SoFunction
Updated on 2025-03-09

The difference and description of Postgresql and mysql

PostgreSQL and MySQL are two popular relational database management systems (RDBMSs) with their respective features and advantages.

Although both databases can handle large amounts of data, there will be some differences in different situations.

The following will focus on the difference between PostgreSQL and MySQL, with case descriptions.

1. Architectural design

In terms of architecture design, PostgreSQL and MySQL are different.

PostgreSQL is designed based on an object-oriented architecture, and can implement more advanced data models through object inheritance, polymorphism and inheritance mechanisms.

MySQL, on the other hand, pays more attention to performance and flexibility.

For example, in implementing an O2o e-commerce system, it is necessary to add delivery address information (address_info) to the user information table (user_info).

In PostgreSQL, address information can be stored in a separate table (address) through object-oriented inheritance mechanism, and addresses can be bound to user information table in the form of a composite type.

In MySQL, address information needs to be added to the user information table, which will make the user information table larger and more difficult to maintain.

2. Data type and query language

Another important difference is the data types and query languages ​​supported by the database.

PostgreSQL has richer data type support, including arrays, enums, dates and times, and also supports advanced query languages ​​such as JSON queries and XML queries.

In addition, PostgreSQL also supports Covering Index, which is an advanced index type that supports faster queries, which can effectively speed up query performance.

For example, in the field of advertising technology, to identify which web pages the advertisement should be displayed through the advertising search process, it is necessary to query a large amount of advertising information and the paired web page information.

In PostgreSQL, advertising information and web page information can be stored in different tables and queryed using indexes.

In MySQL, if you need to conduct joint queries between different tables at the same time, you need to use union and subqueries, which may also lead to performance degradation.

In addition, if you need to query a large amount of JSON data, PostgreSQL performance is even better.

3. Data integrity and fault tolerance

The third difference lies in the integrity and fault tolerance of the data. PostgreSQL has strong protection of data integrity and supports foreign key constraints between tables to ensure data integrity.

PostgreSQL rejects the action if you try to delete the table without removing its foreign key reference.

MySQL does not have such a default setting. Before deleting the table, it is necessary to manually perform foreign key constraint checking operations, which will increase the difficulty of the operation.

In addition, the performance of the two databases is also different in terms of fault tolerance and data recovery.

PostgreSQL supports Disaster Recovery, which can automatically complete data recovery, while MySQL needs to be operated manually.

For example, in an online payment application, if an interrupt occurs while executing a transaction, PostgreSQL can automatically restore the state of transmission fallback to ensure data integrity.

In MySQL, manual data recovery is required, which increases the risk of timeliness and security.

Differences in statements

1. Declaration of data type and length

In PostgreSQL, you can declare the data type and length of a column as shown below:

CREATE TABLE tablename (
    id SERIAL PRIMARY KEY,
    name VARCHAR(50),
    age INTEGER
);

In the above code, the length of the name column of type VARCHAR is 50, while the length of the age column of type INT is not required.

In MySQL, the VARCHAR type name column needs to indicate the length.

As shown below:

CREATE TABLE tablename (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(50),
    age INT
);

In the above code, the length of the name column of VARCHAR type is also 50, but the difference between the age column of INT type and PostgreSQL, the length needs to be indicated.

2. Quotation marks of strings

In PostgreSQL, single and double quotes are used interchangeably and strings can be wrapped with $ symbols.

As shown below:

SELECT * FROM tablename WHERE name = 'John';
SELECT * FROM tablename WHERE name = "John";
SELECT * FROM tablename WHERE name = $1;

In the above code, $1 in PostgreSQL represents a placeholder in a parameterized query, which can prevent SQL injection attacks.

In MySQL, only single quotes can be used, and double quotes are regarded as glyphs.

As shown below:

SELECT * FROM tablename WHERE name = 'John';

3. Statement of the Self-Growth Column

In PostgreSQL, you can use the SERIAL type to declare a self-growth column.

As shown below:

CREATE TABLE tablename (
    id SERIAL PRIMARY KEY,
    name VARCHAR(50)
);

In MySQL, you can use the AUTO_INCREMENT keyword to declare a self-growth column.

As shown below:

CREATE TABLE tablename (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(50)
);

Summarize

PostgreSQL and MySQL are two different relational database management systems that differ in architecture design, data type and query language, data integrity and fault tolerance.

If you need to deal with complex data types, need to do advanced index queries, or involve a lot of JSON data, then using PostgreSQL may be better.

And if you need a database that is fast and has excellent performance, it is relatively more appropriate to use MySQL. However, the best choice often depends on your specific needs and application scenarios.

The above is personal experience. I hope you can give you a reference and I hope you can support me more.