What is a database backup?

#Database backup refers to backing up the database to prevent loss. There are four types of backups in the database that can be applied to different scenarios.

1. Full backup

This is the method commonly used by most people. It can back up the entire database, including user tables, system tables, indexes, and views. and stored procedures and other database objects. But it takes more time and space, so it is generally recommended to do a full backup once a week.

2. Transaction log backup

The transaction log is a separate file that records changes to the database. When backing up, you only need to copy the changes to the database since the last backup. The changes are made so it takes very little time. To make the database robust, hourly or even more frequent backups of the transaction log are recommended.

3. Differential backup

is also called incremental backup. It is another method of backing up only part of the database. It does not use the transaction log. Instead, it uses a new image of the entire database. It is smaller than the original full backup because it only contains the database that has changed since the last full backup. Its advantage is fast storage and recovery speed. It is recommended to do a differential backup every day.

4. File backup

The database can be composed of many files on the hard disk. If the database is very large and you cannot back it up in one night, you can use file backup to back up a portion of the database every night. Since the database is generally not large enough to require multiple file storage, this type of backup is not very common.

In MySQL, our backup data can be divided into three types:

1. Cold backup means that when the database is backed up, the database cannot perform read and write operations, that is, The database is going offline

2. Hot backup means that when the database is backed up, the read and write operations of the database are not affected

3. Warm backup means that when the database is backed up , The read operation of the database can be performed, but the write operation cannot be performed

After considering the running status of the database when backing up the data, we also need to consider the backup method of the data in the MySQL database

Physical backup generally uses tar, cp and other commands to directly package and copy the data files of the database to achieve the backup effect

Logical backup generally means exporting data from the database through specific tools and saving the backup separately (logical backup will lose data accuracy) .

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