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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.

💡 [V2.0.9.1 Version Update]
👉 Added onw system tables: TABLE_DISK_USAGE (Table-level Storage Space Statistics), enhancing cluster maintenance and performance analysis.

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 2.0.8.2

  • 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 V2.0.9.1

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.