MySQL 5.6 Reference Manual Including MySQL NDB Cluster 7.3-7.4 Reference Guide
ndb_desc provides a detailed description of
one or more NDB
tables.
ndb_desc -cconnection_string
tbl_name
-ddb_name
[options
] ndb_desc -cconnection_string
index_name
-ddb_name
-ttbl_name
Additional options that can be used with ndb_desc are listed later in this section.
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$unique(name) - UniqueHashIndex
uk(name) - OrderedIndex
-- Per partition info --
Partition Row count Commit count Frag fixed memory ...
0 2 2 32768 ...
1 4 4 32768 ...
... Frag varsized memory Extent_space Free extent_space
... 32768 0 0
... 32768 0 0
NDBT_ProgramExit: 0 - OK
Information about multiple tables can be obtained in a single invocation of ndb_desc by using their names, separated by spaces. All of the tables must be in the same database.
You can obtain additional information about a specific index
using the --table
(short form:
-t
) option and supplying the name of the index
as the first argument to ndb_desc, as shown
here:
shell> ./ndb_desc uk -d test -t fish
-- uk --
Version: 3
Base table: fish
Number of attributes: 1
Logging: 0
Index type: OrderedIndex
Index status: Retrieved
-- Attributes --
name Varchar(20;latin1_swedish_ci) NOT NULL AT=SHORT_VAR ST=MEMORY
-- IndexTable 10/uk --
Version: 3
Fragment type: FragUndefined
K Value: 6
Min load factor: 78
Max load factor: 80
Temporary table: yes
Number of attributes: 2
Number of primary keys: 1
Length of frm data: 0
Row Checksum: 1
Row GCI: 1
SingleUserMode: 2
ForceVarPart: 0
FragmentCount: 4
ExtraRowGciBits: 0
ExtraRowAuthorBits: 0
TableStatus: Retrieved
-- Attributes --
name Varchar(20;latin1_swedish_ci) NOT NULL AT=SHORT_VAR ST=MEMORY
NDB$TNODE Unsigned [64] PRIMARY KEY DISTRIBUTION KEY AT=FIXED ST=MEMORY
-- Indexes --
PRIMARY KEY(NDB$TNODE) - UniqueHashIndex
NDBT_ProgramExit: 0 - OK
When an index is specified in this way, the
--extra-partition-info
and
--extra-node-info
options have
no effect.
The Version
column in the output contains the
table's schema object version. For information about
interpreting this value, see
NDB Schema Object Versions.
The Extent_space
and Free
extent_space
columns 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 18.5.10.1, “NDB Cluster Disk Data Objects”, as well as Section 13.1.14, “CREATE LOGFILE GROUP Statement”, and Section 13.1.18, “CREATE TABLESPACE Statement”.)
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 ...
0 2 2 32768 ...
1 4 4 32768 ...
... Frag varsized memory Extent_space Free extent_space
... 32768 0 0
... 32768 0 0
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.
The following table includes options that are specific to ndb_desc. Additional descriptions follow the table. For options common to most NDB Cluster programs (including ndb_desc), see Section 18.4.29, “Options Common to NDB Cluster Programs — Options Common to NDB Cluster Programs”.
Table 18.25 Command-line options for the ndb_desc program
Format | Description | Added, Deprecated, or Removed |
---|---|---|
Include partition information for BLOB tables in output. Requires that the -p option also be used | (Supported in all MySQL 5.6 based releases) |
|
Name of database containing table | (Supported in all MySQL 5.6 based releases) |
|
Include partition-to-data-node mappings in output. Requires that the -p option also be used | (Supported in all MySQL 5.6 based releases) |
|
Display information about partitions | (Supported in all MySQL 5.6 based releases) |
|
Number of times to retry the connection (once per second) | (Supported in all MySQL 5.6 based releases) |
|
Specify the table in which to find an index. When this option is used, -p and -n have no effect and are ignored | (Supported in all MySQL 5.6 based releases) |
|
Use unqualified table names | (Supported in all MySQL 5.6 based releases) |
Include information about subordinate
BLOB
and
TEXT
columns.
Use of this option also requires the use of the
--extra-partition-info
(-p
) option.
Specify the database in which the table should be found.
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 NDB Cluster.
Use of this option also requires the use of the
--extra-partition-info
(-p
) option.
Print additional information about the table's partitions.
Try to connect this many times before giving up. One connect attempt is made per second.
Specify the table in which to look for an index.
Use unqualified table names.