ndb_desc provides a detailed description of
one or more NDB
tables.
Usage
ndb_desc -c connection_string tbl_name -d db_name [options]
ndb_desc -c connection_string index_name -d db_name -t tbl_name
Additional options that can be used with ndb_desc are listed later in this section.
Sample Output
MySQL table creation and population statements:
USE test;
CREATE TABLE fish (
id INT NOT NULL AUTO_INCREMENT,
name VARCHAR(20) NOT NULL,
length_mm INT NOT NULL,
weight_gm INT NOT NULL,
PRIMARY KEY pk (id),
UNIQUE KEY uk (name)
) ENGINE=NDB;
INSERT INTO fish VALUES
(NULL, 'guppy', 35, 2), (NULL, 'tuna', 2500, 150000),
(NULL, 'shark', 3000, 110000), (NULL, 'manta ray', 1500, 50000),
(NULL, 'grouper', 900, 125000), (NULL ,'puffer', 250, 2500);
Output from ndb_desc:
$> ./ndb_desc -c localhost fish -d test -p
-- fish --
Version: 2
Fragment type: HashMapPartition
K Value: 6
Min load factor: 78
Max load factor: 80
Temporary table: no
Number of attributes: 4
Number of primary keys: 1
Length of frm data: 337
Max Rows: 0
Row Checksum: 1
Row GCI: 1
SingleUserMode: 0
ForceVarPart: 1
PartitionCount: 2
FragmentCount: 2
PartitionBalance: FOR_RP_BY_LDM
ExtraRowGciBits: 0
ExtraRowAuthorBits: 0
TableStatus: Retrieved
Table options:
HashMap: DEFAULT-HASHMAP-3840-2
-- Attributes --
id Int PRIMARY KEY DISTRIBUTION KEY AT=FIXED ST=MEMORY AUTO_INCR
name Varchar(20;latin1_swedish_ci) NOT NULL AT=SHORT_VAR ST=MEMORY DYNAMIC
length_mm Int NOT NULL AT=FIXED ST=MEMORY DYNAMIC
weight_gm Int NOT NULL AT=FIXED ST=MEMORY DYNAMIC
-- Indexes --
PRIMARY KEY(id) - UniqueHashIndex
PRIMARY(id) - OrderedIndex
uk(name) - OrderedIndex
uk$unique(name) - UniqueHashIndex
-- 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
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:
$> ./ndb_desc uk -d test -t fish
-- uk --
Version: 2
Base table: fish
Number of attributes: 1
Logging: 0
Index type: OrderedIndex
Index status: Retrieved
-- Attributes --
name Varchar(20;latin1_swedish_ci) NOT NULL AT=SHORT_VAR ST=MEMORY
-- IndexTable 10/uk --
Version: 2
Fragment type: FragUndefined
K Value: 6
Min load factor: 78
Max load factor: 80
Temporary table: yes
Number of attributes: 2
Number of primary keys: 1
Length of frm data: 0
Max Rows: 0
Row Checksum: 1
Row GCI: 1
SingleUserMode: 2
ForceVarPart: 0
PartitionCount: 2
FragmentCount: 2
FragmentCountType: ONE_PER_LDM_PER_NODE
ExtraRowGciBits: 0
ExtraRowAuthorBits: 0
TableStatus: Retrieved
Table options:
-- Attributes --
name Varchar(20;latin1_swedish_ci) NOT NULL AT=SHORT_VAR ST=MEMORY
NDB$TNODE Unsigned [64] PRIMARY KEY DISTRIBUTION KEY AT=FIXED ST=MEMORY
-- Indexes --
PRIMARY KEY(NDB$TNODE) - UniqueHashIndex
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.
Three of the table properties that can be set using
NDB_TABLE
comments embedded in
CREATE TABLE
and
ALTER TABLE
statements are also
visible in ndb_desc output. The table's
FRAGMENT_COUNT_TYPE
is always shown in the
FragmentCountType
column.
READ_ONLY
and
FULLY_REPLICATED
, if set to 1, are shown in
the Table options
column. You can see this
after executing the following ALTER
TABLE
statement in the mysql
client:
mysql> ALTER TABLE fish COMMENT='NDB_TABLE=READ_ONLY=1,FULLY_REPLICATED=1';
1 row in set, 1 warning (0.00 sec)
mysql> SHOW WARNINGS\G
+---------+------+---------------------------------------------------------------------------------------------------------+
| Level | Code | Message |
+---------+------+---------------------------------------------------------------------------------------------------------+
| Warning | 1296 | Got error 4503 'Table property is FRAGMENT_COUNT_TYPE=ONE_PER_LDM_PER_NODE but not in comment' from NDB |
+---------+------+---------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
The warning is issued because READ_ONLY=1
requires that the table's fragment count type is (or be set
to) ONE_PER_LDM_PER_NODE_GROUP
;
NDB
sets this automatically in such cases.
You can check that the ALTER TABLE
statement
has the desired effect using SHOW CREATE
TABLE
:
mysql> SHOW CREATE TABLE fish\G
*************************** 1. row ***************************
Table: fish
Create Table: 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 (`id`),
UNIQUE KEY `uk` (`name`)
) ENGINE=ndbcluster DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
COMMENT='NDB_TABLE=READ_BACKUP=1,FULLY_REPLICATED=1'
1 row in set (0.01 sec)
Because FRAGMENT_COUNT_TYPE
was not set
explicitly, its value is not shown in the comment text printed
by SHOW CREATE TABLE
.
ndb_desc, however, displays the updated value
for this attribute. The Table options
column
shows the binary properties just enabled. You can see this in
the output shown here (emphasized text):
$> ./ndb_desc -c localhost fish -d test -p
-- fish --
Version: 4
Fragment type: HashMapPartition
K Value: 6
Min load factor: 78
Max load factor: 80
Temporary table: no
Number of attributes: 4
Number of primary keys: 1
Length of frm data: 380
Max Rows: 0
Row Checksum: 1
Row GCI: 1
SingleUserMode: 0
ForceVarPart: 1
PartitionCount: 1
FragmentCount: 1
FragmentCountType: ONE_PER_LDM_PER_NODE_GROUP
ExtraRowGciBits: 0
ExtraRowAuthorBits: 0
TableStatus: Retrieved
Table options: readbackup, fullyreplicated
HashMap: DEFAULT-HASHMAP-3840-1
-- Attributes --
id Int PRIMARY KEY DISTRIBUTION KEY AT=FIXED ST=MEMORY AUTO_INCR
name Varchar(20;latin1_swedish_ci) NOT NULL AT=SHORT_VAR ST=MEMORY DYNAMIC
length_mm Int NOT NULL AT=FIXED ST=MEMORY DYNAMIC
weight_gm Int NOT NULL AT=FIXED ST=MEMORY DYNAMIC
-- Indexes --
PRIMARY KEY(id) - UniqueHashIndex
PRIMARY(id) - OrderedIndex
uk(name) - OrderedIndex
uk$unique(name) - UniqueHashIndex
-- Per partition info --
Partition Row count Commit count Frag fixed memory Frag varsized memory Extent_space Free extent_space
For more information about these table properties, see Section 15.1.20.12, “Setting NDB Comment Options”.
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 25.6.11.1, “NDB Cluster Disk Data Objects”, as well as Section 15.1.16, “CREATE LOGFILE GROUP Statement”, and Section 15.1.21, “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):
DROP TABLE IF EXISTS fish;
CREATE TABLE fish (
id INT NOT NULL AUTO_INCREMENT,
name VARCHAR(20) NOT NULL,
length_mm INT NOT NULL,
weight_gm INT NOT NULL,
PRIMARY KEY pk (id),
UNIQUE KEY uk (name)
) TABLESPACE ts_1 STORAGE DISK
ENGINE=NDB;
INSERT INTO fish VALUES
(NULL, 'guppy', 35, 2), (NULL, 'tuna', 2500, 150000),
(NULL, 'shark', 3000, 110000), (NULL, 'manta ray', 1500, 50000),
(NULL, 'grouper', 900, 125000), (NULL ,'puffer', 250, 2500);
When run against this version of the table, ndb_desc displays the following output:
$> ./ndb_desc -c localhost fish -d test -p
-- fish --
Version: 1
Fragment type: HashMapPartition
K Value: 6
Min load factor: 78
Max load factor: 80
Temporary table: no
Number of attributes: 4
Number of primary keys: 1
Length of frm data: 1001
Max Rows: 0
Row Checksum: 1
Row GCI: 1
SingleUserMode: 0
ForceVarPart: 1
PartitionCount: 2
FragmentCount: 2
PartitionBalance: FOR_RP_BY_LDM
ExtraRowGciBits: 0
ExtraRowAuthorBits: 0
TableStatus: Retrieved
Table options: readbackup
HashMap: DEFAULT-HASHMAP-3840-2
Tablespace id: 16
Tablespace: ts_1
-- Attributes --
id Int PRIMARY KEY DISTRIBUTION KEY AT=FIXED ST=MEMORY AUTO_INCR
name Varchar(80;utf8mb4_0900_ai_ci) NOT NULL AT=SHORT_VAR ST=MEMORY
length_mm Int NOT NULL AT=FIXED ST=DISK
weight_gm Int NOT NULL AT=FIXED ST=DISK
-- Indexes --
PRIMARY KEY(id) - UniqueHashIndex
PRIMARY(id) - OrderedIndex
uk(name) - OrderedIndex
uk$unique(name) - UniqueHashIndex
-- 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
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.
Tablespace id
and
Tablespace
are also displayed for Disk Data
tables.
For fully replicated tables, ndb_desc shows
only the nodes holding primary partition fragment replicas;
nodes with copy fragment replicas (only) are ignored. You can
obtain such information, using the mysql
client, from the
table_distribution_status
,
table_fragments
,
table_info
, and
table_replicas
tables in the
ndbinfo
database.
All options that can be used with ndb_desc are shown in the following table. Additional descriptions follow the table.
--auto-inc
,-a
Show the next value for a table's
AUTO_INCREMENT
column, if it has one.--blob-info
,-b
Include information about subordinate
BLOB
andTEXT
columns.Use of this option also requires the use of the
--extra-partition-info
(-p
) option.-
Command-Line Format --character-sets-dir=path
Directory containing character sets.
-
Command-Line Format --connect-retries=#
Type Integer Default Value 12
Minimum Value 0
Maximum Value 12
Number of times to retry connection before giving up.
-
Command-Line Format --connect-retry-delay=#
Type Integer Default Value 5
Minimum Value 0
Maximum Value 5
Number of seconds to wait between attempts to contact management server.
-
Command-Line Format --connect-string=connection_string
Type String Default Value [none]
Same as
--ndb-connectstring
. --context
,-x
Show additional contextual information for the table such as schema, database name, table name, and the table's internal ID.
-
Command-Line Format --core-file
Write core file on error; used in debugging.
Specify the database in which the table should be found.
-
Command-Line Format --defaults-extra-file=path
Type String Default Value [none]
Read given file after global files are read.
-
Command-Line Format --defaults-file=path
Type String Default Value [none]
Read default options from given file only.
-
Command-Line Format --defaults-group-suffix=string
Type String Default Value [none]
Also read groups with concat(group, suffix).
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.
-
Command-Line Format --help
Display help text and exit.
-
Command-Line Format --login-path=path
Type String Default Value [none]
Read given path from login file.
-
Command-Line Format --no-login-paths
Skips reading options from the login path file.
-
Command-Line Format --ndb-connectstring=connection_string
Type String Default Value [none]
Set connect string for connecting to ndb_mgmd. Syntax:
[nodeid=
. Overrides entries inid
;][host=]hostname
[:port
]NDB_CONNECTSTRING
andmy.cnf
. -
Command-Line Format --ndb-mgm-tls=level
Type Enumeration Default Value relaxed
Valid Values relaxed
strict
Sets the level of TLS support required to connect to the management server; one of
relaxed
orstrict
.relaxed
(the default) means that a TLS connection is attempted, but success is not required;strict
means that TLS is required to connect. -
Command-Line Format --ndb-mgmd-host=connection_string
Type String Default Value [none]
Same as
--ndb-connectstring
. -
Command-Line Format --ndb-nodeid=#
Type Integer Default Value [none]
Set node ID for this node, overriding any ID set by
--ndb-connectstring
. --ndb-optimized-node-selection
Command-Line Format --ndb-optimized-node-selection
Enable optimizations for selection of nodes for transactions. Enabled by default; use
--skip-ndb-optimized-node-selection
to disable.-
Command-Line Format --ndb-tls-search-path=list
Type Path name Default Value (Unix) $HOME/ndb-tls
Default Value (Windows) $HOMEDIR/ndb-tls
Specify a list of directories to search for a CA file. On Unix platforms, the directory names are separated by colons (
:
); on Windows systems, the semicolon character (;
) is used as the separator. A directory reference may be relative or absolute; it may contain one or more environment variables, each denoted by a prefixed dollar sign ($
), and expanded prior to use.Searching begins with the leftmost named directory and proceeds from left to right until a file is found. An empty string denotes an empty search path, which causes all searches to fail. A string consisting of a single dot (
.
) indicates that the search path limited to the current working directory.If no search path is supplied, the compiled-in default value is used. This value depends on the platform used: On Windows, this is
\ndb-tls
; on other platforms (including Linux), it is$HOME/ndb-tls
. This can be overridden by compiling NDB Cluster using-DWITH_NDB_TLS_SEARCH_PATH
. -
Command-Line Format --no-defaults
Do not read default options from any option file other than login file.
-
Command-Line Format --print-defaults
Print program argument list and exit.
--retries=
,#
-r
Try to connect this many times before giving up. One connect attempt is made per second.
--table=
,tbl_name
-t
Specify the table in which to look for an index.
--unqualified
,-u
Use unqualified table names.
-
Command-Line Format --usage
Display help text and exit; same as
--help
. -
Command-Line Format --version
Display version information and exit.
Table indexes listed in the output are ordered by ID.