Blog Columns
Six thematic columns, each with its own dedicated RSS feed.
Database Guru
75posts
Database news, industry surveys, architecture, and best practices.
Cloud-Exiter
66posts
Cloud economics, repatriation, and building sovereign infrastructure.
Postgres Mage
128posts
PostgreSQL ecosystem, internals, extensions, and production tuning.
AI Agent Explorer
98posts
Practical engineering with coding agents, LLMs, AI4DB, and DB4AI.
Travel Notes
12posts
Trips, hikes, landscapes, and field notes across mountains and seas.
Miscellaneous
41posts
Essays, reflections, and personal writing inside and outside of tech.
Statistics Fundamentals: Descriptive Statistics
Statistical analysis is divided into two fields: descriptive statistics and inferential statistics. Descriptive Statistics is the technology for describing or characterizing existing data and is the …
Inferential Statistics: The Past and Present of p-values
The core of inferential statistics lies in hypothesis testing. The basic logic is based on an important argument from philosophy of science: universal propositions can only be falsified, not proven. …
Building an ItemCF Recommender in Pure SQL
Five minutes, PostgreSQL, and the MovieLens dataset—that’s all you need to implement a classic item-based collaborative filtering recommender.
Basic Concepts of Probability Theory
Basic knowledge notes on probability theory: axiomatic foundations, probability calculus, counting, conditional probability, random variables and distribution functions
Starting from /0: Understanding Errors and Exceptions
What happens when you divide by 0 in a computer? The answer isn't fixed - it can differ across different operating systems, programming languages, and even different compilers.
UUID Properties, Principles and Applications
UUID properties, principles and applications, and how to manipulate UUIDs using PostgreSQL stored procedures.
Tag Classification Theory
Recently, I needed to design a tag management system for a business. During the process of organizing existing tags, I developed this theoretical framework.
Switzerland of Northern Xinjiang: Kanas Trekking
I never expected my first outdoor trekking experience would be in Kanas.
Overview of Sorting Algorithms
Sorting algorithms are the most fundamental, widely applicable, and frequently tested algorithms in interviews. This article summarizes classic sorting algorithms: selection sort, insertion sort, …
PostgreSQL MongoFDW Installation and Deployment
Recently had business requirements to access MongoDB through PostgreSQL FDW, but compiling MongoDB FDW is really a nightmare.
Fundamentals of Information Theory: Entropy
Reading notes on 'Elements of Information Theory': What is entropy? Entropy is a measure of the uncertainty of random variables, and also a measure of the information needed to describe random …
Baiji 1509 Training Reflections
I once thought all day but learned nothing, which is not as good as what I learned in a moment. I came to Hangzhou to attend Alibaba's Baiji training to learn from seniors and improve my knowledge …
2014 Year-End Summary
Unable to sleep in the dead of night, spending the last hour of 2014 reviewing this year and looking ahead to next year seems quite appropriate.
On Computational Thinking
A paper for "History of Secrecy and Secrecy Systems" course, discussing computational thinking and its significance in undergraduate education, as well as methods for cultivating computational …
In Praise of Mathematics
What a wonderful subject mathematics is
Humans, Society, and Neural Networks
Neural networks emerged inspired by the human brain, so the operational mechanisms of human society also have various similarities and connections with neural network training. Some thoughts on …
2013 Year-End Summary
In the final half hour of 2013, reflecting on my experiences this year fills me with deep emotion.
Computer Networks and Logistics Systems
Computer networks are like a logistics system, with the only difference being that logistics systems transmit material entities like mail and packages, while computer networks transmit intangible …
Worldview, Values, and Life Philosophy
One inevitably traces back to questions about the world's origins, and answering these questions is the process of establishing one's cornerstone principles.
On the Hierarchy of Knowledge
Through observation and reflection, we can divide the mental process of deepening understanding from accepting knowledge to the highest level of 'enlightenment' into four stages: knowledge, …
Thinking Characteristics of Eastern and Western People
Eastern people emphasize macro-to-micro thinking, while Western people emphasize micro-to-macro thinking. In my view, this is the philosophical root of East-West thinking differences and many macro …
What Exactly Are Natural Numbers?
The concept of natural numbers should have been learned in elementary school. The foundation of all elementary mathematics begins with such a definition. However, when I entered university, I …
Fundamental Concepts of Linear Algebra
Connecting all concepts in linear algebra through one main thread
Views on Love
What ultimately determines romance and marriage?
Statistics Fundamentals: Descriptive Statistics
Statistical analysis is divided into two fields: descriptive statistics and inferential statistics. Descriptive Statistics is the technology for describing or characterizing existing data and is the …
Inferential Statistics: The Past and Present of p-values
The core of inferential statistics lies in hypothesis testing. The basic logic is based on an important argument from philosophy of science: universal propositions can only be falsified, not proven. …
Building an ItemCF Recommender in Pure SQL
Five minutes, PostgreSQL, and the MovieLens dataset—that’s all you need to implement a classic item-based collaborative filtering recommender.
Basic Concepts of Probability Theory
Basic knowledge notes on probability theory: axiomatic foundations, probability calculus, counting, conditional probability, random variables and distribution functions
Starting from /0: Understanding Errors and Exceptions
What happens when you divide by 0 in a computer? The answer isn't fixed - it can differ across different operating systems, programming languages, and even different compilers.
UUID Properties, Principles and Applications
UUID properties, principles and applications, and how to manipulate UUIDs using PostgreSQL stored procedures.
Tag Classification Theory
Recently, I needed to design a tag management system for a business. During the process of organizing existing tags, I developed this theoretical framework.
Switzerland of Northern Xinjiang: Kanas Trekking
I never expected my first outdoor trekking experience would be in Kanas.
Overview of Sorting Algorithms
Sorting algorithms are the most fundamental, widely applicable, and frequently tested algorithms in interviews. This article summarizes classic sorting algorithms: selection sort, insertion sort, …
PostgreSQL MongoFDW Installation and Deployment
Recently had business requirements to access MongoDB through PostgreSQL FDW, but compiling MongoDB FDW is really a nightmare.
Fundamentals of Information Theory: Entropy
Reading notes on 'Elements of Information Theory': What is entropy? Entropy is a measure of the uncertainty of random variables, and also a measure of the information needed to describe random …
Baiji 1509 Training Reflections
I once thought all day but learned nothing, which is not as good as what I learned in a moment. I came to Hangzhou to attend Alibaba's Baiji training to learn from seniors and improve my knowledge …
2014 Year-End Summary
Unable to sleep in the dead of night, spending the last hour of 2014 reviewing this year and looking ahead to next year seems quite appropriate.
On Computational Thinking
A paper for "History of Secrecy and Secrecy Systems" course, discussing computational thinking and its significance in undergraduate education, as well as methods for cultivating computational …
In Praise of Mathematics
What a wonderful subject mathematics is
Humans, Society, and Neural Networks
Neural networks emerged inspired by the human brain, so the operational mechanisms of human society also have various similarities and connections with neural network training. Some thoughts on …
2013 Year-End Summary
In the final half hour of 2013, reflecting on my experiences this year fills me with deep emotion.
Computer Networks and Logistics Systems
Computer networks are like a logistics system, with the only difference being that logistics systems transmit material entities like mail and packages, while computer networks transmit intangible …
Worldview, Values, and Life Philosophy
One inevitably traces back to questions about the world's origins, and answering these questions is the process of establishing one's cornerstone principles.
On the Hierarchy of Knowledge
Through observation and reflection, we can divide the mental process of deepening understanding from accepting knowledge to the highest level of 'enlightenment' into four stages: knowledge, …
Thinking Characteristics of Eastern and Western People
Eastern people emphasize macro-to-micro thinking, while Western people emphasize micro-to-macro thinking. In my view, this is the philosophical root of East-West thinking differences and many macro …
What Exactly Are Natural Numbers?
The concept of natural numbers should have been learned in elementary school. The foundation of all elementary mathematics begins with such a definition. However, when I entered university, I …
Fundamental Concepts of Linear Algebra
Connecting all concepts in linear algebra through one main thread
Views on Love
What ultimately determines romance and marriage?
Statistics Fundamentals: Descriptive Statistics
Statistical analysis is divided into two fields: descriptive statistics and inferential statistics. Descriptive Statistics is the technology for describing or characterizing existing data and is the most fundamental part of statistics. 1. Statistics …
Statistical analysis is divided into two fields: descriptive statistics and inferential statistics. Descriptive Statistics is the technology for describing or characterizing existing data and is the most fundamental part of statistics. 1. Statistics …
Inferential Statistics: The Past and Present of p-values
The core of inferential statistics lies in hypothesis testing. The basic logic is based on an important argument from philosophy of science: universal propositions can only be falsified, not proven. The reasoning is simple: individual cases cannot …
The core of inferential statistics lies in hypothesis testing. The basic logic is based on an important argument from philosophy of science: universal propositions can only be falsified, not proven. The reasoning is simple: individual cases cannot …
Building an ItemCF Recommender in Pure SQL
Everyone knows “item-based collaborative filtering” (ItemCF): Amazon recommendations, YouTube watch-next, etc. Here’s how to implement it in PostgreSQL using the MovieLens dataset. No Python, just SQL. Theory in one minute ItemCF recommends items …
Everyone knows “item-based collaborative filtering” (ItemCF): Amazon recommendations, YouTube watch-next, etc. Here’s how to implement it in PostgreSQL using the MovieLens dataset. No Python, just SQL. Theory in one minute ItemCF recommends items …
Basic Concepts of Probability Theory
1. Set Theory Sample space and sample points are undefined basic concepts in probability theory, like the concepts of points and lines in geometry. Definition: Event Event: An event is a set of sample points. $A=0$ means event A contains no sample …
1. Set Theory Sample space and sample points are undefined basic concepts in probability theory, like the concepts of points and lines in geometry. Definition: Event Event: An event is a set of sample points. $A=0$ means event A contains no sample …
Starting from /0: Understanding Errors and Exceptions
What happens when you divide by 0 in a computer? Errors are errors, exceptions are exceptions. The distinction here is quite subtle. Yes, no typo - the title uses /0 not 0. So the question arises: What happens when you divide by 0? Constraints are …
What happens when you divide by 0 in a computer? Errors are errors, exceptions are exceptions. The distinction here is quite subtle. Yes, no typo - the title uses /0 not 0. So the question arises: What happens when you divide by 0? Constraints are …
UUID Properties, Principles and Applications
A recent project needed to generate business transaction IDs with the following requirements: IDs must be generated in a distributed manner, cannot depend on central node allocation while ensuring global uniqueness. IDs must contain timestamps and …
A recent project needed to generate business transaction IDs with the following requirements: IDs must be generated in a distributed manner, cannot depend on central node allocation while ensuring global uniqueness. IDs must contain timestamps and …
Tag Classification Theory
Recently, I needed to design a tag management system for a business. During the process of organizing existing tags, I developed this theoretical framework. 0. Tag Definition: Tag Taxonomy For tags, it’s difficult to provide a universally accepted …
Recently, I needed to design a tag management system for a business. During the process of organizing existing tags, I developed this theoretical framework. 0. Tag Definition: Tag Taxonomy For tags, it’s difficult to provide a universally accepted …
Switzerland of Northern Xinjiang: Kanas Trekking
I never expected my first outdoor trekking experience would be in Kanas. Kanas Route Jiadengyu - Hemu - Black Lake - Kanas - Baihaba Starting from Jiadengyu, head east along the cement road - that’s the route that doesn’t go through the scenic area. …
I never expected my first outdoor trekking experience would be in Kanas. Kanas Route Jiadengyu - Hemu - Black Lake - Kanas - Baihaba Starting from Jiadengyu, head east along the cement road - that’s the route that doesn’t go through the scenic area. …
Overview of Sorting Algorithms
Sorting algorithms are the most fundamental, widely applicable, and frequently tested algorithms in interviews. A sorting algorithm is an algorithm that can arrange a string of data in a specific order. Where: Output result is an ascending sequence …
Sorting algorithms are the most fundamental, widely applicable, and frequently tested algorithms in interviews. A sorting algorithm is an algorithm that can arrange a string of data in a specific order. Where: Output result is an ascending sequence …
PostgreSQL MongoFDW Installation and Deployment
Update: Recently MongoFDW has been taken over by Cybertech for maintenance, so maybe it’s not as bad anymore. Recently had business requirements to access MongoDB through PostgreSQL FDW. Initially I thought this was a pretty easy task. But what …
Update: Recently MongoFDW has been taken over by Cybertech for maintenance, so maybe it’s not as bad anymore. Recently had business requirements to access MongoDB through PostgreSQL FDW. Initially I thought this was a pretty easy task. But what …
Fundamentals of Information Theory: Entropy
Information theory answers two fundamental questions in communication theory: The critical value for data compression: entropy HHH The critical value for communication transmission rate: channel capacity CCC But information theory’s content extends …
Information theory answers two fundamental questions in communication theory: The critical value for data compression: entropy HHH The critical value for communication transmission rate: channel capacity CCC But information theory’s content extends …
Baiji 1509 Training Reflections
On September 23rd, I came to Hangzhou to attend Baiji training. Unlike Bai’a, I didn’t have special expectations for Baiji beforehand. After all, for a one-day training, it might just be going through the motions, and I was skeptical about how much I …
On September 23rd, I came to Hangzhou to attend Baiji training. Unlike Bai’a, I didn’t have special expectations for Baiji beforehand. After all, for a one-day training, it might just be going through the motions, and I was skeptical about how much I …
2014 Year-End Summary
Unable to sleep in the dead of night, spending the last hour of 2014 reviewing this year and looking ahead to next year seems quite appropriate. Casually flipping through my 2013 year-end summary and 2014 diary entries, I’m filled with many emotions. …
Unable to sleep in the dead of night, spending the last hour of 2014 reviewing this year and looking ahead to next year seems quite appropriate. Casually flipping through my 2013 year-end summary and 2014 diary entries, I’m filled with many emotions. …
On Computational Thinking
A paper for “History of Secrecy and Secrecy Systems” course, discussing computational thinking and its significance in undergraduate education. I guess this was the teacher’s own assignment. 1. Abstract This paper discusses related content on …
A paper for “History of Secrecy and Secrecy Systems” course, discussing computational thinking and its significance in undergraduate education. I guess this was the teacher’s own assignment. 1. Abstract This paper discusses related content on …
In Praise of Mathematics
In the very center of humanity’s rational world An eternal ivory tower stands tall upon it From the depths of the vast intuitive earth below Rising straight to the vicinity of the chaotic heavens where dense clouds roll Countless electric branches …
In the very center of humanity’s rational world An eternal ivory tower stands tall upon it From the depths of the vast intuitive earth below Rising straight to the vicinity of the chaotic heavens where dense clouds roll Countless electric branches …
Humans, Society, and Neural Networks
Neural networks emerged inspired by the human brain, so the operational mechanisms of human society also have various similarities and connections with neural network training. This year, I dabbled in many other disciplines. Most were superficial …
Neural networks emerged inspired by the human brain, so the operational mechanisms of human society also have various similarities and connections with neural network training. This year, I dabbled in many other disciplines. Most were superficial …
2013 Year-End Summary
In the final half hour of 2013, reflecting on my experiences this year fills me with deep emotion. In 2013, I proved many things. From a typical underperformer to achieving excellence in all professional courses with perfect grades and earning praise …
In the final half hour of 2013, reflecting on my experiences this year fills me with deep emotion. In 2013, I proved many things. From a typical underperformer to achieving excellence in all professional courses with perfect grades and earning praise …
Computer Networks and Logistics Systems
Computer networks are like a logistics system, with the difference being that logistics systems transmit material entities like mail and packages, while computer networks transmit intangible information. Computer networks are divided into five layers …
Computer networks are like a logistics system, with the difference being that logistics systems transmit material entities like mail and packages, while computer networks transmit intangible information. Computer networks are divided into five layers …
Worldview, Values, and Life Philosophy
One inevitably traces back to questions about the world’s origins, and answering these questions is the process of establishing one’s cornerstone principles. Perhaps because I recently resolved a psychological issue that had troubled me for nearly …
One inevitably traces back to questions about the world’s origins, and answering these questions is the process of establishing one’s cornerstone principles. Perhaps because I recently resolved a psychological issue that had troubled me for nearly …
On the Hierarchy of Knowledge
Through observation and reflection, we can divide the mental process of deepening understanding from accepting knowledge to the highest level of “enlightenment” into four stages: knowledge, understanding, consciousness, and enlightenment. The overall …
Through observation and reflection, we can divide the mental process of deepening understanding from accepting knowledge to the highest level of “enlightenment” into four stages: knowledge, understanding, consciousness, and enlightenment. The overall …
Thinking Characteristics of Eastern and Western People
Eastern people emphasize macro-to-micro thinking, while Western people emphasize micro-to-macro thinking. In my view, this is the root of East-West thinking differences. First, we need to clarify the definition of East and West. Here, “East” refers …
Eastern people emphasize macro-to-micro thinking, while Western people emphasize micro-to-macro thinking. In my view, this is the root of East-West thinking differences. First, we need to clarify the definition of East and West. Here, “East” refers …
What Exactly Are Natural Numbers?
The concept of natural numbers should have been learned in elementary school. The foundation of all elementary mathematics begins with such a definition. However, when I entered university, I encountered this question again in discrete mathematics. …
The concept of natural numbers should have been learned in elementary school. The foundation of all elementary mathematics begins with such a definition. However, when I entered university, I encountered this question again in discrete mathematics. …
Fundamental Concepts of Linear Algebra
Connecting all concepts in linear algebra through one main thread Vectors There are three perspectives on vectors: Physics perspective: A vector is an arrow with direction and magnitude Computer perspective: A vector is an ordered list Mathematical …
Connecting all concepts in linear algebra through one main thread Vectors There are three perspectives on vectors: Physics perspective: A vector is an arrow with direction and magnitude Computer perspective: A vector is an ordered list Mathematical …
Views on Love
Recently, my roommate broke up with his girlfriend. What was once a lovey-dovey, inseparable couple suddenly separated just like that. This inevitably made me start thinking about some questions I hadn’t carefully considered before: What ultimately …
Recently, my roommate broke up with his girlfriend. What was once a lovey-dovey, inseparable couple suddenly separated just like that. This inevitably made me start thinking about some questions I hadn’t carefully considered before: What ultimately …