How to implement differential backup of database backup in PHP

As the amount of data continues to increase, database backup becomes more important. Regular backup of the database can ensure data security, but traditional full backup takes up a lot of storage space and takes a long time to backup. How to implement differential backup has become a problem that needs to be solved during the backup process. In PHP applications, the way to implement differential backup of database backup is to use incremental backup and differential backup.

The principle of incremental backup is to back up only changed data. First perform a full backup, and then only back up data that has changed since the full backup at each backup. When the amount of data increases, backup will only back up the newly added data. The amount of backup data can be greatly reduced, reducing the cost of backup time and space.

Differential backup is to back up the changed data between a certain point in time and the last backup time point. Differential backup only backs up the difference between two points in time. Compared with full backup, differential backup can back up data content faster and use storage space more effectively. Differential backup also helps a single backup not be too large, making recovery and management easier.

As an Internet back-end language, PHP itself does not support the database backup function, but PHP provides some database operation interfaces and functions through which the database backup function can be realized. The following is how PHP implements differential backup of database backup:

1. Incremental backup

In PHP, incremental backup can be achieved in two ways:

1.1 Using MySQL's binlog

MySQL provides binlog to record database operation records, including operations such as additions, deletions, modifications, and queries. Incremental backup can be achieved by reading binlog using PHP. The steps are as follows:

1) Turn on binlog and add the following information to the MySQL configuration file my.cnf:

[mysqld]
log-bin=mysql-bin

This operation will turn on binlog and store the binlog in the data directory of the MySQL installation path. Down.

2) Connect to the MySQL database in PHP, and then perform the following operations:

$conn = mysqli_connect('host', 'user', 'password');
$rs = mysqli_query($conn,"SHOW MASTER STATUS");
$row = mysqli_fetch_array($rs);
$filename = $row['File'];
$position = $row['Position'];
$mysqlbinlog = 'mysqlbinlog -u root -p$pass --base64-output=decode-rows ';
$cmd = $mysqlbinlog.' '.$filename.' --start-position='.$position;
$data = shell_exec($cmd);

The reading operation here is implemented through the system function and shell command, and the read data is binlog data. From this binlog data, we can analyze the modifications since the last backup.

1.2 Using timestamps

This method is relatively simple. The steps are as follows:

1) When backing up the database, record the timestamp at the time of backup.

2) Take out the timestamp of the last backup before backing up, and compare the data between the two timestamps for backup.

3) Update timestamp after backup.

This method requires some recording and storage before and after the backup, and it is also more troublesome to process.

2. Differential backup

The common method of differential backup is to record the timestamp of the backup based on the full backup, and then take out the timestamp of the previous backup during each backup, and compare the two Data between timestamps is backed up. The operation steps are as follows:

1) When performing a full backup, record the backup timestamp at the same time.

2) When backing up differences, query the new and updated data after the last backup timestamp and back it up.

3) Update the backup timestamp after backup.

When implementing differential backup, you can also record all update and delete operations based on MySQL's binlog. Based on the operation records, the changed data of each table can be calculated and backed up.

The two backup methods provided in this article, incremental backup and differential backup, can both achieve the goal, but their respective applicable situations are different. If data updates are frequent, incremental backup is a more appropriate method. On the contrary, if data updates are less frequent, differential backup should be selected. In actual applications, it is necessary to make judgments based on the actual situation and choose a more appropriate backup method.

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