MySQL How do you restore tablespace

MySQL How do you restore tablespace?

This is not new information but I have not covered it much so addressing it now for those that need it.

If you lose your ibd files... you lose your data. So if you have a copy of one available.. or even if you are syncing from another database you can still import it.  What/how do you lose tablespace?

Here is a simple example to recover tablespace.



mysql> Create database demo;

mysql> use demo;

mysql> CREATE TABLE `demotable` (
    ->   `id` int(11) NOT NULL AUTO_INCREMENT,
    ->   `dts` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    ->   PRIMARY KEY (`id`)
    -> ) ENGINE=InnoDB;


Now we store some data...


mysql> INSERT INTO demotable (id) VALUES (NULL);
Query OK, 1 row affected (0.10 sec)

mysql> INSERT INTO demotable (id) VALUES (NULL);
Query OK, 1 row affected (0.08 sec)

mysql> SELECT * FROM demotable;
+----+---------------------+
| id | dts                 |
+----+---------------------+
|  1 | 2019-07-12 23:31:34 |
|  2 | 2019-07-12 23:31:35 |
+----+---------------------+
2 rows in set (0.00 sec)


OK now lets break it..


# systemctl stop mysqld
# cd /var/lib/mysql/demo/
# ls -ltr
total 80
-rw-r-----. 1 mysql mysql 114688 Jul 12 23:31 demotable.ibd
# mv demotable.ibd /tmp/

# systemctl start mysqld
# mysql demo

mysql> show tables;
+----------------+
| Tables_in_demo |
+----------------+
| demotable      |
+----------------+
1 row in set (0.00 sec)

mysql> desc demotable;
+-------+-----------+------+-----+-------------------+-----------------------------------------------+
| Field | Type      | Null | Key | Default           | Extra                                         |
+-------+-----------+------+-----+-------------------+-----------------------------------------------+
| id    | int(11)   | NO   | PRI | NULL              | auto_increment                                |
| dts   | timestamp | NO   |     | CURRENT_TIMESTAMP | DEFAULT_GENERATED on update CURRENT_TIMESTAMP |
+-------+-----------+------+-----+-------------------+-----------------------------------------------+
2 rows in set (0.01 sec)

mysql> INSERT INTO demotable (id) VALUES (NULL);
ERROR 1812 (HY000): Tablespace is missing for table `demo`.`demotable`.


Broken and lost tablespace... Now we can recover it..


demo]# cp /tmp/demotable.ibd .

mysql> ALTER TABLE demotable DISCARD TABLESPACE;

demo]# cp /tmp/demotable.ibd .
demo]# ls -ltr
total 112
-rw-r-----. 1 root root 114688 Jul 12 23:50 demotable.ibd
demo]# chown mysql:mysql demotable.ibd
demo]# mysql demo
mysql> ALTER TABLE demotable IMPORT TABLESPACE;
ERROR 1034 (HY000): Incorrect key file for table 'demotable'; try to repair it

mysql> REPAIR TABLE demotable;
+----------------+--------+----------+---------------------------------------------------------+
| Table          | Op     | Msg_type | Msg_text                                                |
+----------------+--------+----------+---------------------------------------------------------+
| demo.demotable | repair | note     | The storage engine for the table doesn't support repair |
+----------------+--------+----------+---------------------------------------------------------+


Notice now we also got another error.. This is usually tied to space available to tmpdir, and repair doesn't work for .ibd anyway.


mysql> select @@tmpdir;
+----------+
| @@tmpdir |
+----------+
| /tmp     |
+----------+

# vi /etc/my.cnf
tmpdir=/var/lib/mysql-files/

# systemctl restart mysqld
# mysql demo


OK used the mysql-files directory just for example.
Now we can try again.


mysql> ALTER TABLE demotable IMPORT TABLESPACE;
Query OK, 0 rows affected, 1 warning (0.61 sec)

mysql>  INSERT INTO demotable (id) VALUES (NULL);
Query OK, 1 row affected (0.11 sec)

mysql>  SELECT * FROM demotable;
+----+---------------------+
| id | dts                 |
+----+---------------------+
|  1 | 2019-07-12 23:31:34 |
|  2 | 2019-07-12 23:31:35 |
|  3 | 2019-07-12 23:56:08 |
+----+---------------------+


OK worked.
Now, this is all nice and simple if you just have one table. But what about 100s...

Automate it, of course, and use your information_schema to help.

Make a few more copies for test.


mysql> create table demotable1 like demotable;
Query OK, 0 rows affected (0.51 sec)

mysql> create table demotable2 like demotable;
Query OK, 0 rows affected (1.04 sec)

mysql> create table demotable3 like demotable;
Query OK, 0 rows affected (0.74 sec)

mysql> create table demotable4 like demotable;
Query OK, 0 rows affected (2.21 sec)


break them all..


demo]# mv *.ibd /tmp/


Now using your information_schema.tables table, you can build out all the commands you will need.


# vi build_discard.sql
# cat build_discard.sql
SELECT CONCAT(" ALTER TABLE ",TABLE_SCHEMA,".",TABLE_NAME," DISCARD TABLESPACE;  ") as CMD FROM information_schema.TABLES WHERE TABLE_SCHEMA='demo';

# vi build_import.sql
# cat build_import.sql
SELECT CONCAT(" ALTER TABLE ",TABLE_SCHEMA,".",TABLE_NAME," IMPORT TABLESPACE;  ") as CMD FROM information_schema.TABLES WHERE TABLE_SCHEMA='demo';



# mysql -N < build_import.sql > import_tablespace.sql
# mysql -N < build_discard.sql  | mysql demo

demo]# cp /tmp/*.ibd .
demo]# chown mysql:mysql *.ibd
# systemctl restart mysqld
# mysql demo < import_tablespace.sql
# mysql demo

mysql> INSERT INTO demotable (id) VALUES (NULL);
Query OK, 1 row affected (0.08 sec)

mysql> INSERT INTO demotable1 (id) VALUES (NULL);
Query OK, 1 row affected (0.05 sec)

mysql> INSERT INTO demotable2 (id) VALUES (NULL);
Query OK, 1 row affected (0.09 sec)

mysql> INSERT INTO demotable3 (id) VALUES (NULL);
^[[AQuery OK, 1 row affected (0.37 sec)

mysql> INSERT INTO demotable4 (id) VALUES (NULL);
Query OK, 1 row affected (0.12 sec)


And it worked.