Pocket OLAP in Javascript and IndexedDB performance

Hello, Habr! 3r33333.  
Recently, I decided to test jаvascript performance using the example of creating a simple WEB application that can build pivot tables using weakly structured data as a source. I did not intend to repeat all the functionality of Excel or adult OLAP systems, but I wanted to test the performance of jаvascript in general and IndexedDB in particular on various desktop and mobile browsers. Looking ahead, I’m saying that having completed the first stage of the work - building a pivot table with a single-pass algorithm for storing facts (indexing frequently used sections ...
+ 0 -

Bleeding someone else's accounts has become a criminal offense in South Korea

 3r366. 3r3-31. Bleeding someone else's accounts has become a criminal offense in South Korea  3r366.
 3r366. A few months ago, the South Korean government acted with the initiative to make pumping (boosting) other people's accounts a criminal offense. Officials offered to fine violators for $ 1?000 and put them in jail. Now this bill passed r3r346. and he entered into force.
 3r366. According to industry experts, three factors exert a negative influence on eSports and the whole sphere of online games: various kinds of cheats, third-party game servers and professional boosters. In South Korea, they decided to take the protection of their gaming industry seriously.

 3r366. No...
+ 0 -

Frankie Zapata for The Verge: “Turbojet fuel will help melt reinforced concrete skepticism”

Frankie Zapata for The Verge: “Turbojet fuel will help melt reinforced concrete skepticism”(We analyze the marketing articles of the Frenchman Frankie Zapata. There is dust in the eyes and many useful things.) 3r-3263.  
15 April 201 6
This week, one of the most talked about things is a weird video of a person who seems to have a real hoverboard equipped with a jet engine. The video was published by Zapata Racing, which released water versions of these aircraft for several years. The difference is that they have always been tied to some kind of personal watercraft. This new Flyboard Air, as CEO Frankie Zapata calls it, is something completely different.
On Monday...
+ 0 -

Work with a database from the application

 3r33400. 3r3-31. 3r33383. In the beginning I will identify some of the problems and features when working with the database, show the holes in the abstractions. Next, we will examine a simpler abstraction based on immutability. 3r33333. 3r33381.  3r33400. 3r33383. It is assumed that the reader is somewhat familiar with the patterns Active Record , Data Maper , Identity Map and Unit of Work . 3r33333. 3r33381.  3r33400. 3r33383. Problems and solutions are considered in the context of sufficiently large projects ...
+ 0 -

The story about DDR? SPD and original Chinese manufacturers

The story about DDR? SPD and original Chinese manufacturersIn this article I will tell you how SPD patch on a notebook memory plate, due to the original reason, not related to the fact that I had an old MacBook, but on the contrary, a new computer and a new memory bar (both from ???), and how it danced with a tambourine.
On Habré there are already similar articles times and two , but I used other programs and another solution, so I decided to write another similar article, in the hope that it would be useful to someone.
And for those who will not, I will try to present the situation in the form of a story, and not a stupid manual, so ...
+ 0 -

Some dictionary internals in CPython (and PyPy)

Some dictionary internals in CPython (and PyPy) 3r3407. 3r3-31. The internal structure of dictionaries in Python is not limited to bucket and closed hashing alone. This is an amazing world of shared keys, caching hashes, DKIX_DUMMY and quick comparisons that can be made even faster (at the cost of a bug with an approximate probability of 2 ^ -64).
 3r3407. If you don’t know the number of elements in the newly created dictionary, how much memory is spent on each element, why now (CPython 3.6 and later) the dictionary is implemented with two arrays and how does this relate to maintaining the insertion order, or simply didn’t watch the ...
+ 0 -

How do you like it, Ilon Musk: BMW and Porsche have developed a system that charges electric vehicle batteries in just 3 minutes

3r3-31. How do you like it, Ilon Musk: BMW and Porsche have developed a system that charges electric vehicle batteries in just 3 minutes  

Electro-gas station in Bavaria, Germany. Source: BMW Group

Operation of electric vehicles is becoming increasingly simple, thanks to both the improvement of the vehicles themselves and the gradual development of the relevant infrastructure in different countries. One of the most difficult problems is fast charging of electric vehicle batteries. This is necessary in order to full charge did not have to wait for hours.
Earlier, Tesla Inc introduced a technology that allows you to replenish 80% of the battery in just 15 minutes. This is a Tesla Supercharger. A typical Tesla system charges ...
+ 0 -

Oracle Bitmap Index Techniques

Oracle Bitmap Index Techniques 3r3196. 3r3-31. And again, good evening! 3r3181.  3r3196. 3r3181.  3r3196. We start the second stream of our new course 3r336. "Relational DBMS" 3r3184. which we did a little bit after the first run: additional classes on MySQL and Postgres clusters, docker was in demand, and various “file improvements”. So wait for open lessons (in which part of old topics have been carried out) and interesting materials. Today we delve into the techniques of Oracle. 3r3181.  3r3196. 3r3181.  3r3196. Go. 3r3181.  3r3196. 3r3181.  3r3196. Oracle Bitmap indices are very different from standard B-tree indices. In ...
+ 0 -

Numerical modeling in a large industrial company

Numerical modeling in a large industrial company 3r3119. 3r31-10.  
Hello, Habr and his dear readers! 3r31-10.  
I was lucky. I work in a large metallurgical company, where innovations are valued, there is modern equipment, a good laboratory base, and partners all over the world. But this does not mean at all that it was easy to introduce and make needed a new research tool. I want to tell why we took up this topic, what obstacles we faced, what results we managed to achieve and where we want to develop. I will pay special attention to the question of why, with numerical simulation, we came to our clients. Welcome under the cut! 3r31-10...
+ 0 -

Open lesson "Feature Engineering on the example of the classic dataset of the Titanic"

 3r33333. 3r3-31. Hello again!
 3r33333. In December, we will start training for the next group "Data scientist" therefore, there are more and more open lessons and other activities. For example, just recently, a webinar was held under the long title “Feature Engineering on the example of the classic dataset of the Titanic”. He spent 3r3327. Alexander Sizov
- an experienced developer, Ph.D., an expert on Machine /Deep learning and a participant in various commercial international projects related to artificial intelligence and data analysis.
 3r33333. Open lesson took ...
+ 0 -