Custom aggregate and window functions in PostgreSQL and Oracle

 
In this article, we'll see how to create custom aggregate and windowed (in Oracle terminology - analytical) functions in two systems. Despite the differences in the syntax and, in general, the approach to extensibility, the mechanism of these functions is very similar. But there are differences too.
 
 
It must be admitted that its own aggregate and window functions are quite rare. Window functions generally for some reason are traditionally classified as "advanced" SQL and are considered difficult to understand and master. Here we should deal with those functions that already exist in the DBMS!
 
 
Why, th...
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We write a Telegram-bot on Go to search Wikipedia

We write a Telegram-bot on Go to search WikipediaTable of contents [/b]
 
Create a bot
 
We write the code
 
Expand the bot
 
Conclusion
 
 
Now telegrams are very popular and writing bots for him has become a kind of hello world of our days, therefore, at the thought of what you can write now, many immediately think of writing telegrams for the bot.
 
As a student, like all students, I often visit Wikipedia in parallel, giving time and a telegram. It was decided to find a way to combine the location in the telegram and the opportunity to find the material I wanted in Wikipedia, in fact, this bot appeared (at the time of writing the bot, I did not ...
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Java and Project Reactor

Java and Project Reactor
 
Hello! My name is Lyokha, and I work as a backend developer in FunCorp. Today we will talk about reactive programming, the Reactor library and a little about the web.
 
Reactive programming is often "exposed", but if you (like the author of the article) still do not know what it is - sit back, try to figure it out together.
these are your manifestos with details of , but worth it.
 
And here is the web?
 
There are rumors that if you build your system reactively, according to all the canons of Reactive Manifesto, starting with the HTTP server and ending with the database driver, you can call the second ...
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Scrum vs Kanban: what's the difference and what to choose?

When there are options - it's important not to make a mistake and study all the details and possibilities to stay at the best. Choosing between development management methods is not always easy, especially if it's Scrum and Kanban.
 
 
Scrum vs Kanban: what's the difference and what to choose?
 
is written. from Carl Wiggers and Joy Beatty.
 
 
 
Often, recently, a project is a start-up. In the context of startups comes to mind " customer development "(The original technique is remarkably described by Steve Blank).
 
 
In fact, during customer development, we test our hypotheses ...
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Notification to the mail in real time. Really? Or how to make Alert on Splunk

How long does it take since the emergence of some important event before the reactionary actions? Often very much! One of the factors affecting the reaction time is the untimely informing of the personnel responsible for making decisions.
 
 
Notification to the mail in real time. Really? Or how to make Alert on Splunk  
 
Today we will tell you how to receive notifications about the occurrence of important security incidents, the critical state of IT systems, significant deviations from the norm of various indicators or other events interesting for you in real time and in a convenient format, in particular by e-mail.
 
 
To implement alerts, or in other words alerts, we will be ...
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"I'll have to write it myself. They sat down and wrote ": the life of the developers of the laboratory cluster of supermassives in Sbertech

There is a myth that banks are very rigid structures, in which there is no place for experiment. To disprove this myth, we conducted a short interview with Valery Vybornov, head of the department for the development of a laboratory cluster of supermassives in Sberbank-Technologies. In their team, they are not afraid to use the full power of Scala, Akka, Hadoop, Spark, and even write prototypes for Rust.
 
"I'll have to write it myself. They sat down and wrote ": the life of the developers of the laboratory cluster of supermassives in Sbertech
 
The main questions:
 
 
Discussion of an example of a pilot project (working with a social graph) with technical details;
 
Used languages ​​and technologies (Scala, Akka, Hadoop, Spark, Rust, etc.);
 
Can ...
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Find it if you can. How to select messages in the general stream

Each of us is familiar with the problem of a huge mass of alerts from shops, banks, car dealers and other organizations that are constantly falling on all electronic and not very electronic channels. We used to call it spam, developed reflexes of lightning-speed removal, set up spam filters, or just do not notice such messages. And we reconciled ourselves to the fact that it is practically impossible to find useful messages among them.
 
 
Find it if you can. How to select messages in the general stream
 
 
Is it possible to make electronic channels more efficient, somehow help recipients to find the right letters? The matter is complicated by the fact that while artificial ...
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Production of information systems. Part 1. Starting point

Production of information systems. Part 1. Starting point

I INTRODUCTION


From the chaos somehow order is born.
 
Some of them learn about it from newspapers with a significant delay, and some on bitter experience on the spot and in the process of creating this order.
 
Michael Bulgakov.
Looking through the articles devoted to this or that topic related to the creation of software, I often watch, here is the picture: a narrow topic is revealed interestingly and professionally, but when the nuances at the junction, on the other side of the main question are touched, there are discrepancies and failures in general understanding the process of production ...[/h]
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Batch processing of images in Windows with ImageMagick. Part I

ImageMagick - A free and cross-platform editor for working with graphics.
 
It consists of several console utilities. His capabilities can not be counted as stars in the sky.
 
There are a lot of in the network. examples , how to use it. But most of them are for Linux or PHP. For Windows, their cat cried. It's time to fill the gap.
 
Q16 .
 
 
During installation, check the checkboxes:
 
 
Batch processing of images in Windows with ImageMagick. Part I
 
 
Thus, we get the whole set of utilities and add them to the system variable path.
 
 
[h2] Batch compression ...[/h]
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Thymeleaf Tutorial: Chapter 4. Standard Expression Syntax

Table of contents
 
 

4 Standard Expression Syntax /Standard Expression Syntax


 
We will take a small break in the development of our virtual grocery store to learn about one of the most important parts of the Standard Thymeleaf dialect: j with the Standard Thymeleaf expression syntax.
 
 
We have already seen two types of valid attribute values, expressed in this syntax: messages and variables:
 
 

Welcome to our grocery store!

 

Today is:
13 february 2011

 
www.thymeleaf.org
 
Relative URLs:
 
 
Relative on the page: user /login.html
 
Relative ...[/h]
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