Locking Tables for Read in mysqldump

The mysqldump command in MySQL is used to create backups of databases. One of the options available is -l, --lock-tables, which ensures tables are locked with a read lock before dumping data. This prevents changes to the tables during the dump process, ensuring data consistency.

For example, to create a dump of a database named mydatabase with tables locked for read:

mysqldump -l mydatabase > mydatabase_backup.sql

This command locks all tables in mydatabase and stores the dump in mydatabase_backup.sql.

To verify if tables are locked during the dump, you can check the process list in MySQL while the dump is in progress:

SHOW PROCESSLIST;

You should see a process related to the dump with state Waiting for table level lock.

Another use case is when you want to dump only specific tables while locking them:

mysqldump -l mydatabase table1 table2 > specific_tables_backup.sql

This command locks table1 and table2 in mydatabase and saves the dump in specific_tables_backup.sql.

If you need to dump a database and compress the output, you can combine the lock tables option with gzip compression:

mysqldump -l mydatabase | gzip > mydatabase_backup.sql.gz

This command locks all tables in mydatabase and compresses the dump using gzip, saving it as mydatabase_backup.sql.gz.

To include SQL statements for creating and dropping tables, in addition to data, you can use the --add-drop-table option along with -l:

mysqldump -l --add-drop-table mydatabase > mydatabase_with_structure.sql

This command locks all tables in mydatabase, includes drop table statements, and saves the dump as mydatabase_with_structure.sql.

For large databases where memory could be an issue during the dump process, you can use the --single-transaction option with -l to create a consistent snapshot:

mysqldump -l --single-transaction mydatabase > mydatabase_snapshot.sql

This command locks tables with a read lock and performs a single transaction dump, ensuring data integrity.

When you need to dump data from a MySQL server running on a remote machine, you can specify the host and credentials along with the lock tables option:

mysqldump -h remote_host -u username -p -l mydatabase > remote_backup.sql

This command locks tables in mydatabase on the remote host remote_host using the provided username and prompts for the password.

To dump a database with a specific character set and collation while locking tables, you can specify these options along with -l:

mysqldump -l --default-character-set=utf8mb4 --result-file=mydatabase_utf8.sql mydatabase

This command locks all tables in mydatabase and sets the character set to utf8mb4, saving the dump as mydatabase_utf8.sql.

For dumping data from multiple databases while locking tables, you can list them together with -l:

mysqldump -l --databases database1 database2 > multi_db_backup.sql

This command locks tables in both database1 and database2, combining their dumps into multi_db_backup.sql.

Lastly, if you want to exclude specific tables from the dump while locking others, you can use the --ignore-table option with -l:

mysqldump -l --ignore-table=mydatabase.table3 mydatabase > exclude_table_backup.sql

This command locks all tables in mydatabase except table3, saving the dump as exclude_table_backup.sql.

Also check similar articles.

Locking All Tables Across Databases in mysqldump
Setting Line Terminator in mysqldump Output
Using INSERT IGNORE Statements in mysqldump
Including Master Host and Port in mysqldump Output (Deprecated)
Including Source Host and Port in mysqldump Output