one must be aware of before using it. In this video I discuss the following
How Original MongoDB Collections Work

How Clustered Collections Work

Benefits of Clustered Collections

Limitations of Clustered Collections
28 min
May 06, 2023 Prime Video Swaps Microservices for Monolith: 90% Cost Reduction
Prime video engineering team has posted a blog detailing how they moved their live stream monitoring service from microservices to a monolith reducing their cost by 90%, let us discuss this
0:00 Intro
2:00 Overview
10:35 Distributed System Overhead
21:30 From Microservices to Monolith
29:00 Scaling the Monolith
32:30 Takeaways
https://www.primevideotech.com/video-streaming/scaling-up-the-prime-video-audio-video-monitoring-service-and-reducing-costs-by-90
Fundamentals of Backend Engineering Design patterns udemy course (link redirects to udemy with coupon)
https://backend.husseinnasser.com
36 min
May 02, 2023 A Deep Dive in How Slow SELECT * is
Fundamentals of Database Engineering udemy course (link redirects to udemy with coupon)
https://database.husseinnasser.com
In a row-store database engine, rows are stored in units called pages. Each page has a fixed header and contains multiple rows, with each row having a record header followed by its respective columns. When the database fetches a page and places it in the shared buffer pool, we gain access to all rows and columns within that page. So, the question arises: if we have all the columns readily available in memory, why would SELECT * be slow and costly? Is it really as slow as people claim it to be? And if so why is it so? In this post, we will explore these questions and more.
0:00 Intro
1:49 Database Page Layout
5:00 How SELECT Works
10:49 No Index-Only Scans
18:00 Deserialization Cost
21:00 Not All Columns are Inline
28:00 Network Cost
36:00 Client Deserialization
https://medium.com/@hnasr/how-slow-is-select-8d4308ca1f0c
40 min
April 07, 2023 AWS Serverless Lambda Supports Response Streaming

Lambda now supports Response payload streaming, now you can flush changes to the network socket as soon as it is available and it will be written to the client socket. I think this is a game changing feature

0:00 Intro
1:00 Traditional Lambda
3:00 Server Sent Events & Chunk-Encoding
5:00 What happens to clients?
6:00 Supported Regions
7:00 My thoughts

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https://backend.husseinnasser.com

14 min
April 06, 2023 The Cloudflare mTLS vulnerability - A Deep Dive Analysis
Cloudflare released a blog detailing a vulnerability that has been in their system for nearly two years. it is related to mTLS or mutual TLS and specifically client certificate revocation. I explore this in details
0:00 Intro
3:00 The Vulnerability
7:00 What happened?
8:50 Certificate Revocation
12:30 Rejecting certain endpoints
17:00 Certificate Authentication
20:30 Certificate serial number
24:00 Session Resumption (PSK)
35:00 The bug
37:00 How they addressed the problem
Fundamentals of Backend Engineering Design patterns udemy course (link redirects to udemy with coupon)
https://backend.husseinnasser.com
44 min
April 06, 2023 The Virgin Media ISP outage - What happened?
BGP (Border gateway protocol) withdrawals caused the Virgin media ISP customers to lose their Internet connection. I go into details on this video.
0:00 Intro
2:00 What happened?
4:11 How BGP works?
11:50 Version media withdrawals
15:00 Deep dive
Fundamentals of Backend Engineering Design patterns udemy course (link redirects to udemy with coupon)
https://backend.husseinnasser.com
24 min
March 30, 2023 GitHub SSH key is Leaked - How bad is this?
GitHub Accidentally Exposed their SSH RSA Private key, this is the message you will get .
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
SHA256:uNiVztksCsDhcc0u9e8BujQXVUpKZIDTMczCvj3tD2s.
Please contact your system administrator.
Add correct host key in ~/.ssh/known_hosts to get rid of this message.
Host key for github.com has changed and you have requested strict checking.
Host key verification failed.
In this video I discuss how bad is this,.
0:00 Intro
1:10 What happened?
3:00 SSH vs TLS Authentication
6:00 SSH Connect
7:45 How bad is the github leak?
15:00 What should you do?
18:50 Is ECDSA immune?
https://github.blog/2023-03-23-we-updated-our-rsa-ssh-host-key/
22 min
March 29, 2023 Cookie Hijacking - How Linus Tech Tips got Hacked
How Linus Tech Tips channel got Hacked

In this short video we explain how was it possible for Linux to get hacked with cookies hijacking.
0:00 Intro
0:47 TLDR what happened
5:10 Cookies in Chrome
7:30 Cookies Hijacking
8:46 Session Tokens (Access/Refresh)
10:00 Remedies

14 min

About The Backend Engineering Show with Hussein Nasser

From the publisher's feed

Welcome to the Backend Engineering Show podcast with your host Hussein Nasser. If you like software engineering you’ve come to the right place. I discuss all sorts of software engineering technologies and news with specific focus on the backend. All opinions are my own.