The 'applicationdb' is using InnoDB and consuming a large amount of file system space. You have a / backup partition available on NFS where backups are stored. You investigate and gather this information:

[mysqld]
datadir=/var/lib/mysql/
innodb_file_per_table=0

Three tables are stored in the InnoDB shared tablespace and the details are as follows:

* The table data_current has 1,000,000 rows.
* The table data_reports has 1,500,000 rows.
* The table data_archive has 4,500,000 rows.

shell ls -l /var/lib/mysql/
-rw-rw---- 1 mysql mysql 744G Aug 26 14:34 ibdatal
-rw-rw---- 1 mysql mysql 480M Aug 26 13:34 ib_logfile0
-rw-rw---- 1 mysql mysql 480M Aug 26 13:47 ib_logfile1
...

You attempt to free space from ibdatal by taking a mysqldump of the data_archive table and storing it on your backup partition.

shell mysqldump -u root -p applicationdb data_archive /backup/data_archive.sql
mysql DROP TABLE data_archive;

Unfortunately, this action does not free any actual disk space back to the file system and the server disk space is running out. Which set of actions will allow you to free disk space back to the file system?

Question

The 'applicationdb' is using InnoDB and consuming a large amount of file system space. You have a / backup partition available on NFS where backups are stored. You investigate and gather this information:

[mysqld]
datadir=/var/lib/mysql/
innodb_file_per_table=0

Three tables are stored in the InnoDB shared tablespace and the details are as follows:

* The table data_current has 1,000,000 rows.
* The table data_reports has 1,500,000 rows.
* The table data_archive has 4,500,000 rows.

shell> ls -l /var/lib/mysql/
-rw-rw---- 1 mysql mysql 744G Aug 26 14:34 ibdatal
-rw-rw---- 1 mysql mysql 480M Aug 26 13:34 ib_logfile0
-rw-rw---- 1 mysql mysql 480M Aug 26 13:47 ib_logfile1
...

You attempt to free space from ibdatal by taking a mysqldump of the data_archive table and storing it on your backup partition.

shell> mysqldump -u root -p applicationdb data_archive > /backup/data_archive.sql
mysql> DROP TABLE data_archive;

Unfortunately, this action does not free any actual disk space back to the file system and the server disk space is running out. Which set of actions will allow you to free disk space back to the file system?

Accepted Answer

A. Enable compression on the table, causing InnoDB to release unused pages on disk to the file system: mysql> SET GLOBAL innodb_file_per_table=1; mysql> SET GLOBAL innodb_file_format=Barracuda; mysql> ALTER TABLE data_current ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=8; mysql> ALTER TABLE data_history ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=8;

Answer

B. Execute OPTIMIZE TABLE so that the InnoDB engine frees unused pages on disk back to the file system: mysql> OPTIMIZE TABLE data_current, data_reports;

Answer

C. Set the server to use its own tablespace, and then alter the table so that data is moved from the shared tablespace to its own: mysql> SET GLOBAL innodb_file_per_table=1; mysql> ALTER TABLE data_current ENGINE=InnoDB; mysql> ALTER TABLE data_reports ENGINE=InnoDB;

Answer

D. Take a backup, stop the server, remove the data files, and restore the backup: shell> mysqldump -u root -p applicationdb > /backup/applicationdb.sql shell> /etc/init.d/mysql stop shell> cd /var/lib/mysql/ shell> rm ibdatal ib_logfil0 ib_logfile1 shell> /etc/init.d/mysql start shell> mysql -u root -p applicationdb < /backup/applicationdb.sql

The 'applicationdb' is using InnoDB and consuming a large amount of file system space. You have a / backup partition available on NFS where backups are stored. You investigate and gather this…

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