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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.

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|
|          subscriptions|    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 (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 Table

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 Table

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 Table

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 Table

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 Table

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 Table

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 Table

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 Table

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 Table

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 Table

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 Table

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|
+------+----+-----------+

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.