System Tables

IoTDB has a built-in system database called INFORMATION_SCHEMA, which contains a series of system tables for storing IoTDB runtime information (such as currently executing SQL statements, etc.). Currently, the INFORMATION_SCHEMA database only supports read operations.

1. System Database

• ​Name​: INFORMATION_SCHEMA
• ​Commands​: Read-only, only supports Show databases (DETAILS) / Show Tables (DETAILS) / Use. Other operations will result in an error: "The database 'information_schema' can only be queried."
• ​Attributes​: TTL=INF, other attributes default to null
• ​SQL Example​:

IoTDB> show databases
+------------------+-------+-----------------------+---------------------+---------------------+
|          Database|TTL(ms)|SchemaReplicationFactor|DataReplicationFactor|TimePartitionInterval|
+------------------+-------+-----------------------+---------------------+---------------------+
|information_schema|    INF|                   null|                 null|                 null|
+------------------+-------+-----------------------+---------------------+---------------------+

IoTDB> show tables from information_schema
+-----------------------+-------+
|              TableName|TTL(ms)|
+-----------------------+-------+
|                columns|    INF|
|           config_nodes|    INF|
|         configurations|    INF|
|            connections|    INF|
|        current_queries|    INF|
|             data_nodes|    INF|
|              databases|    INF|
|              functions|    INF|
|               keywords|    INF|
|                  nodes|    INF|
|           pipe_plugins|    INF|
|                  pipes|    INF|
|                queries|    INF|
|queries_costs_histogram|    INF|
|                regions|    INF|
|               services|    INF|
|          subscriptions|    INF|
|       table_disk_usage|    INF|
|                 tables|    INF|
|                 topics|    INF|
|                  views|    INF|
+-----------------------+-------+

2. System Tables

• ​Names​: DATABASES, TABLES, REGIONS, QUERIES, COLUMNS, PIPES, PIPE_PLUGINS, SUBSCRIPTION, TOPICS, VIEWS, MODELS, FUNCTIONS, CONFIGURATIONS, KEYWORDS, NODES, CONFIG_NODES, DATA_NODES , CONNECTIONS, CURRENT_QUERIES, QUERIES_COSTS_HISTOGRAM, SERVICES, TABLE_DISK_USAGE (detailed descriptions in later sections)
• ​Operations​: Read-only, only supports SELECT, COUNT/SHOW DEVICES, DESC. Any modifications to table structure or content are not allowed and will result in an error: "The database 'information_schema' can only be queried."
• ​Column Names​: System table column names are all lowercase by default and separated by underscores (_).

2.1 DATABASES

• Contains information about all databases in the cluster.
• Table structure is as follows:

Column Name	Data Type	Column Type	Description
database	STRING	TAG	Database name
ttl(ms)	STRING	ATTRIBUTE	Data retention time
schema_replication_factor	INT32	ATTRIBUTE	Schema replica count
data_replication_factor	INT32	ATTRIBUTE	Data replica count
time_partition_interval	INT64	ATTRIBUTE	Time partition interval
schema_region_group_num	INT32	ATTRIBUTE	Number of schema region groups
data_region_group_num	INT32	ATTRIBUTE	Number of data region groups

• The query results only display the collection of databases for which you have any permission on the database itself or any table within the database.
• Query Example:

IoTDB> select * from information_schema.databases
+------------------+-------+-------------------------+-----------------------+-----------------------+-----------------------+---------------------+
|          database|ttl(ms)|schema_replication_factor|data_replication_factor|time_partition_interval|schema_region_group_num|data_region_group_num|
+------------------+-------+-------------------------+-----------------------+-----------------------+-----------------------+---------------------+
|information_schema|    INF|                     null|                   null|                   null|                   null|                 null|
|         database1|    INF|                        1|                      1|              604800000|                      0|                    0|
+------------------+-------+-------------------------+-----------------------+-----------------------+-----------------------+---------------------+

2.2 TABLES

• Contains information about all tables in the cluster.
• Table structure is as follows:

Column Name	Data Type	Column Type	Description
database	STRING	TAG	Database name
table_name	STRING	TAG	Table name
ttl(ms)	STRING	ATTRIBUTE	Data retention time
status	STRING	ATTRIBUTE	Status
comment	STRING	ATTRIBUTE	Description/comment

• Note: Possible values for status: USING, PRE_CREATE, PRE_DELETE. For details, refer to the View Tables in Table Management documentation
• The query results only display the collection of tables for which you have any permission.
• Query Example:

IoTDB> select * from information_schema.tables
+------------------+--------------+-----------+------+-------+-----------+
|          database|    table_name|    ttl(ms)|status|comment| table_type|
+------------------+--------------+-----------+------+-------+-----------+
|information_schema|     databases|        INF| USING|   null|SYSTEM VIEW|
|information_schema|        models|        INF| USING|   null|SYSTEM VIEW|
|information_schema| subscriptions|        INF| USING|   null|SYSTEM VIEW|
|information_schema|       regions|        INF| USING|   null|SYSTEM VIEW|
|information_schema|     functions|        INF| USING|   null|SYSTEM VIEW|
|information_schema|      keywords|        INF| USING|   null|SYSTEM VIEW|
|information_schema|       columns|        INF| USING|   null|SYSTEM VIEW|
|information_schema|        topics|        INF| USING|   null|SYSTEM VIEW|
|information_schema|configurations|        INF| USING|   null|SYSTEM VIEW|
|information_schema|       queries|        INF| USING|   null|SYSTEM VIEW|
|information_schema|        tables|        INF| USING|   null|SYSTEM VIEW|
|information_schema|  pipe_plugins|        INF| USING|   null|SYSTEM VIEW|
|information_schema|         nodes|        INF| USING|   null|SYSTEM VIEW|
|information_schema|    data_nodes|        INF| USING|   null|SYSTEM VIEW|
|information_schema|         pipes|        INF| USING|   null|SYSTEM VIEW|
|information_schema|         views|        INF| USING|   null|SYSTEM VIEW|
|information_schema|  config_nodes|        INF| USING|   null|SYSTEM VIEW|
|         database1|        table1|31536000000| USING|   null| BASE TABLE|
+------------------+--------------+-----------+------+-------+-----------+

2.3 REGIONS

• Contains information about all regions in the cluster.
• Table structure is as follows:

Column Name	Data Type	Column Type	Description
region_id	INT32	TAG	Region ID
datanode_id	INT32	TAG	DataNode ID
type	STRING	ATTRIBUTE	Type (SchemaRegion/DataRegion)
status	STRING	ATTRIBUTE	Status (Running,Unknown, etc.)
database	STRING	ATTRIBUTE	Database name
series_slot_num	INT32	ATTRIBUTE	Number of series slots
time_slot_num	INT64	ATTRIBUTE	Number of time slots
rpc_address	STRING	ATTRIBUTE	RPC address
rpc_port	INT32	ATTRIBUTE	RPC port
internal_address	STRING	ATTRIBUTE	Internal communication address
role	STRING	ATTRIBUTE	Role (Leader/Follower)
create_time	TIMESTAMP	ATTRIBUTE	Creation time
tsfile_size_bytes	INT64	ATTRIBUTE	- For​DataRegion with statistics ​​: Total file size of TsFiles. - ForDataRegion without statistics(Unknown):-1. - For​SchemaRegion​:null.

• Only administrators are allowed to perform query operations.
• Query Example:

IoTDB> select * from information_schema.regions
+---------+-----------+------------+-------+---------+---------------+-------------+-----------+--------+----------------+------+-----------------------------+-----------------+
|region_id|datanode_id|        type| status| database|series_slot_num|time_slot_num|rpc_address|rpc_port|internal_address|  role|                  create_time|tsfile_size_bytes|
+---------+-----------+------------+-------+---------+---------------+-------------+-----------+--------+----------------+------+-----------------------------+-----------------+
|        0|          1|SchemaRegion|Running|database1|             12|            0|    0.0.0.0|    6667|       127.0.0.1|Leader|2025-03-31T11:19:08.485+08:00|             null|
|        1|          1|  DataRegion|Running|database1|              6|            6|    0.0.0.0|    6667|       127.0.0.1|Leader|2025-03-31T11:19:09.156+08:00|             3985|
|        2|          1|  DataRegion|Running|database1|              6|            6|    0.0.0.0|    6667|       127.0.0.1|Leader|2025-03-31T11:19:09.156+08:00|             3841|
+---------+-----------+------------+-------+---------+---------------+-------------+-----------+--------+----------------+------+-----------------------------+-----------------+

2.4 QUERIES

• Contains information about all currently executing queries in the cluster. Can also be queried using the SHOW QUERIES syntax.
• Table structure is as follows:

Column Name	Data Type	Column Type	Description
query_id	STRING	TAG	Query ID
start_time	TIMESTAMP	ATTRIBUTE	Query start timestamp (precision matches system precision)
datanode_id	INT32	ATTRIBUTE	DataNode ID that initiated the query
elapsed_time	FLOAT	ATTRIBUTE	Query execution duration (in seconds)
statement	STRING	ATTRIBUTE	SQL statement of the query
user	STRING	ATTRIBUTE	User who initiated the query

• For regular users, the query results only display the queries executed by themselves; for administrators, all queries are displayed.
• Query Example:

IoTDB> select * from information_schema.queries
+-----------------------+-----------------------------+-----------+------------+----------------------------------------+----+
|               query_id|                   start_time|datanode_id|elapsed_time|                               statement|user|
+-----------------------+-----------------------------+-----------+------------+----------------------------------------+----+
|20250331_023242_00011_1|2025-03-31T10:32:42.360+08:00|          1|       0.025|select * from information_schema.queries|root|
+-----------------------+-----------------------------+-----------+------------+----------------------------------------+----+

2.5 COLUMNS

• Contains information about all columns in tables across the cluster
• Table structure is as follows:

Column Name	Data Type	Column Type	Description
database	STRING	TAG	Database name
table_name	STRING	TAG	Table name
column_name	STRING	TAG	Column name
datatype	STRING	ATTRIBUTE	Column data type
category	STRING	ATTRIBUTE	Column category
status	STRING	ATTRIBUTE	Column status
comment	STRING	ATTRIBUTE	Column description

Notes:

• Possible values for status: USING, PRE_DELETE. For details, refer to Viewing Table Columns in Table Management documentation.

• The query results only display the column information of tables for which you have any permission.

• Query Example:

IoTDB> select * from information_schema.columns where database = 'database1'
+---------+----------+------------+---------+---------+------+-------+
| database|table_name| column_name| datatype| category|status|comment|
+---------+----------+------------+---------+---------+------+-------+
|database1|    table1|        time|TIMESTAMP|     TIME| USING|   null|
|database1|    table1|      region|   STRING|      TAG| USING|   null|
|database1|    table1|    plant_id|   STRING|      TAG| USING|   null|
|database1|    table1|   device_id|   STRING|      TAG| USING|   null|
|database1|    table1|    model_id|   STRING|ATTRIBUTE| USING|   null|
|database1|    table1| maintenance|   STRING|ATTRIBUTE| USING|   null|
|database1|    table1| temperature|    FLOAT|    FIELD| USING|   null|
|database1|    table1|    humidity|    FLOAT|    FIELD| USING|   null|
|database1|    table1|      status|  BOOLEAN|    FIELD| USING|   null|
|database1|    table1|arrival_time|TIMESTAMP|    FIELD| USING|   null|
+---------+----------+------------+---------+---------+------+-------+

2.6 PIPES

• Contains information about all pipes in the cluster
• Table structure is as follows:

Column Name	Data Type	Column Type	Description
id	STRING	TAG	Pipe name
creation_time	TIMESTAMP	ATTRIBUTE	Creation time
state	STRING	ATTRIBUTE	Pipe status (RUNNING/STOPPED)
pipe_source	STRING	ATTRIBUTE	Source plugin parameters
pipe_processor	STRING	ATTRIBUTE	Processor plugin parameters
pipe_sink	STRING	ATTRIBUTE	Sink plugin parameters
exception_message	STRING	ATTRIBUTE	Exception message
remaining_event_count	INT64	ATTRIBUTE	Remaining event count (-1if Unknown)
estimated_remaining_seconds	DOUBLE	ATTRIBUTE	Estimated remaining time in seconds (-1if Unknown)

• Only administrators are allowed to perform operations.
• Query Example:

select * from information_schema.pipes
+----------+-----------------------------+-------+--------------------------------------------------------------------------+--------------+-----------------------------------------------------------------------+-----------------+---------------------+---------------------------+
|        id|                creation_time|  state|                                                               pipe_source|pipe_processor|                                                              pipe_sink|exception_message|remaining_event_count|estimated_remaining_seconds|
+----------+-----------------------------+-------+--------------------------------------------------------------------------+--------------+-----------------------------------------------------------------------+-----------------+---------------------+---------------------------+
|tablepipe1|2025-03-31T12:25:24.040+08:00|RUNNING|{__system.sql-dialect=table, source.password=******, source.username=root}|            {}|{format=hybrid, node-urls=192.168.xxx.xxx:6667, sink=iotdb-thrift-sink}|                 |                    0|                        0.0|
+----------+-----------------------------+-------+--------------------------------------------------------------------------+--------------+-----------------------------------------------------------------------+-----------------+---------------------+---------------------------+

2.7 PIPE_PLUGINS

• Contains information about all PIPE plugins in the cluster
• Table structure is as follows:

Column Name	Data Type	Column Type	Description
plugin_name	STRING	TAG	Plugin name
plugin_type	STRING	ATTRIBUTE	Plugin type (Builtin/External)
class_name	STRING	ATTRIBUTE	Plugin's main class name
plugin_jar	STRING	ATTRIBUTE	Plugin's JAR file name (nullfor builtin type)

• Query Example:

IoTDB> select * from information_schema.pipe_plugins
+---------------------+-----------+-------------------------------------------------------------------------------------------------+----------+
|          plugin_name|plugin_type|                                                                                       class_name|plugin_jar|
+---------------------+-----------+-------------------------------------------------------------------------------------------------+----------+
|IOTDB-THRIFT-SSL-SINK|    Builtin|org.apache.iotdb.commons.pipe.agent.plugin.builtin.connector.iotdb.thrift.IoTDBThriftSslConnector|      null|
|   IOTDB-AIR-GAP-SINK|    Builtin|   org.apache.iotdb.commons.pipe.agent.plugin.builtin.connector.iotdb.airgap.IoTDBAirGapConnector|      null|
|      DO-NOTHING-SINK|    Builtin|        org.apache.iotdb.commons.pipe.agent.plugin.builtin.connector.donothing.DoNothingConnector|      null|
| DO-NOTHING-PROCESSOR|    Builtin|        org.apache.iotdb.commons.pipe.agent.plugin.builtin.processor.donothing.DoNothingProcessor|      null|
|    IOTDB-THRIFT-SINK|    Builtin|   org.apache.iotdb.commons.pipe.agent.plugin.builtin.connector.iotdb.thrift.IoTDBThriftConnector|      null|
|         IOTDB-SOURCE|    Builtin|                org.apache.iotdb.commons.pipe.agent.plugin.builtin.extractor.iotdb.IoTDBExtractor|      null|
+---------------------+-----------+-------------------------------------------------------------------------------------------------+----------+

2.8 SUBSCRIPTIONS

• Contains information about all data subscriptions in the cluster
• Table structure is as follows:

Column Name	Data Type	Column Type	Description
topic_name	STRING	TAG	Subscription topic name
consumer_group_name	STRING	TAG	Consumer group name
subscribed_consumers	STRING	ATTRIBUTE	Subscribed consumers

• Only administrators are allowed to perform operations.
• Query Example:

IoTDB> select * from information_schema.subscriptions where topic_name = 'topic_1'
+----------+-------------------+--------------------------------+
|topic_name|consumer_group_name|            subscribed_consumers|
+----------+-------------------+--------------------------------+
|   topic_1|                cg1|[c3, c4, c5, c6, c7, c0, c1, c2]|
+----------+-------------------+--------------------------------+

2.9 TOPICS

• Contains information about all data subscription topics in the cluster
• Table structure is as follows:

Column Name	Data Type	Column Type	Description
topic_name	STRING	TAG	Subscription topic name
topic_configs	STRING	ATTRIBUTE	Topic configuration parameters

• Only administrators are allowed to perform operations.
• Query Example:

IoTDB> select * from information_schema.topics
+----------+----------------------------------------------------------------+
|topic_name|                                                   topic_configs|
+----------+----------------------------------------------------------------+
|     topic|{__system.sql-dialect=table, start-time=2025-01-10T17:05:38.282}|
+----------+----------------------------------------------------------------+

2.10 VIEWS

This system table is available starting from version V2.0.5.

• Contains information about all table views in the database.
• The table structure is as follows:

Column Name	Data Type	Column Category	Description
database	STRING	TAG	Database name
table_name	STRING	TAG	View name
view_definition	STRING	ATTRIBUTE	SQL statement for view creation

• The query results only display the collection of views for which you have any permission.
• Query example:

IoTDB> select * from information_schema.views
+---------+----------+---------------------------------------------------------------------------------------------------------------------------------------+
| database|table_name|                                                                                                                        view_definition|
+---------+----------+---------------------------------------------------------------------------------------------------------------------------------------+
|database1|        ln|CREATE VIEW "ln" ("device" STRING TAG,"model" STRING TAG,"status" BOOLEAN FIELD,"hardware" STRING FIELD) WITH (ttl='INF') AS root.ln.**|
+---------+----------+---------------------------------------------------------------------------------------------------------------------------------------+

2.11 MODELS

This system table is available starting from version V 2.0.5 and has been discontinued since version V 2.0.8.

• Contains information about all models in the database.
• The table structure is as follows:

Column Name	Data Type	Column Category	Description
model_id	STRING	TAG	Model name
model_type	STRING	ATTRIBUTE	Model type (Forecast, Anomaly Detection, Custom)
state	STRING	ATTRIBUTE	Model status (Available/Unavailable)
configs	STRING	ATTRIBUTE	String format of model hyperparameters, consistent with the output of the show command
notes	STRING	ATTRIBUTE	Model description* Built-in model: Built-in model in IoTDB* User-defined model: Custom model

• Query example:

-- Find all built-in forecast models
IoTDB> select * from information_schema.models where model_type = 'BUILT_IN_FORECAST'
+---------------------+-----------------+------+-------+-----------------------+
|             model_id|       model_type| state|configs|                  notes|
+---------------------+-----------------+------+-------+-----------------------+
|       _STLForecaster|BUILT_IN_FORECAST|ACTIVE|   null|Built-in model in IoTDB|
|     _NaiveForecaster|BUILT_IN_FORECAST|ACTIVE|   null|Built-in model in IoTDB|
|               _ARIMA|BUILT_IN_FORECAST|ACTIVE|   null|Built-in model in IoTDB|
|_ExponentialSmoothing|BUILT_IN_FORECAST|ACTIVE|   null|Built-in model in IoTDB|
|         _HoltWinters|BUILT_IN_FORECAST|ACTIVE|   null|Built-in model in IoTDB|
|             _sundial|BUILT_IN_FORECAST|ACTIVE|   null|Built-in model in IoTDB|
+---------------------+-----------------+------+-------+-----------------------+

2.12 FUNCTIONS

This system table is available starting from version V2.0.5.

• Contains information about all functions in the database.
• The table structure is as follows:

Column Name	Data Type	Column Category	Description
function_name	STRING	TAG	Function name
function_type	STRING	ATTRIBUTE	Function type (Built-in/User-defined, Scalar/Aggregation/Table Function)
class_name(udf)	STRING	ATTRIBUTE	Class name if it is a UDF, otherwise null (tentative)
state	STRING	ATTRIBUTE	Availability status

• Query example:

IoTDB> select * from information_schema.functions where function_type='built-in table function'
+--------------+-----------------------+---------------+---------+
|function_name |          function_type|class_name(udf)|    state|
+--------------+-----------------------+---------------+---------+
|      CUMULATE|built-in table function|           null|AVAILABLE|
|       SESSION|built-in table function|           null|AVAILABLE|
|           HOP|built-in table function|           null|AVAILABLE|
|        TUMBLE|built-in table function|           null|AVAILABLE|
|      FORECAST|built-in table function|           null|AVAILABLE|
|     VARIATION|built-in table function|           null|AVAILABLE|
|      CAPACITY|built-in table function|           null|AVAILABLE|
+--------------+-----------------------+---------------+---------+

2.13 CONFIGURATIONS

This system table is available starting from version V2.0.5.

• Contains all configuration properties of the database.
• The table structure is as follows:

Column Name	Data Type	Column Category	Description
variable	STRING	TAG	Configuration property name
value	STRING	ATTRIBUTE	Configuration property value

• Only administrators are allowed to perform operations on this table.
• Query example:

IoTDB> select * from information_schema.configurations
+----------------------------------+-----------------------------------------------------------------+
|                          variable|                                                            value|
+----------------------------------+-----------------------------------------------------------------+
|                       ClusterName|                                                   defaultCluster|
|             DataReplicationFactor|                                                                1|
|           SchemaReplicationFactor|                                                                1|
|  DataRegionConsensusProtocolClass|                      org.apache.iotdb.consensus.iot.IoTConsensus|
|SchemaRegionConsensusProtocolClass|                  org.apache.iotdb.consensus.ratis.RatisConsensus|
|  ConfigNodeConsensusProtocolClass|                  org.apache.iotdb.consensus.ratis.RatisConsensus|
|               TimePartitionOrigin|                                                                0|
|             TimePartitionInterval|                                                        604800000|
|              ReadConsistencyLevel|                                                           strong|
|           SchemaRegionPerDataNode|                                                                1|
|             DataRegionPerDataNode|                                                                0|
|                     SeriesSlotNum|                                                             1000|
|           SeriesSlotExecutorClass|org.apache.iotdb.commons.partition.executor.hash.BKDRHashExecutor|
|         DiskSpaceWarningThreshold|                                                             0.05|
|                TimestampPrecision|                                                               ms|
+----------------------------------+-----------------------------------------------------------------+

2.14 KEYWORDS

This system table is available starting from version V2.0.5.

• Contains all keywords in the database.
• The table structure is as follows:

Column Name	Data Type	Column Category	Description
word	STRING	TAG	Keyword
reserved	INT32	ATTRIBUTE	Whether it is a reserved word (1 = Yes, 0 = No)

• Query example:

IoTDB> select * from information_schema.keywords limit 10
+----------+--------+
|      word|reserved|
+----------+--------+
|    ABSENT|       0|
|ACTIVATION|       1|
|  ACTIVATE|       1|
|       ADD|       0|
|     ADMIN|       0|
|     AFTER|       0|
|   AINODES|       1|
|       ALL|       0|
|     ALTER|       1|
|   ANALYZE|       0|
+----------+--------+

2.15 NODES

This system table is available starting from version V2.0.5.

• Contains information about all nodes in the database cluster.
• The table structure is as follows:

Column Name	Data Type	Column Category	Description
node_id	INT32	TAG	Node ID
node_type	STRING	ATTRIBUTE	Node type
status	STRING	ATTRIBUTE	Node status
internal_address	STRING	ATTRIBUTE	Internal RPC address
internal_port	INT32	ATTRIBUTE	Internal port
version	STRING	ATTRIBUTE	Version number
build_info	STRING	ATTRIBUTE	Commit ID
activate_status (Enterprise Edition only)	STRING	ATTRIBUTE	Activation status

• Only administrators are allowed to perform operations on this table.
• Query example:

IoTDB> select * from information_schema.nodes 
+-------+----------+-------+----------------+-------------+-------+----------+
|node_id| node_type| status|internal_address|internal_port|version|build_info|
+-------+----------+-------+----------------+-------------+-------+----------+
|      0|ConfigNode|Running|       127.0.0.1|        10710|2.0.5.1|   58d685e|
|      1|  DataNode|Running|       127.0.0.1|        10730|2.0.5.1|   58d685e|
+-------+----------+-------+----------------+-------------+-------+----------+

2.16 CONFIG_NODES

This system table is available starting from version V2.0.5.

• Contains information about all ConfigNodes in the cluster.
• The table structure is as follows:

Column Name	Data Type	Column Category	Description
node_id	INT32	TAG	Node ID
config_consensus_port	INT32	ATTRIBUTE	ConfigNode consensus port
role	STRING	ATTRIBUTE	ConfigNode role

• Only administrators are allowed to perform operations on this table.
• Query example:

IoTDB> select * from information_schema.config_nodes 
+-------+---------------------+------+
|node_id|config_consensus_port|  role|
+-------+---------------------+------+
|      0|                10720|Leader|
+-------+---------------------+------+

2.17 DATA_NODES

This system table is available starting from version V2.0.5.

• Contains information about all DataNodes in the cluster.
• The table structure is as follows:

Column Name	Data Type	Column Category	Description
node_id	INT32	TAG	Node ID
data_region_num	INT32	ATTRIBUTE	Number of DataRegions
schema_region_num	INT32	ATTRIBUTE	Number of SchemaRegions
rpc_address	STRING	ATTRIBUTE	RPC address
rpc_port	INT32	ATTRIBUTE	RPC port
mpp_port	INT32	ATTRIBUTE	MPP communication port
data_consensus_port	INT32	ATTRIBUTE	DataRegion consensus port
schema_consensus_port	INT32	ATTRIBUTE	SchemaRegion consensus port

• Only administrators are allowed to perform operations on this table.
• Query example:

IoTDB> select * from information_schema.data_nodes 
+-------+---------------+-----------------+-----------+--------+--------+-------------------+---------------------+
|node_id|data_region_num|schema_region_num|rpc_address|rpc_port|mpp_port|data_consensus_port|schema_consensus_port|
+-------+---------------+-----------------+-----------+--------+--------+-------------------+---------------------+
|      1|              4|                4|    0.0.0.0|    6667|   10740|              10760|                10750|
+-------+---------------+-----------------+-----------+--------+--------+-------------------+---------------------+

2.18 CONNECTIONS

This system table is available starting from version V 2.0.8

• Contains all connections in the cluster.
• The table structure is as follows:

Column Name	Data Type	Column Type	Description
datanode_id	STRING	TAG	DataNode ID
user_id	STRING	TAG	User ID
session_id	STRING	TAG	Session ID
user_name	STRING	ATTRIBUTE	Username
last_active_time	TIMESTAMP	ATTRIBUTE	Last active time
client_ip	STRING	ATTRIBUTE	Client IP address

• Query example:

IoTDB> select * from information_schema.connections;
+-----------+-------+----------+---------+-----------------------------+---------+
|datanode_id|user_id|session_id|user_name|             last_active_time|client_ip|
+-----------+-------+----------+---------+-----------------------------+---------+
|          1|      0|         2|     root|2026-01-21T16:28:54.704+08:00|127.0.0.1|
+-----------+-------+----------+---------+-----------------------------+---------+

2.19 CURRENT_QUERIES

This system table is available starting from version V 2.0.8

• Contains all queries whose execution end time falls within the range [now() - query_cost_stat_window, now()), including currently executing queries. The query_cost_stat_window parameter represents the query cost statistics window. Its default value is 0 and can be configured via the iotdb-system.properties configuration file.
• The table structure is as follows:

Column Name	Data Type	Column Type	Description
query_id	STRING	TAG	Query statement ID
state	STRING	FIELD	Query state: RUNNING indicates executing, FINISHED indicates completed
start_time	TIMESTAMP	FIELD	Query start timestamp (precision matches system timestamp precision)
end_time	TIMESTAMP	FIELD	Query end timestamp (precision matches system timestamp precision). NULL if query is not yet finished
datanode_id	INT32	FIELD	DataNode from which the query was initiated
cost_time	FLOAT	FIELD	Query execution time in seconds. If query is not finished, shows elapsed time
statement	STRING	FIELD	Query SQL / concatenated query request SQL
user	STRING	FIELD	User who initiated the query
client_ip	STRING	FIELD	Client IP address that initiated the query

• Regular users can only view their own queries; administrators can view all queries.
• Query example:

IoTDB> select * from information_schema.current_queries;
+-----------------------+-------+-----------------------------+--------+-----------+---------+------------------------------------------------+----+---------+
|               query_id|  state|                   start_time|end_time|datanode_id|cost_time|                                       statement|user|client_ip|
+-----------------------+-------+-----------------------------+--------+-----------+---------+------------------------------------------------+----+---------+
|20260121_085427_00013_1|RUNNING|2026-01-21T16:54:27.019+08:00|    null|          1|      0.0|select * from information_schema.current_queries|root|127.0.0.1|
+-----------------------+-------+-----------------------------+--------+-----------+---------+------------------------------------------------+----+---------+

2.20 QUERIES_COSTS_HISTOGRAM

This system table is available starting from version V 2.0.8

• Contains a histogram of query execution times within the past query_cost_stat_window period (only statistics for completed SQL queries). The query_cost_stat_window parameter represents the query cost statistics window. Its default value is 0 and can be configured via the iotdb-system.properties configuration file.
• The table structure is as follows:

Column Name	Data Type	Column Type	Description
bin	STRING	TAG	Bucket name: 61 buckets total - [0, 1), [1, 2), [2, 3), ..., [59, 60), 60+
nums	INT32	FIELD	Number of SQL queries in the bucket
datanode_id	INT32	FIELD	DataNode to which this bucket belongs

• Only administrators can execute operations on this table.
• Query example:

IoTDB> select * from information_schema.queries_costs_histogram limit 10
+------+----+-----------+
|   bin|nums|datanode_id|
+------+----+-----------+
| [0,1)|   0|          1|
| [1,2)|   0|          1|
| [2,3)|   0|          1|
| [3,4)|   0|          1|
| [4,5)|   0|          1|
| [5,6)|   0|          1|
| [6,7)|   0|          1|
| [7,8)|   0|          1|
| [8,9)|   0|          1|
|[9,10)|   0|          1|
+------+----+-----------+

2.21 SERVICES

This system table is available starting from version V 2.0.8

• Displays services (MQTT service, REST service) on all active DataNodes (with RUNNING or READ-ONLY status).
• Table structure:

Column Name	Data Type	Column Type	Description
service_name	STRING	TAG	Service Name
datanode_id	INT32	ATTRIBUTE	DataNode ID where service runs
state	STRING	ATTRIBUTE	Service status: RUNNING/STOPPED

• Query example:

IoTDB> SELECT * FROM information_schema.services
+------------+-----------+---------+
|service_name|datanode_id|state    |
+------------+-----------+---------+
|MQTT        |1          |STOPPED  |
|REST        |1          |RUNNING  |
+------------+-----------+---------+

2.22 TABLE_DISK_USAGE

This system table is available since version V2.0.9-beta

Used to display the disk space usage of specified tables (excluding views), including the size of ChunkGroups and the size of Metadata.

Note: Statistics are based on the actual size of data in TsFiles; therefore, deletions made via mods are not considered.

The table structure is shown below:

Column Name	Data Type	Column Type	Description
database	string	Field	Database name
table_name	string	Field	Table name
datanode_id	int32	Field	DataNode node ID
region_id	int32	Field	Region ID
time_partition	int64	Field	Time partition ID
size_in_bytes	int64	Field	Disk space occupied (in bytes)

Query Examples:

-- Query all data;
select * from information_schema.table_disk_usage;

+---------+-------------------+-----------+---------+--------------+-------------+
| database|         table_name|datanode_id|region_id|time_partition|size_in_bytes|
+---------+-------------------+-----------+---------+--------------+-------------+
|database1|             table1|          1|        3|          2864|          867|
|database1|            table11|          1|        3|          2864|            0|
|database1|             table3|          1|        3|          2864|            0|
|database1|             table1|          1|        3|          2865|         1411|
|database1|            table11|          1|        3|          2865|            0|
|database1|             table3|          1|        3|          2865|            0|
|database1|             table1|          1|        3|          2925|          590|
|database1|            table11|          1|        3|          2925|            0|
|database1|             table3|          1|        3|          2925|            0|
|database1|             table1|          1|        4|          2864|          883|
|database1|            table11|          1|        4|          2864|            0|
|database1|             table3|          1|        4|          2864|            0|
|database1|             table1|          1|        4|          2865|         1224|
|database1|            table11|          1|        4|          2865|            0|
|database1|             table3|          1|        4|          2865|            0|
|database1|             table1|          1|        4|          2888|            0|
|database1|            table11|          1|        4|          2888|            0|
|database1|             table3|          1|        4|          2888|          205|
|     etth|   tab_cov_forecast|          1|        8|             0|            0|
|     etth|           tab_real|          1|        8|             0|          963|
|     etth|tab_target_forecast|          1|        8|             0|            0|
|     etth|   tab_cov_forecast|          1|        9|             0|          448|
|     etth|           tab_real|          1|        9|             0|            0|
|     etth|tab_target_forecast|          1|        9|             0|            0|
+---------+-------------------+-----------+---------+--------------+-------------+

-- Specify query conditions;
select * from information_schema.table_disk_usage where region_id = 4 and table_name like '%1';

+---------+----------+-----------+---------+--------------+-------------+
| database|table_name|datanode_id|region_id|time_partition|size_in_bytes|
+---------+----------+-----------+---------+--------------+-------------+
|database1|    table1|          1|        4|          2864|          883|
|database1|   table11|          1|        4|          2864|            0|
|database1|    table1|          1|        4|          2865|         1224|
|database1|   table11|          1|        4|          2865|            0|
|database1|    table1|          1|        4|          2888|            0|
|database1|   table11|          1|        4|          2888|            0|
+---------+----------+-----------+---------+--------------+-------------+

3. Permission Description

• GRANT/REVOKE operations are not supported for the information_schema database or any of its tables.
• All users can view information_schema database details via the SHOW DATABASES statement.
• All users can list system tables via SHOW TABLES FROM information_schema.
• All users can inspect system table structures using the DESC statement.