Postgres

My first Chinese book

My first Chinese book has been published on 1st June.


How to calculate A * B mod N, where numbers are 64 bit integers

I made a program to calculate ‘A * B mod N’, where A, B and N are 64 bit integers.

Main problem is to avoid overflow when calculate ‘A * B’.

I searched a while and finally decided to use the interleaved modular multiplication method, which is used in the feild of electric circuit design.

I found some bugs when I tested corner cases, so I have to fix them [2018.9.2]. I think I’ve fixed them [2018.9.3]. I’ve just improved it! [2018.9.5]

The program is shown below:


postgres cluster management system in GoCardless

I found an interesting postgres cluster management system using Pacemaker. It is created by GoCardless. They provide a vagrant box, so we can play and learn it easily.


When should I do VACUUM FULL?

There is unfortunately no best practice when you should execute “VACUUM FULL”. The extension pg_freespacemap however gives you suggestion.


Customized Statistics Views in PostgreSQL

I always use my customized statistics views shown below because the original ones provide only minimum information.

I show my tools in this post.


Difference between PostgreSQL and MySQL: (1) Replication

Many people around the world admire the Uber’s article “Why Uber Engineering Switched from Postgres to MySQL”, but I think this article contains many mistakes. So, I’m going to provide correct information regarding to PostgreSQL and MySQL.

In this post, I explain the replication of both databases.


Testing PostgresPro's pg_arman with ptrack

In this week end, I tested PostgresPro’s pg_arman with ptrack. Speaking from the conclusion, it works well.


Multi-GTM for Postgres XC

Five years ago, I was interested in Postgres-XC , currenty called Postgres-X2, and made a multi-GTM (global transaction manager) system for it.

Though I had forgotten this work for a long time, I found its executable files from my old PC a month ago (unfortunately the source code of them was lost). They perfectly run, so I provide a Vagrant box to run my old program on your PC.


How to relocate tablespace directory

I’ll demonstrate how to relocate a tablespace directory without the reconstruction of databases.


New WAL format in PostgreSQL 9.5

This post is a part of my document.

The XLOG data format has changed in version 9.5.