table is in the system tablespace 0 which cannot be discarded - mysql

Question

I am trying to run this query:
alter table about_member discard tablespace;
But when I do, my error logs are outputting this:
InnoDB: Error: table `diskise`.`about_member`
InnoDB: is in the system tablespace 0 which cannot be discarded
What can I do so I can discard this tablespace so I can import a backup that I have?

Answer 1

See this manual page:
By default, all InnoDB tables and indexes are stored in the system tablespace. As an alternative, you can store each InnoDB table and its indexes in its own file. This feature is called “multiple tablespaces” because each table that is created when this setting is in effect has its own tablespace.
Advantages of Per-Table Tablespaces
You can reclaim disk space when truncating or dropping a table. For tables created when file-per-table mode is turned off, truncating or dropping them creates free space internally in the ibdata files. That free space can only be used for new InnoDB data.
It sounds like you created your table in the default tablespace, so you cannot discard the tablespace. That said, you should be able to import data without discarding a tablespace first, unless you're just out of disk space.

Answer 2

I just ran into same problem while I was trying to restore one table from .ibd file. I know it's been a long time so I wrote this here for people who still running into the same problem.
Continuing with #Ed Cottrell's answer, you will need to change the mysql global variable innodb_file_per_table to let mysql to store .ibd in your own file instead of using system tablespace.
To achieve this you can do (also see official docs):
change your my.cnf file, adding following line and restart mysql server
[mysqld]
innodb_file_per_table=1
set global variable in mysql command (sometimes not working due to security issue)
SET GLOBAL innodb_file_per_table=1;
You may need to DROP your table before this take effects.
After doing this, you will be able to see .ibd files inside PATH/TO/MYSQL/DB_NAME directory (e.g. /var/lib/mysql/DB_NAME).