A general tablespace is a shared
tablespace that is created using
TABLESPACE syntax. General tablespace capabilities and
features are described under the following topics in this section:
The general tablespace feature provides the following capabilities:
Similar to the system tablespace, general tablespaces are shared tablespaces that can store data for multiple tables.
General tablespaces have a potential memory advantage over file-per-table tablespaces. The server keeps tablespace metadata in memory for the lifetime of a tablespace. Multiple tables in fewer general tablespaces consume less memory for tablespace metadata than the same number of tables in separate file-per-table tablespaces.
General tablespace data files may be placed in a directory relative to or independent of the MySQL data directory, which provides you with many of the data file and storage management capabilities of file-per-table tablespaces. As with file-per-table tablespaces, the ability to place data files outside of the MySQL data directory allows you to manage performance of critical tables separately, setup RAID or DRBD for specific tables, or bind tables to particular disks, for example.
General tablespaces support all table row formats and associated features.
TABLESPACEoption can be used with
CREATE TABLEto create tables in a general tablespaces, file-per-table tablespace, or in the system tablespace.
TABLESPACEoption can be used with
ALTER TABLEto move tables between general tablespaces, file-per-table tablespaces, and the system tablespace. Previously, it was not possible to move a table from a file-per-table tablespace to the system tablespace. With the general tablespace feature, you can now do so.
General tablespaces are created using
CREATE TABLESPACE syntax.
CREATE TABLESPACE tablespace_name [ADD DATAFILE 'file_name'] [FILE_BLOCK_SIZE = value] [ENGINE [=] engine_name]
A general tablespace can be created in the data directory or
outside of it. To avoid conflicts with implicitly created
file-per-table tablespaces, creating a general tablespace in a
subdirectory under the data directory is not supported. When
creating a general tablespace outside of the data directory, the
directory must exist and must be known to
InnoDB prior to creating the tablespace. To
make an unknown directory known to
add the directory to the
innodb_directories is a
read-only startup option. Configuring it requires restarting the
Creating a general tablespace in the data directory:
mysql> CREATE TABLESPACE `ts1` ADD DATAFILE 'ts1.ibd' Engine=InnoDB;
mysql> CREATE TABLESPACE `ts1` Engine=InnoDB;
ADD DATAFILE clause is optional as of
MySQL 8.0.14 and required before that. If the
DATAFILE clause is not specified when creating a
tablespace, a tablespace data file with a unique file name is
created implicitly. The unique file name is a 128 bit UUID
formatted into five groups of hexadecimal numbers separated by
General tablespace data files include an
.ibd file extension. In a replication
environment, the data file name created on the source is not the
same as the data file name created on the replica.
Creating a general tablespace in a directory outside of the data directory:
mysql> CREATE TABLESPACE `ts1` ADD DATAFILE '/my/tablespace/directory/ts1.ibd' Engine=InnoDB;
You can specify a path that is relative to the data directory as
long as the tablespace directory is not under the data
directory. In this example, the
my_tablespace directory is at the same
level as the data directory:
mysql> CREATE TABLESPACE `ts1` ADD DATAFILE '../my_tablespace/ts1.ibd' Engine=InnoDB;
After creating an
InnoDB general tablespace,
you can use
tbl_name ... TABLESPACE [=]
tables to the tablespace, as shown in the following examples:
tbl_name TABLESPACE [=]
mysql> CREATE TABLE t1 (c1 INT PRIMARY KEY) TABLESPACE ts1;
mysql> ALTER TABLE t2 TABLESPACE ts1;
Support for adding table partitions to shared tablespaces was
deprecated in MySQL 5.7.24 and removed in MySQL 8.0.13. Shared
tablespaces include the
tablespace and general tablespaces.
General tablespaces support all table row formats
the caveat that compressed and uncompressed tables cannot
coexist in the same general tablespace due to different physical
For a general tablespace to contain compressed tables
FILE_BLOCK_SIZE must be specified, and the
FILE_BLOCK_SIZE value must be a valid
compressed page size in relation to the
innodb_page_size value. Also,
the physical page size of the compressed table
KEY_BLOCK_SIZE) must be equal to
FILE_BLOCK_SIZE/1024. For example, if
KEY_BLOCK_SIZE of the table must be 8.
The following table shows permitted
FILE_BLOCK_SIZE values may also be specified
in bytes. To determine a valid
value for a given
FILE_BLOCK_SIZE, divide the
FILE_BLOCK_SIZE value by 1024. Table
compression is not support for 32K and 64K
InnoDB page sizes. For more information about
CREATE TABLE, and
Section 188.8.131.52, “Creating Compressed Tables”.
Table 15.3 Permitted Page Size, FILE_BLOCK_SIZE, and KEY_BLOCK_SIZE Combinations for Compressed Tables
|InnoDB Page Size (innodb_page_size)||Permitted FILE_BLOCK_SIZE Value||Permitted KEY_BLOCK_SIZE Value|
|64KB||64K (65536)||Compression is not supported|
|32KB||32K (32768)||Compression is not supported|
|16KB||16K (16384)||N/A: If
|8KB||8K (8192)||N/A: If
|4KB||4K (4096)||N/A: If
This example demonstrates creating a general tablespace and
adding a compressed table. The example assumes a default
innodb_page_size of 16KB. The
FILE_BLOCK_SIZE of 8192 requires that the
compressed table have a
KEY_BLOCK_SIZE of 8.
mysql> CREATE TABLESPACE `ts2` ADD DATAFILE 'ts2.ibd' FILE_BLOCK_SIZE = 8192 Engine=InnoDB; mysql> CREATE TABLE t4 (c1 INT PRIMARY KEY) TABLESPACE ts2 ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=8;
If you do not specify
creating a general tablespace,
FILE_BLOCK_SIZE defaults to
FILE_BLOCK_SIZE is equal to
tablespace may only contain tables with an uncompressed row
You can use
ALTER TABLE with the
TABLESPACE option to move a table to an
existing general tablespace, to a new file-per-table tablespace,
or to the system tablespace.
Support for placing table partitions in shared tablespaces was
deprecated in MySQL 5.7.24 and removed MySQL 8.0.13. Shared
tablespaces include the
tablespace and general tablespaces.
To move a table from a file-per-table tablespace or from the
system tablespace to a general tablespace, specify the name of
the general tablespace. The general tablespace must exist. See
CREATE TABLESPACE for more
ALTER TABLE tbl_name TABLESPACE [=] tablespace_name;
To move a table from a general tablespace or file-per-table
tablespace to the system tablespace, specify
innodb_system as the tablespace name.
ALTER TABLE tbl_name TABLESPACE [=] innodb_system;
To move a table from the system tablespace or a general
tablespace to a file-per-table tablespace, specify
innodb_file_per_table as the tablespace name.
ALTER TABLE tbl_name TABLESPACE [=] innodb_file_per_table;
ALTER TABLE ... TABLESPACE operations always
cause a full table rebuild, even if the
TABLESPACE attribute has not changed from its
ALTER TABLE ... TABLESPACE syntax does not
support moving a table from a temporary tablespace to a
DATA DIRECTORY clause is permitted with
CREATE TABLE ...
TABLESPACE=innodb_file_per_table but is otherwise not
supported for use in combination with the
TABLESPACE option. As of MySQL 8.0.21, the
directory specified in a
clause must be known to
InnoDB. For more
Using the DATA DIRECTORY Clause.
Restrictions apply when moving tables from encrypted tablespaces. See Encryption Limitations.
Renaming a general tablespace is supported using
TABLESPACE ... RENAME TO syntax.
ALTER TABLESPACE s1 RENAME TO s2;
CREATE TABLESPACE privilege
is required to rename a general tablespace.
Exclusive metadata locks are taken on tables within a general tablespace while the tablespace is renamed, which prevents concurrent DDL. Concurrent DML is supported.
DROP TABLESPACE statement is
used to drop an
InnoDB general tablespace.
Use a query similar to the following to identify tables in a general tablespace.
mysql> SELECT a.NAME AS space_name, b.NAME AS table_name FROM INFORMATION_SCHEMA.INNODB_TABLESPACES a, INFORMATION_SCHEMA.INNODB_TABLES b WHERE a.SPACE=b.SPACE AND a.NAME LIKE 'ts1'; +------------+------------+ | space_name | table_name | +------------+------------+ | ts1 | test/t1 | | ts1 | test/t2 | | ts1 | test/t3 | +------------+------------+
InnoDB tablespace is not deleted
automatically when the last table in the tablespace is dropped.
The tablespace must be dropped explicitly using
A general tablespace does not belong to any particular database.
DROP DATABASE operation can
drop tables that belong to a general tablespace but it cannot
drop the tablespace, even if the
DATABASE operation drops all tables that belong to the
tablespace. A general tablespace must be dropped explicitly
Similar to the system tablespace, truncating or dropping tables
stored in a general tablespace creates free space internally in
the general tablespace .ibd data
file which can only be used for new
InnoDB data. Space is not released back to
the operating system as it is when a file-per-table tablespace
is deleted during a
This example demonstrates how to drop an
InnoDB general tablespace. The general
ts1 is created with a single
table. The table must be dropped before dropping the tablespace.
mysql> CREATE TABLESPACE `ts1` ADD DATAFILE 'ts1.ibd' Engine=InnoDB; mysql> CREATE TABLE t1 (c1 INT PRIMARY KEY) TABLESPACE ts1 Engine=InnoDB; mysql> DROP TABLE t1; mysql> DROP TABLESPACE ts1;
is a case-sensitive identifier in MySQL.
A generated or existing tablespace cannot be changed to a general tablespace.
Creation of temporary general tablespaces is not supported.
General tablespaces do not support temporary tables.
Similar to the system tablespace, truncating or dropping tables stored in a general tablespace creates free space internally in the general tablespace .ibd data file which can only be used for new
InnoDBdata. Space is not released back to the operating system as it is for file-per-table tablespaces.
Additionally, a table-copying
ALTER TABLEoperation on table that resides in a shared tablespace (a general tablespace or the system tablespace) can increase the amount of space used by the tablespace. Such operations require as much additional space as the data in the table plus indexes. The additional space required for the table-copying
ALTER TABLEoperation is not released back to the operating system as it is for file-per-table tablespaces.
Support for placing table partitions in general tablespaces was deprecated in MySQL 5.7.24 and removed in MySQL 8.0.13.
ADD DATAFILEclause is not supported in a replication environment where the source and replica reside on the same host, as it would cause the source and replica to create a tablespace of the same name in the same location, which is not supported. However, if the
ADD DATAFILEclause is omitted, the tablespace is created in the data directory with a generated file name that is unique, which is permitted.
As of MySQL 8.0.21, general tablespaces cannot be created in the undo tablespace directory (
innodb_undo_directory) unless that directly is known to
InnoDB. Known directories are those defined by the