SQL
genenerate_series Updated 2025-07-16 SQL transaction isolation level Updated 2025-07-16
Each transaction isolation level specifies what can or cannot happen when two queries are being run in parallel, i.e.: the memory semantics of the system.
Remember that queries can affects thousands of rows, and database systems like PostgreSQL can run multiple such queries at the same time.
Implementation specifics:
Type-II superconductor Updated 2025-07-16
Charlie Wilson's War Updated 2025-07-16
Agilent Technologies oscilloscope Updated 2025-07-16
Ciro Santilli's bad old event memory Updated 2025-07-16
Ciro Santilli has a bad memory for events that happened a medium time ago, for example in order of months/years. Especially if they are one-off things that have no relation to anything else.
For example, Ciro never remembers which places he travelled to just once, and who was in each trip! He has images of several places he travelled to in his head, and would recognize them, but he just doesn't know where they were!
Another example, Ciro was looking at the carpet at their house, and asked where it came from. His wife replied immeidately: from Bercy shopping quarter in Paris about 10 years ago, and you took it on your back for a long walk until we could find the bus back home because we were concerned it wouldn't fit in the train!
The same goes for scenes from movies and passages from music, which explains why Ciro's art consumption focuses on innovative discrete "what happened" and "general gist" ideas, rather than, analog details such as colors and shapes.
Going back even further in time, Ciro starts to forget the less close friends he had, because the events start to fade away.
Paradoxically however, Ciro believes that this bad memory is one of his greatest strengths and key defining characteristics, because it leads Ciro to want to write down every interesting thing he learns, which motivated OurBigBook.com and his Stack Overflow contributions and his related Ciro Santilli's documentation superpowers.
It also somewhat leads Ciro to like physics and mathematics, because in these fields you "can deduce everything" from very few base principles, so if you forget them, it does not matter that much as you can re-deduce stuff over and over. Which is somewhat where the high flying bird attitude comes from. It is hard to go deep when you have to re-prove everything every time. But the upside is that anything that sticks, does so because it has a broad net to stick to, and therefore allows Ciro to make unusual and unexpected connections that others might not.
Ciro believes that there are two types of people, and most notably software engineers, which are basically data wranglers: those with bad memory and those with good memory.
Those with bad memory, tend to focus on automating and improving their processes a lot. They take much longer to do one-off specific deep knowledge tasks however.
The downside of the good memory ones is that sooner or later they will find tasks that no matter how much memory they have, they cannot solve without automation, and they will fail at those.
This dichotomy also explains why Ciro sucks at code reviews, but is rather the person who runs the interesting patches by himself and finds some critical problems that the more theoretical code reviewers missed.
If Ciro had become a scientist, he would without doubt be an experimentalist, just like in this reality he is a GDB/runtime person rather than a "static source analysis" person. Those who have bad memory prefer to just run experiments over and over and observe system state at runtime.
Other effects of having a bad memory include:
- code duplication, or a constant fear of it at least, because Ciro forgets that some functionality exists already
- meeting aversion, because everything that is not recorded will fade away
- passion for backward design, because by the time a piece of knowledge learnt in school might be useful (and 99.99% won't), it will have been long forgotten
Related: jakobschwichtenberg.com/about/ from Jakob Schwichtenberg:
In some sense, one of the biggest benefits I have over other people in physics is that I'm certainly not the smartest guy! I usually can't grasp complex issues very easily. So I have to break down complex ideas into smaller chunks to understand it myself. This means, whenever I describe something to others, everyone understands, because it's broken down into such simple terms.
On C2 wiki, therefore it cannot be wrong wiki.c2.com/?QuasiGreatTeacher:
Closure table Updated 2025-07-16
Krusader Updated 2025-07-16
The most powerful GUI file manager ever?? Infinite configurability??
Ciro Santilli wasted some time on it before he gave up on file managers altogether and started using only the CLI with a few aliases.
Lagrange's four-square theorem Updated 2025-07-16
x86 Paging Tutorial ARM Updated 2025-07-16
Information about ARM paging can be found at: cirosantilli.com/linux-kernel-module-cheat#arm-paging
x86 Paging Tutorial Basic TLB operation Updated 2025-07-16
After a translation between linear and physical address happens, it is stored on the TLB. For example, a 4 entry TLB starts in the following state:
valid linear physical
----- ------ --------
> 0 00000 00000
0 00000 00000
0 00000 00000
0 00000 00000The
> indicates the current entry to be replaced.And after a page linear address and after a second translation of
00003 is translated to a physical address 00005, the TLB becomes: valid linear physical
----- ------ --------
1 00003 00005
> 0 00000 00000
0 00000 00000
0 00000 0000000007 to 00009 it becomes: valid linear physical
----- ------ --------
1 00003 00005
1 00007 00009
> 0 00000 00000
0 00000 00000 Chemiosmosis Updated 2025-07-16
Chemistry course of the University of Oxford Updated 2025-07-16
Handbook 2019/2020: web.archive.org/web/20210211192812/http://teaching.chem.ox.ac.uk/Data/Sites/58/media/courseinfo/ug-handbook-chemistry-2019-20.pdf
At teaching.chem.ox.ac.uk/undergraduate-course-handbook.aspx there's a paywall, but Google found the PDF it anyways.
www.ox.ac.uk/students/academic/guidance/undergraduate/handbooks in theory links to all handbooks, but some are likely paywalled. But Google can generally find them anyways.
Ciro Santilli's biography Updated 2025-07-16
Maybe Ciro Santilli should do something useful and remarkable so that someone might actually want to read his biography in the first place. But hey, procrastination.
Ciro Santilli was born in Brazil in the small/medium city of Rio Claro, São Paulo (~200k people in 2020) in the State of São Paulo in 1989 AD.
The family then moved to Jundiaí in 1995, and then finally to Santos, São Paulo, Brazil in 1997.
At the age of 10, Ciro Santilli spent 10 months in Coventry, United Kingdom, where he greatly improved his English.
After Coventry, Ciro's family went back to Santos, São Paulo, Brazil, which made a deep impression on Ciro, until he Ciro Santilli's undergrad studies at the University of São Paulo in 2007.
In 2010, as mentioned at Section "Ciro Santilli's formal education", Ciro as admitted in a double degree program at the École Polytechnique, France, where he stayed until 2013. Going to France was a mind blowing, life changing event.
SQLite import CSV Updated 2025-07-16
Steven Pruitt Updated 2025-07-16
Wikipedia edit request Updated 2025-07-16
Chess engine Updated 2025-07-16
x86 Paging Tutorial Copy-on-write Updated 2025-07-16
Those page faults only happen when a process tries to write to the page, and not read from it.
When Linux forks a process:
- instead of copying all the pages, which is unnecessarily costly, it makes the page tables of the two process point to the same physical address.
- it marks those linear addresses as read-only
- whenever one of the processes tries to write to a page, the makes a copy of the physical memory, and updates the pages of the two process to point to the two different physical addresses
Node.js SQLite bindings Updated 2025-07-16
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