Database Backup and Recovery: MySQL vs. PostgreSQL

Database backup and recovery: MySQL vs. PostgreSQL

Introduction:
Database backup and recovery is a vital part of database management. During the database operation and maintenance process, we need to regularly back up the database to deal with emergencies and be able to quickly restore data to ensure business continuity. This article will focus on comparing the different backup and recovery strategies of two common relational database management systems (DBMS): MySQL and PostgreSQL, and provide corresponding code examples.

1. MySQL
MySQL is a widely used open source relational database management system. In MySQL, we can use multiple methods for backup and recovery.

1. Backup
   (1) Logical backup
   Logical backup refers to exporting the logical structure of the database into a logical file, for example, using the mysqldump tool to export data into a SQL script. The following is an example:

mysqldump -u 用户名 -p 密码 数据库名 > 备份文件名.sql

(2) Physical backup
Physical backup is a direct backup of binary files of the database, including data files and log files. We can use MySQL's own tool mysqlpump to perform physical backup. The following is an example:

mysqlpump -u 用户名 -p 密码 --default-character-set=utf8 数据库名 --result-file=备份文件名.sql

2. Recovery
   (1) Logical recovery
   Logical recovery restores the database by executing the SQL script in the backup file. The following is an example:

mysql -u 用户名 -p 密码 数据库名 < 备份文件名.sql

(2) Physical recovery
Physical recovery is performed by copying the backed-up binary files directly to the MySQL data directory. The following is an example:

停止MySQL服务
复制备份的二进制文件到数据目录下对应的位置
启动MySQL服务

2. PostgreSQL
PostgreSQL is a powerful open source object-relational database management system. In PostgreSQL, we can also use multiple methods for backup and recovery.

1. Backup
   (1) Logical backup
   Logical backup is to export the database into a logical file by using the pg_dump tool. The following is an example:

pg_dump -U 用户名 -f 备份文件名.sql 数据库名

(2) Physical backup
Physical backup is a direct backup of the data files and WAL (Write Ahead Log) files of the database. We can use the pg_basebackup tool to perform physical backup. The following is an example:

First, create a basic backup on the PostgreSQL master server:

pg_basebackup -h 主服务器地址 -D 备份目录 -Fp -Xs -P

Then, in the backup directory, create a recovery configuration file recovery.conf for recovery, And set standby_mode to 'on':

echo "standby_mode = 'on'" >> 备份目录/recovery.conf

2. Recovery
   (1) Logical recovery
   Logical recovery restores the database by executing the SQL script in the backup file. The following is an example:

psql -U 用户名 -d 数据库名 -f 备份文件名.sql

(2) Physical recovery
Physical recovery is performed by copying the backed-up data files and WAL files to the PostgreSQL data directory. The following is an example:

First, stop the PostgreSQL service on the backup server and copy the backup file to the corresponding location in the data directory.

Then, on the recovery server, create a recovery configuration file recovery.conf and set primary_conninfo to point to the primary server:

echo "primary_conninfo = 'host=主服务器地址 port=主服务器端口 user=用户名 password=密码'" >> 数据目录/recovery.conf

Finally, start the PostgreSQL service.

Conclusion:
Through the above comparison of MySQL and PostgreSQL in terms of backup and recovery, we can see that they have slightly different methods, but they can essentially meet the needs of database backup and recovery. Which method to use depends mainly on the actual application scenario and personal preference. No matter which method you choose, regular backups and test restores are important steps to ensure data security and business continuity.

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