The Backend Engineering Show with Hussein Nasser

Light episode today let's have some fun with Q&A, I collected some questions on Twitter and YouTube community and I'm going to attempt to answer them here. Support my work on PayPal https://bit.ly/33ENps4 Become a Member on YouTube https://www.youtube.com/channel/UC_ML5xP23TOWKUcc-oAE_Eg/join 🧑‍🏫 Courses I Teach https://husseinnasser.com/courses

In this episode, we will discuss NULLs in database systems. I’ll go through the following: What is Null? NULLs persistence Whether you store a 0 or 2 billion value in the field 32bit integer field it costs 32 bit when you store a NULL in 32 bit integer field we save 32 bit but add overheads When NULLs are naughty Semantics and inconsistent result Select count(*). Includes nulls count(column) ignores nulls T is NULL returns the null rows T is NOT NULL returns not null rows T In (NULL) returns nothing T not in NULL returns nothing Some database don’t index nulls When NULLs are useful I don’t have value , I don’t wish to provide a birthday not applicable field for certain use cases but not others fat tables (denormlization) Fat tables with many columns makes your rows longer which means fewer rows fit in your page (show pic).. NULLs help here .. that are NULL, it yields shorter rows, instead of storing a default 0 value Support my work on PayPal https://bit.ly/33ENps4 Become a Member on YouTube https://www.youtube.com/channel/UC_ML5xP23TOWKUcc-oAE_Eg/join 🧑‍🏫 Courses I Teach https://husseinnasser.com/courses

The open web application security project is a recognized entity that helps developers identify critical security vulnerabilities to build secure web applications. In this video I will go through the 10 vulnerabilities and explain each one and give examples and anecdotes from real life examples. 0:00 Building Secure Backends 2:30 Injection 4:50 Broken Authentication 6:43 Sensitive Data Exposure 11:00 XML External Entities (XXE) 13:45 Broken Access Control 17:00 Security Misconfiguration 19:00 XSS 22:45 Insecure Deserialization. 24:48 Using Components with Known Vulnerabilities. 26:00 Insufficient Logging & Monitoring. Resources https://owasp.org/www-project-top-ten/ Cards 2:50 SQL Injection https://www.youtube.com/watch?v=Azo9tDUtC9s 4:20 Best practices building REST https://www.youtube.com/watch?v=6zHWU7zBep0&list=PLQnljOFTspQUybacGRk1b_p13dgI-SmcZ&index=4 8:30 TLS playlist youtube.com/playlist?list=PLQnljOFTspQW4yHuqp_Opv853-G_wAiH- 15:00 HTTP Smuggling https://www.youtube.com/watch?v=PFllH0QccCs 19:22 XSS https://www.youtube.com/watch?v=pD6C1-zSxIM 25:10 OpenSSL Crash https://youtu.be/aDPQ0_MyRnc Support my work on PayPal https://bit.ly/33ENps4 Become a Member on YouTube https://www.youtube.com/channel/UC_ML5xP23TOWKUcc-oAE_Eg/join 🧑‍🏫 Courses I Teach https://husseinnasser.com/courses

Caching is the hardest problem in building software, and having the browser cache is not any different. In this video, I'll discuss Jake Archibald's article https://jakearchibald.com/2016/caching-best-practices/ 0:00 Intro 2:00 Pattern 1: Immutable content + long max-age 5:40 Pattern 2: Mutable content, always server-revalidated 8:00 max-age on mutable content is often the wrong choice 12:20 CDN and Caching Article https://jakearchibald.com/2016/caching-best-practices/ https://twitter.com/jaffathecake

Write Amplification Is a phenomenon where the actual writes that physically happen are multiples of the actual writes desired. In this episode, I'll discuss 3 types of write amplifications and their effects on performance and lifetime of storage mediums. 0:00 intro 2:00 Application write amplification 4:30 Database write amplification 9:30 SSD Disk write amplification 16:00 SSD hates BTrees 20:00 summary Resources https://en.wikipedia.org/wiki/Write_amplification https://www.cybertec-postgresql.com/en/hot-updates-in-postgresql-for-better-performance/ https://youtu.be/5Mh3o886qpg

Microsoft Had an Outage on April 1st that is caused by DNS surge, let us discuss this. Bonus I’ll also discuss the outage that happened on March 18th cpu 100% utilization RCA - DNS issue impacting multiple Microsoft services (Tracking ID GVY5-TZZ) Summary of Impact: Between 21:21 UTC and 22:00 UTC on 1 Apr 2021, Azure DNS experienced a service availability issue. This resulted in customers being unable to resolve domain names for services they use, which resulted in intermittent failures accessing or managing Azure and Microsoft services. Due to the nature of DNS, the impact of the issue was observed across multiple regions. Recovery time varied by service, but the majority of services recovered by 22:30 UTC. 0:00 April/1st Outage - DNS Issue 13:30 March/18th Outage - CPU 100% RCA https://status.azure.com/en-us/status/history/

Hey Hussein I have a 2 million row table used in my CRUD python app, I’m worried that as the table grow my inserts will slow down, should I consider sharding my database or partition the table? thank you I’m avid of simplicity in design if I can do it in one machine I’ll do it. Sharding/Partitioning are all great inserts are fast, queries are slow 0:00 inserts can be slow 3:00 indexes/stored procedures selects, updates, and deletes can be slow 12:00 add proper indexes. simplicity wins, premature optimization is bad 15:20 crazy things that people say like microservices day 1 scares me

Enabled by default, libcurl supports the use of TLS 1.3 session tickets to resume previous TLS sessions to speed up subsequent TLS handshakes. When using a HTTPS proxy and TLS 1.3, libcurl can confuse session tickets arriving from the HTTPS proxy but work as if they arrived from the remote server and then wrongly "short-cut" the host handshake. The reason for this confusion is the modified sequence from TLS 1.2 when the session ids would provided only during the TLS handshake, while in TLS 1.3 it happens post hand-shake and the code was not updated to take that changed behavior into account. 4:00 http connect https://curl.se/docs/CVE-2021-22890.html

Two malicious commits were pushed to the php-src Git repository maintained by the PHP team on their git.php.net server. The commits were found and reverted two hours after it was committed. PHP is moving to github as a result. Article https://www.bleepingcomputer.com/news/security/phps-git-server-hacked-to-add-backdoors-to-php-source-code/

We have been told to take care of our private key that we use on backend servers without clear instructions as to what could happen when that key is leaked. In today’s backend engineering show I discuss exactly what could go wrong when your backend server private key is leaked. Let us discuss Intro 0:00 What is a Certificate? 1:10 Where is the Private Key used? 4:10 TLS 1.2 with RSA 4:20 Why RSA no longer used 9:00 TLS 1.3 & TLS 1.2 Digital Signature 12:00 How often should you recycle Private Keys 19:00 Resources https://blog.cloudflare.com/advanced-certificate-manager/ https://heartbleed.com/ https://cabforum.org/ https://en.wikipedia.org/wiki/DigiNotar https://www.ibm.com/support/knowledgecenter/en/SSFKSJ_9.0.0/com.ibm.mq.sec.doc/q009960_.html