ndb_desc provides a detailed description of
one or more NDB
tables.
Usage:
ndb_desc -cconnect_string
tbl_name
-ddb_name
[-p]
Sample Output:
MySQL table creation and population statements:
USE test; CREATE TABLE fish ( id INT(11) NOT NULL AUTO_INCREMENT, name VARCHAR(20) NOT NULL, length_mm INT(11) NOT NULL, weight_gm INT(11) NOT NULL, PRIMARY KEY pk (id), UNIQUE KEY uk (name) ) ENGINE=NDB; INSERT INTO fish VALUES ('','guppy', 35, 2), ('','tuna', 2500, 150000), ('','shark', 3000, 110000), ('','manta ray', 1500, 50000), ('','grouper', 900, 125000), ('','puffer', 250, 2500);
Output from ndb_desc:
shell> ./ndb_desc -c localhost fish -d test -p
-- fish --
Version: 2
Fragment type: 9
K Value: 6
Min load factor: 78
Max load factor: 80
Temporary table: no
Number of attributes: 4
Number of primary keys: 1
Length of frm data: 311
Row Checksum: 1
Row GCI: 1
SingleUserMode: 0
ForceVarPart: 1
FragmentCount: 2
TableStatus: Retrieved
-- Attributes --
id Int PRIMARY KEY DISTRIBUTION KEY AT=FIXED ST=MEMORY AUTO_INCR
name Varchar(20;latin1_swedish_ci) NOT NULL AT=SHORT_VAR ST=MEMORY
length_mm Int NOT NULL AT=FIXED ST=MEMORY
weight_gm Int NOT NULL AT=FIXED ST=MEMORY
-- Indexes --
PRIMARY KEY(id) - UniqueHashIndex
PRIMARY(id) - OrderedIndex
uk$unique(name) - UniqueHashIndex
uk(name) - OrderedIndex
-- Per partition info --
Partition Row count Commit count Frag fixed memory Frag varsized memory Extent_space Free extent_space
0 2 2 32768 32768 0 0
1 4 4 32768 32768 0 0
NDBT_ProgramExit: 0 - OK
Information about multiple tables can be obtained in a single invocation of ndb_desc by using their names, separated by spaces. All of the tables must be in the same database.
The Extent_space
and Free
extent_space
columns were added in MySQL Cluster NDB
6.3.27 and MySQL Cluster NDB 7.0.8. They are applicable only
to NDB
tables having columns on disk; for
tables having only in-memory columns, these columns always
contain the value 0
.
To illustrate their use, we modify the previous example. First, we must create the necessary Disk Data objects, as shown here:
CREATE LOGFILE GROUP lg_1 ADD UNDOFILE 'undo_1.log' INITIAL_SIZE 16M UNDO_BUFFER_SIZE 2M ENGINE NDB; ALTER LOGFILE GROUP lg_1 ADD UNDOFILE 'undo_2.log' INITIAL_SIZE 12M ENGINE NDB; CREATE TABLESPACE ts_1 ADD DATAFILE 'data_1.dat' USE LOGFILE GROUP lg_1 INITIAL_SIZE 32M ENGINE NDB; ALTER TABLESPACE ts_1 ADD DATAFILE 'data_2.dat' INITIAL_SIZE 48M ENGINE NDB;
(For more information on the statements just shown and the
objects created by them, see
Section 17.5.10.1, “MySQL Cluster Disk Data Objects”, as well as
Section 12.1.14, “CREATE LOGFILE GROUP
Syntax”, and
Section 12.1.18, “CREATE TABLESPACE
Syntax”.)
Now we can create and populate a version of the
fish
table that stores 2 of its columns on
disk (deleting the previous version of the table first, if it
already exists):
CREATE TABLE fish ( id INT(11) NOT NULL AUTO_INCREMENT, name VARCHAR(20) NOT NULL, length_mm INT(11) NOT NULL, weight_gm INT(11) NOT NULL, PRIMARY KEY pk (id), UNIQUE KEY uk (name) ) TABLESPACE ts_1 STORAGE DISK ENGINE=NDB; INSERT INTO fish VALUES ('','guppy', 35, 2), ('','tuna', 2500, 150000), ('','shark', 3000, 110000), ('','manta ray', 1500, 50000), ('','grouper', 900, 125000), ('','puffer', 250, 2500);
When run against this version of the table, ndb_desc displays the following output:
shell> ./ndb_desc -c localhost fish -d test -p
-- fish --
Version: 3
Fragment type: 9
K Value: 6
Min load factor: 78
Max load factor: 80
Temporary table: no
Number of attributes: 4
Number of primary keys: 1
Length of frm data: 321
Row Checksum: 1
Row GCI: 1
SingleUserMode: 0
ForceVarPart: 1
FragmentCount: 2
TableStatus: Retrieved
-- Attributes --
id Int PRIMARY KEY DISTRIBUTION KEY AT=FIXED ST=MEMORY AUTO_INCR
name Varchar(20;latin1_swedish_ci) NOT NULL AT=SHORT_VAR ST=MEMORY
length_mm Int NOT NULL AT=FIXED ST=DISK
weight_gm Int NOT NULL AT=FIXED ST=DISK
-- Indexes --
PRIMARY KEY(id) - UniqueHashIndex
PRIMARY(id) - OrderedIndex
uk$unique(name) - UniqueHashIndex
uk(name) - OrderedIndex
-- Per partition info --
Partition Row count Commit count Frag fixed memory Frag varsized memory Extent_space Free extent_space
0 2 2 32768 32768 1048576 1044440
1 4 4 32768 32768 1048576 1044400
NDBT_ProgramExit: 0 - OK
This means that 1048576 bytes are allocated from the
tablespace for this table on each partition, of which 1044440
bytes remain free for additional storage. In other words,
1048576 - 1044440 = 4136 bytes per partition is currently
being used to store the data from this table's disk-based
columns. The number of bytes shown as Free
extent_space
is available for storing on-disk column
data from the fish
table only; for this
reason, it is not visible when selecting from the
INFORMATION_SCHEMA.FILES
table.
Additional Options:
Print additional information about the table's partitions.
Include information about subordinate
BLOB
and
TEXT
columns.
Use of this option also requires the use of the
--extra-partition-info
(-p
) option.
This option was added in MySQL Cluster NDB 6.3.32, MySQL Cluster NDB 7.0.13, and MySQL Cluster NDB 7.1.2.
Include information about the mappings between table partitions and the data nodes upon which they reside. This information can be useful for verifying distribution awareness mechanisms and supporting more efficient application access to the data stored in MySQL Cluster.
Use of this option also requires the use of the
--extra-partition-info
(-p
) option.
This option was added in MySQL Cluster NDB 6.2.19, MySQL Cluster NDB 6.3.33, MySQL Cluster NDB 7.0.14, and MySQL Cluster NDB 7.1.2.
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