Metatables

About metatables

The metatables are tables that are used for checking metadata of data management in GridDB.

[Memo]

• Metatables can only be referred. It is not allowed to register or delete data in the metatables.
• When SELECT data from the metatables, it is necessary to enclose the table name with double quotation marks.

[Points to note]

• The schema of metatables may be changed in future version.

Table information

Table information can be obtained.

Table name

#tables

Schema

Column name	Item	Type
DATABASE_NAME	Database name	STRING
TABLE_NAME	Table name	STRING
TABLE_OPTIONAL_TYPE	Table type COLLECTION / TIMESERIES	STRING
DATA_AFFINITY	Data affinity	STRING
EXPIRATION_TIME	Expiry release elapsed time	INTEGER
EXPIRATION_TIME_UNIT	Expiry release elapsed time unit	STRING
EXPIRATION_DIVISION_COUNT	Expiry release division count	STRING
COMPRESSION_METHOD	Time series compression method	STRING
COMPRESSION_WINDOW_SIZE	Time series compression max period of thinning	INTEGER
COMPRESSION_WINDOW_SIZE_UNIT	Time series compression max period unit of thinning	STRING
PARTITION_TYPE	Partitioning type	STRING
PARTITION_COLUMN	Partitioning key	STRING
PARTITION_INTERVAL_VALUE	Interval value (For interval or interval hash)	INTEGER
PARTITION_INTERVAL_UNIT	Interval unit (For interval of interval hash)	STRING
PARTITION_DIVISION_COUNT	Division count (For hash)	INTEGER
SUBPARTITION_TYPE	Partitioning type ("Hash" for interval hash)	STRING
SUBPARTITION_COLUMN	Partitioning key (for interval hash)	STRING
SUBPARTITION_INTERVAL_VALUE	Interval value	INTEGER
SUBPARTITION_INTERVAL_UNIT	Interval unit	STRING
SUBPARTITION_DIVISION_COUNT	Division count (For interval hash)	INTEGER
EXPIRATION_TYPE	Expiration type ROW / PARTITION	STRING

Index information

Index information can be obtained.

Table name

#index_info

Schema

Column name	Item	Item
DATABASE_NAME	Database name	STRING
TABLE_NAME	Table name	STRING
INDEX_NAME	Index name	STRING
INDEX_TYPE	Index type TREE / HASH / SPATIAL	STRING
ORDINAL_POSITION	Column order in index (sequential number from 1)	SHORT
COLUMN_NAME	Column name	STRING

Partitioning information

Data about partitioned tables can be obtained from this metatable.

Table name

#table_partitions

Schema

Column name	Item	Type
DATABASE_NAME	Database name	STRING
TABLE_NAME	Partitioned table name	STRING
PARTITION_BOUNDARY_VALUE	The lower limit value of each data partition	STRING

Specifications

• Each row represents the information of a data partition.
  • For example, when searching rows of a hash partitioned table in which the division count is 128, the number of rows displayed will be 128.
• In the metatable "#table_partitions", the other columns may be displayed besides the above columns.
• It is required to cast the lower limit value to the partitioning key type for sorting by the lower limit value.

Examples

• Check the number of data partitions

  SELECT COUNT(*) FROM "#table_partitions" WHERE TABLE_NAME='myIntervalPartition';
    
  COUNT(*)
  -----------------------------------
   8703

• Check the lower limit value of each data partition

  SELECT PARTITION_BOUNDARY_VALUE FROM "#table_partitions" WHERE TABLE_NAME='myIntervalPartition'
  ORDER BY PARTITION_BOUNDARY_VALUE;
    
  PARTITION_BOUNDARY_VALUE
  -----------------------------------
  2016-10-30T10:00:00Z
  2017-01-29T10:00:00Z
            :

• Check the lower limit value of each data partitions on the interval partitioned table "myIntervalPartition2" (partitioning key type: INTEGER, interval value: 20000)

  SELECT CAST(PARTITION_BOUNDARY_VALUE AS INTEGER) V FROM "#table_partitions"
  WHERE TABLE_NAME='myIntervalPartition2' ORDER BY V;
    
  PARTITION_BOUNDARY_VALUE
  -----------------------------------
  -5000
  15000
  35000
  55000
    :

View information

View information can be obtained.

Table name

#views

Schema

Column name	Item	Type
DATABASE_NAME	Database name	STRING
VIEW_NAME	View name	STRING
VIEW_DEFINITION	View defining character string	STRING

Information about an SQL in execution

The information about SQL , a query or a job, under execution can be obtained.

Table name

#sqls

Schema

Column name	Item	Type
DATABASE_NAME	Database name	STRING
NODE_ADDRESS	address of the node being processed (system)	STRING
NODE_PORT	The port of the node being processed (system)	INTEGER
START_TIME	Processing start time	TIMESTAMP
APPLICATION_NAME	Application name	STRING
SQL	Query character string	STRING
QUERY_ID	Query ID	STRING
JOB_ID	Job ID	STRING

Information about an event in execution

The information about the event under execution can be obtained.

Table name

#events

Schema

Column name	Item	Type
NODE_ADDRESS	address of the node being processed (system)	STRING
NODE_PORT	The port of the node being processed (system)	INTEGER
START_TIME	Processing start time	TIMESTAMP
APPLICATION_NAME	Application name	STRING
SERVICE_TYPE	Service type (SQL/TRANSACTION/CHECKPOINT/SYNC)	STRING
EVENT_TYPE	Event types (PUT/CP_START/SYNC_START etc.)	STRING
WORKER_INDEX	Thread number of a worker	INTEGER
CLUSTER_PARTITION_INDEX	Cluster partition number	INTEGER

Connection information

The information about the connected connection can be obtained.

Table name

#sockets

Schema

Column name	Item	Type
SERVICE_TYPE	Service type (SQL/TRANSACTION)	STRING
SOCKET_TYPE	Socket type	STRING
NODE_ADDRESS	Connection source node address (viewed from a node)	STRING
NODE_PORT	Connection source node port (viewed from a node)	INTEGER
REMOTE_ADDRESS	Connection destination node address (viewed from a node)	STRING
REMOTE_PORT	Connection destination node port (viewed from a node)	INTEGER
APPLICATION_NAME	Application name	STRING
CREATION_TIME	Socket generation time	TIMESTAMP
DISPATCHING_EVENT_COUNT	Total number of times to start request for event handling	LONG
SENDING_EVENT_COUNT	Total number of times to start event transmission	LONG

the socket types are as follows.

Value	Description
SERVER	TCP connection between servers
CLIENT	TCP connection with a client
MULTICAST	Multicasting socket
NULL	In case currently unidentified during the cases such as connection attempt

Examples

Only in case of TCP connection with a client (socket type: CLIENT), it can be determined whether the connection is waiting for execution.

Specifically, if DISPATCHING_EVENT_COUNT is larger than SENDING_EVENT_COUNT, it can be determine that the possibility is relatively high that the time waiting for execution existed.

SELECT CREATION_TIME, NODE_ADDRESS, NODE_PORT, APPLICATION_NAME FROM "#sockets"
WHERE SOCKET_TYPE='CLIENT' AND DISPATCHING_EVENT_COUNT > SENDING_EVENT_COUNT;

CREATION_TIME             NODE_ADDRESS   NODE_PORT  APPLICATION_NAME
--------------------------------------------------------------------
2019-03-27T11:30:57.147Z  192.168.56.71  20001      myapp
2019-03-27T11:36:37.352Z  192.168.56.71  20001      myapp
          :