Examine this command, which executes successfully: shell> mysqldump --master-data=2 --single-transaction --result-file=dump.sql mydb Which two statements are true? (Choose two.)
A.
It executes flush tables with read lock.
B.
It enforces consistent backups for all storage engines.
C.
The backup created is a consistent data dump.
D.
This option uses the READ COMMITTED transaction isolation mode.
They are all wrong.
It would be B and C if only innodb storage engine is used. MyISAM tables are not consistently backed up
https://dev.mysql.com/doc/refman/8.0/en/mysqldump.html#option_mysqldump_single-transaction
"When using this option, you should keep in mind that only InnoDB tables are dumped in a consistent state. For example, any MyISAM or MEMORY tables dumped while using this option may still change state."
B. It enforces consistent backups for all storage engines.
This statement is true. The --single-transaction option enforces a consistent backup for all storage engines by using a single transaction to capture the data, making sure that the data dump is consistent across different storage engines.
C. The backup created is a consistent data dump.
This statement is true. The --single-transaction option ensures a consistent data dump by capturing data from a single transaction, preventing inconsistencies due to concurrent write operations.
--single-transaction
This option sets the transaction isolation mode to REPEATABLE READ and sends a START TRANSACTION SQL statement to the server before dumping data. It is useful only with transactional tables such as InnoDB, because then it dumps the consistent state of the database at the time when START TRANSACTION was issued without blocking any applications.
--single-transaction
This option sets the transaction isolation mode to REPEATABLE READ and sends a START TRANSACTION SQL statement to the server before dumping data. It is useful only with transactional tables such as InnoDB, because then it dumps the consistent state of the database at the time when START TRANSACTION was issued without blocking any applications.
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