tablespace_nameADD DATAFILE '
file_name' USE LOGFILE GROUP
extent_size] [INITIAL_SIZE [=]
initial_size] [AUTOEXTEND_SIZE [=]
autoextend_size] [MAX_SIZE [=]
max_size] [NODEGROUP [=]
nodegroup_id] [WAIT] [COMMENT [=]
comment_text] ENGINE [=]
This statement is used to create a tablespace, which can contain
one or more data files, providing storage space for tables. One
data file is created and added to the tablespace using this
statement. Additional data files may be added to the tablespace by
statement (see Section 13.1.8, “ALTER TABLESPACE Syntax”). For rules
covering the naming of tablespaces, see
Section 9.2, “Schema Object Names”.
All NDB Cluster Disk Data objects share the same namespace. This means that each Disk Data object must be uniquely named (and not merely each Disk Data object of a given type). For example, you cannot have a tablespace and a log file group with the same name, or a tablespace and a data file with the same name.
A log file group of one or more
UNDO log files
must be assigned to the tablespace to be created with the
USE LOGFILE GROUP clause.
logfile_group must be an existing log
file group created with
GROUP (see Section 13.1.14, “CREATE LOGFILE GROUP Syntax”).
Multiple tablespaces may use the same log file group for
EXTENT_SIZE sets the size, in bytes, of the
extents used by any files belonging to the tablespace. The default
value is 1M. The minimum size is 32K, and theoretical maximum is
2G, although the practical maximum size depends on a number of
factors. In most cases, changing the extent size does not have any
measurable effect on performance, and the default value is
recommended for all but the most unusual situations.
An extent is a unit of disk
space allocation. One extent is filled with as much data as that
extent can contain before another extent is used. In theory, up to
65,535 (64K) extents may used per data file; however, the
recommended maximum is 32,768 (32K). The recommended maximum size
for a single data file is 32G—that is, 32K extents × 1
MB per extent. In addition, once an extent is allocated to a given
partition, it cannot be used to store data from a different
partition; an extent cannot store data from more than one
partition. This means, for example that a tablespace having a
single datafile whose
INITIAL_SIZE is 256 MB
EXTENT_SIZE is 128M has just two
extents, and so can be used to store data from at most two
different disk data table partitions.
You can see how many extents remain free in a given data file by
table, and so derive an estimate for how much space remains free
in the file. For further discussion and examples, see
Section 21.30.1, “The INFORMATION_SCHEMA FILES Table”.
INITIAL_SIZE parameter sets the data file's
total size in bytes. Once the file has been created, its size
cannot be changed; however, you can add more data files to the
ALTER TABLESPACE ... ADD
DATAFILE. See Section 13.1.8, “ALTER TABLESPACE Syntax”.
INITIAL_SIZE is optional; its default value is
134217728 (128 MB).
On 32-bit systems, the maximum supported value for
INITIAL_SIZE is 4294967296 (4 GB). (Bug #29186)
EXTENT_SIZE, you may optionally
follow the number with a one-letter abbreviation for an order of
magnitude, similar to those used in
Generally, this is one of the letters
G (for gigabytes). In MySQL NDB
Cluster 7.3.2 and later, these abbreviations are also supported
INITIAL_SIZE as well. (Bug
#13116514, Bug #16104705, Bug #62858)
UNDO_BUFFER_SIZE are subject to rounding as
UNDO_BUFFER_SIZEare each rounded up to the nearest whole multiple of 32K.
INITIAL_SIZEis rounded down to the nearest whole multiple of 32K.
For data files, INITIAL_SIZE is subject to further rounding; the result just obtained is rounded up to the nearest whole multiple of
EXTENT_SIZE(after any rounding).
The rounding just described is done explicitly, and a warning is
issued by the MySQL Server when any such rounding is performed.
The rounded values are also used by the NDB kernel for calculating
values and other purposes. However, to avoid an unexpected result,
we suggest that you always use whole multiples of 32K in
specifying these options.
COMMENT are parsed but ignored, and so
currently have no effect. These options are intended for future
ENGINE parameter determines the storage
engine which uses this tablespace, with
engine_name being the name of the
storage engine. Currently,
must be one of the values
CREATE TABLESPACE is used with
ENGINE = NDB, a tablespace and associated data
file are created on each Cluster data node. You can verify that
the data files were created and obtain information about them by
table. For example:
SELECT LOGFILE_GROUP_NAME, FILE_NAME, EXTRA->
WHERE TABLESPACE_NAME = 'newts' AND FILE_TYPE = 'DATAFILE';+--------------------+-------------+----------------+ | LOGFILE_GROUP_NAME | FILE_NAME | EXTRA | +--------------------+-------------+----------------+ | lg_3 | newdata.dat | CLUSTER_NODE=3 | | lg_3 | newdata.dat | CLUSTER_NODE=4 | +--------------------+-------------+----------------+ 2 rows in set (0.01 sec)