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MySQL 8.0 Reference Manual  /  ...  /  Point-in-Time Recovery Using Binary Log

7.5.1 Point-in-Time Recovery Using Binary Log

This section explains the general idea of using the binary log to perform a point-in-time-recovery. The next section, Section 7.5.2, “Point-in-Time Recovery Using Event Positions”, explains the operation in details with an example.

Note

Many of the examples in this and the next section use the mysql client to process binary log output produced by mysqlbinlog. If your binary log contains \0 (null) characters, that output cannot be parsed by mysql unless you invoke it with the --binary-mode option.

The source of information for point-in-time recovery is the set of binary log files generated subsequent to the full backup operation. Therefore, to allow a server to be restored to a point-in-time, binary logging must be enabled on it, which is the default setting for MySQL 8.0 (see Section 5.4.4, “The Binary Log”).

To restore data from the binary log, you must know the name and location of the current binary log files. By default, the server creates binary log files in the data directory, but a path name can be specified with the --log-bin option to place the files in a different location. To see a listing of all binary log files, use this statement:

mysql> SHOW BINARY LOGS;

To determine the name of the current binary log file, issue the following statement:

mysql> SHOW MASTER STATUS;

The mysqlbinlog utility converts the events in the binary log files from binary format to text so that they can be viewed or applied. mysqlbinlog has options for selecting sections of the binary log based on event times or position of events within the log. See Section 4.6.8, “mysqlbinlog — Utility for Processing Binary Log Files”.

Applying events from the binary log causes the data modifications they represent to be reexecuted. This enables recovery of data changes for a given span of time. To apply events from the binary log, process mysqlbinlog output using the mysql client:

shell> mysqlbinlog binlog_files | mysql -u root -p

If binary log files have been encrypted, which can be done from MySQL 8.0.14 onwards, mysqlbinlog cannot read them directly as in the above example, but can read them from the server using the --read-from-remote-server (-R) option. For example:

shell> mysqlbinlog --read-from-remote-server --host=host_name --port=3306  --user=root --password --ssl-mode=required  binlog_files | mysql -u root -p

Here, the option --ssl-mode=required has been used to ensure that the data from the binary log files is protected in transit, because it is sent to mysqlbinlog in an unencrypted format.

Viewing log contents can be useful when you need to determine event times or positions to select partial log contents prior to executing events. To view events from the log, send mysqlbinlog output into a paging program:

shell> mysqlbinlog binlog_files | more

Alternatively, save the output in a file and view the file in a text editor:

shell> mysqlbinlog binlog_files > tmpfile
shell> ... edit tmpfile ...

Saving the output in a file is useful as a preliminary to executing the log contents with certain events removed, such as an accidental DROP TABLE. You can delete from the file any statements not to be executed before executing its contents. After editing the file, apply the contents as follows:

shell> mysql -u root -p < tmpfile

If you have more than one binary log to apply on the MySQL server, the safe method is to process them all using a single connection to the server. Here is an example that demonstrates what may be unsafe:

shell> mysqlbinlog binlog.000001 | mysql -u root -p # DANGER!!
shell> mysqlbinlog binlog.000002 | mysql -u root -p # DANGER!!

Processing binary logs this way using different connections to the server causes problems if the first log file contains a CREATE TEMPORARY TABLE statement and the second log contains a statement that uses the temporary table. When the first mysql process terminates, the server drops the temporary table. When the second mysql process attempts to use the table, the server reports unknown table.

To avoid problems like this, use a single connection to apply the contents of all binary log files that you want to process. Here is one way to do so:

shell> mysqlbinlog binlog.000001 binlog.000002 | mysql -u root -p

Another approach is to write the whole log to a single file and then process the file:

shell> mysqlbinlog binlog.000001 >  /tmp/statements.sql
shell> mysqlbinlog binlog.000002 >> /tmp/statements.sql
shell> mysql -u root -p -e "source /tmp/statements.sql"

When writing to a dump file while reading back from a binary log containing GTIDs (see Section 17.1.3, “Replication with Global Transaction Identifiers”), use the --skip-gtids option with mysqlbinlog, like this:

shell> mysqlbinlog --skip-gtids binlog.000001 >  /tmp/dump.sql
shell> mysqlbinlog --skip-gtids binlog.000002 >> /tmp/dump.sql
shell> mysql -u root -p -e "source /tmp/dump.sql"