Multi-dimensional comparison between PostgreSQL and MySQL

0. Preface

In today's world of software development and data management, databases are one of the critical infrastructures. Choosing the right database management system (DBMS) is critical to application performance, scalability, and data integrity. In this blog, we will make a multi-dimensional comparison of two widely used relational database systems: PostgreSQL and MySQL.

PostgreSQL and MySQL are two open source relational database management systems, they have a huge user base and active development community. Although both are relational databases, they have some differences in functions, performance, scalability, and applicable scenarios.

In this article, we will discuss the comparison of the following 20 aspects. There may be some omissions in the description, and we will try to cover them as much as possible.

1. Data Integrity and Consistency
2. Functions and Features
3. performance and scalability
4. availability and stability
5. Open source community support
6. Replication and high availability
7. safety
8. JSON support
9. Full text search function
10. Geospatial Data Processing
11. Query Performance Tuning Options
12. foreign key constraints
13. Multiversion Concurrency Control (MVCC)
14. storage engine
15. Partition Table
16. large data capacity
17. Data backup and recovery
18. Data Analysis and Reporting Functions
19. database management tool
20. platform compatibility

By comparing these aspects, readers will be able to more clearly understand and compare the advantages and disadvantages of PostgreSQL and MySQL in different aspects. This will help developers, data engineers, and policy makers make informed decisions when selecting a database management system for their specific needs.

In the following blogs, we will detail each of the contrasting aspects and provide examples and guidance on how to implement the relevant functionality in PostgreSQL and MySQL. Whether you are interested in these two database systems or need more information when deciding which database system to use in your project, this blog will provide you with valuable insights and guidance.

I'm here to start, so you can go ahead and delve into the PostgreSQL vs MySQL comparison so you can make an informed choice and get the best database support and performance for your application.

1. Basic comparison

aspect	PostgreSQL	MySQL
1. Data Integrity and Consistency	Supports ACID transactions and rich constraints	Supports ACID transactions, but with relatively few constraints
2. Functions and Features	Complex query syntax, advanced data types, triggers, and more	Basic query syntax, less advanced features
3. Performance and scalability	Powerful query optimizer , horizontal and vertical scaling options	Suitable for handling a large number of simple queries, relatively weak complex queries
4. Availability and Stability	Long-term stable version release and maintenance plan	Long-term stable version release and maintenance plan
5. Open source community support	Huge global developer community , active open source ecosystem	Huge open source community with many third-party tools and libraries available
6. Replication and high availability	Supports streaming and logical replication with multiple high availability options	Support master-slave replication and semi-synchronous replication
7. Security	Strong authentication and authorization mechanism, support SSL encrypted connection	Authentication and authorization mechanisms are relatively simple
8. JSON support	Built-in support for JSON data type and JSON functions	JSON data type and functions are supported starting from MySQL 5.7
9. Full text search function	Built-in full-text search function, supporting multiple search algorithms	Requires a full-text search plugin or third-party tool
10. Geospatial Data Processing	Built-in support for geospatial data types and functions	Requires the use of GIS extensions or third-party libraries
11. Query Performance Tuning Options	Provides rich query optimization options and statistics	Relatively few query optimization options
12. Foreign key constraints	Supports foreign key constraints and cascading operations to ensure data integrity and consistency	Supports foreign key constraints, but cascading operations are relatively limited
13. Multiversion Concurrency Control (MVCC)	Use MVCC to provide high concurrent performance and data consistency	Using lock mechanism to achieve concurrency control
14. Storage Engine	By default, PostgreSQL's own storage engine is used , and third-party storage engines such as PostgreSQL Foreign Data Wrapper are also supported	The InnoDB storage engine is used by default , and other storage engines such as MyISAM are also supported
15. Partition table	Supports table partitioning to improve query performance and data management	Partition tables are supported , but the functions are relatively limited
16. Large data capacity	Support large object (LOB) and table space , suitable for storing large-capacity data	Large objects (LOBs) are supported, but table space management is relatively simple
17. Data Backup and Restoration	Supports point-in-time recovery and logical backup for fine-grained recovery control	Support backup and recovery mechanism based on binary log, less logical backup options
18. Data analysis and report function	Provides advanced analysis functions such as window functions and pivot tables	Provides basic aggregation functions and grouping functions, less advanced analysis options
19. Database management tools	Provide powerful graphical management tools such as pgAdmin	Provide graphical management tools such as MySQL Workbench
20. Platform Compatibility	Runs on multiple operating systems including Linux, Windows, macOS, and more	Runs on multiple operating systems including Linux, Windows, macOS, and more

2. Grammar comparison between PostgreSQL and MySQL

Function	PostgreSQL	MySQL	difference	example
create database	CREATE DATABASE dbname;	CREATE DATABASE dbname;	No difference	CREATE DATABASE mydb;
delete database	DROP DATABASE dbname;	DROP DATABASE dbname;	No difference	DROP DATABASE mydb;
connect to database	\c dbname;	USE dbname;	No difference	\c mydb;
create table	CREATE TABLE tablename (…);	CREATE TABLE tablename (…);	No difference	CREATE TABLE employees (id INT, name VARCHAR(50), age INT);
delete table	DROP TABLE tablename;	DROP TABLE tablename;	No difference	DROP TABLE employees;
insert data	INSERT INTO tablename VALUES ();	INSERT INTO tablename VALUES ();	No difference	INSERT INTO employees VALUES (1, ‘John Doe’, 25);
update data	UPDATE tablename SET …;	UPDATE tablename SET …;	No difference	UPDATE employees SET age = 30 WHERE id = 1;
delete data	DELETE FROM tablename WHERE …;	DELETE FROM tablename WHERE …;	No difference	DELETE FROM employees WHERE age > 30;
Query data	SELECT * FROM tablename;	SELECT * FROM tablename;	No difference	SELECT * FROM employees;
Sort data	SELECT * FROM tablename ORDER BY …;	SELECT * FROM tablename ORDER BY …;	No difference	SELECT * FROM employees ORDER BY age DESC;
连接表	SELECT * FROM table1 JOIN table2 ON …;	SELECT * FROM table1 JOIN table2 ON …;	无差异	SELECT * FROM employees JOIN departments ON employees.department_id = departments.id;
聚合函数	COUNT(), AVG(), SUM(), …	COUNT(), AVG(), SUM(), …	无差异	SELECT COUNT(*) FROM employees;
字符串拼接	使用 CONCAT() 函数	使用 CONCAT() 函数或者 [		](https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#operator_concat) 运算符
子字符串	使用 SUBSTRING() 函数	使用 SUBSTRING() 或 SUBSTR() 函数	有差异	SELECT SUBSTRING(name, 1, 3) AS initials FROM employees;
获取当前日期和时间	CURRENT_DATE，CURRENT_TIME	CURDATE()，CURTIME()	有差异	SELECT CURRENT_DATE;

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3. 特性

1. WITH RECURSIVE:
   • 场景：处理层次结构数据，如组织架构、树形结构等。
   • 示例：

WITH RECURSIVE recursive_cte AS (
   SELECT id, name, parent_id
   FROM categories
   WHERE id = 1
   UNION ALL
   SELECT c.id, c.name, c.parent_id
   FROM categories c
   INNER JOIN recursive_cte rc ON c.parent_id = rc.id
)
SELECT * FROM recursive_cte;

2. LATERAL JOIN:
   • 场景：在查询中进行关联计算，例如在主查询的每一行上执行子查询并将结果与主查询进行关联。
   • 示例：

SELECT t1.id, t2.avg_value
FROM table1 t1
LEFT JOIN LATERAL (
   SELECT AVG(value) AS avg_value
   FROM table2 t2
   WHERE t2.id = t1.id
) t2 ON true;

3. WITH ORDINALITY:
   • 场景：与 UNNEST 结合使用，为数组的每个元素添加一个序号。
   • 示例：

SELECT *
FROM unnest(ARRAY['apple', 'banana', 'orange']) WITH ORDINALITY AS t(fruit, index);

4. RETURNING:
   • 场景：在 INSERT、UPDATE 或 DELETE 操作中，返回受影响的行或特定列的结果。
   • 示例：

INSERT INTO employees (name, salary)
VALUES ('John Doe', 5000)
RETURNING id, name, salary;

特有函数和场景：

1. jsonb_agg:
   • 场景：将行集合聚合为 JSONB 数组。
   • 示例：

SELECT category, jsonb_agg(product) AS products
FROM products
GROUP BY category;

2. array_to_string:
   • 场景：将数组元素连接为单个字符串。
   • 示例：

SELECT array_to_string(array[1, 2, 3], ',') AS result;
-- 输出: "1,2,3"

3. tsvector:
   • 场景：进行全文搜索和匹配操作。
   • 示例：

SELECT to_tsvector('english', 'The quick brown fox') AS vector;
-- 输出: 'brown':3 'fox':4 'quick':2

4. ST_DWithin:
   • 场景：检查两个地理对象之间的距离是否在指定范围内。
   • 示例：

SELECT *
FROM locations
WHERE ST_DWithin(point1, point2, 100);

5. generate_series:
   • 场景：生成一个连续的整数序列。
   • 示例：

SELECT *
FROM generate_series(1, 10) AS num;

6. regexp_matches:
   • 场景：通过正则表达式从文本中提取匹配的内容。
   • 示例：

SELECT regexp_matches('Hello, world!', '[a-z]+', 'gi');
-- 输出: {hello,world}

7. pg_stat_get_progress_info:
   • 场景：获取后台进程的执行进度信息（例如，复制、索引创建等）。
   • 示例：

SELECT * FROM pg_stat_get_progress_info(123);
-- 其中 123 是后台进程的进程 ID

8. pg_stat_statements:
   • 场景：跟踪 SQL 语句的执行统计信息，包括执行次数、总运行时间等。
   • 示例：

SELECT query, calls, total_time
FROM pg_stat_statements
WHERE userid = 1
ORDER BY total_time DESC
LIMIT 10;

4. 参考文档

1. Official PostgreSQL documentation : The official documentation of PostgreSQL provides comprehensive references and guides, covering all aspects of functions and usage.

2. MySQL official documentation : MySQL's official documentation contains detailed references and instructions, covering the functions and usage of various MySQL versions.

3. Comparison of PostgreSQL and MySQL : A functional matrix provided on the official PostgreSQL website to compare the functions and features of PostgreSQL and MySQL in different aspects.

4. PostgreSQL vs. MySQL: Which is Better for Your Project? : This tutorial introduces the factors to consider when using PostgreSQL and MySQL, and provides the advantages and disadvantages of comparing the two to help you choose the right database for your project.