FOR UPDATE locks the row for other blocking transactions (including another select for update)
The weaker form that only locks updates and deletes is called FOR SHARE.
Transaction isolation levels do not make a difference here.
So the article is correct that SELECT FOR UPDATE will ensure that another concurrent SELECT FOR UPDATE transaction never acquire the same row (it will block), though nothing prevents other non-blocking selects to query this row concurrently.
You can think of it as usual locks - only the threads that explicitly use the same lock have the mutual exclusion guarantees. If there’s another thread that does not acquire the lock and tries to access the critical section - it will be able to do so.
After using several bank clients in different countries I can confidently say that some banks just have bad UI, and other banks are just good enough.
I don't think human language is simpler than good simple interface, though it can shine as a guide or navigator.
I love all the series about writing your own X in 100 lines of code.
It gives you the understanding of technology and removes a lot of unnecessary details.
- Russian-Ukraine war loses its momentum on the eastern front, hot war continues.
- Azerbaijan is launching full-scale invasion to Nagorno-Karabakh, taking it over in a Blitzkrieg with the support of Turkey.
- Russia is forcing Armenia to join Russian Union State, massive protests in Yerevan.
- Pro-Russian government is replacing Belorus president who is forced to resign, massibe protests in Minsk.
- China is preparing for a full scale invasion to Taiwan in 2024.
- Crypto industry crumbles into dust under heavy regulation.
- Meta is stepping back from the Metaverse, moving this research to a separate entity. Meta stocks are all-time low.
- First AI-generated celebrities.
Ok you got me, I feel nostalgic.
What strikes me most is that those people from 90th were putting their creativity into something only handful of people will ever see, they were effectively shouting to void.
I would love to be still able to discover low-ranging websites like this. I remember somebody shared some alternative search engine?