--- sidebar_label: Statistics title: Performance_Schema Database --- TDengine includes a built-in database named `PERFORMANCE_SCHEMA` to provide access to database performance statistics. This document introduces the tables of PERFORMANCE_SCHEMA and their structure. ## PERF_APP Provides information about clients (such as applications) that connect to the cluster. Similar to SHOW APPS. | # | **Column** | **Data Type** | **Description** | | --- | :----------: | ------------ | ------------------------------- | | 1 | app_id | UBIGINT | Client ID | | 2 | ip | BINARY(16) | Client IP address | | 3 | pid | INT | Client process | | 4 | name | BINARY(24) | Client name | | 5 | start_time | TIMESTAMP | Time when client was started | | 6 | insert_req | UBIGINT | Insert requests | | 7 | insert_row | UBIGINT | Rows inserted | | 8 | insert_time | UBIGINT | Time spent processing insert requests in microseconds | | 9 | insert_bytes | UBIGINT | Size of data inserted in byted | | 10 | fetch_bytes | UBIGINT | Size of query results in bytes | | 11 | query_time | UBIGINT | Time spend processing query requests | | 12 | slow_query | UBIGINT | Number of slow queries (greater than or equal to 3 seconds) | | 13 | total_req | UBIGINT | Total requests | | 14 | current_req | UBIGINT | Requests currently being processed | | 15 | last_access | TIMESTAMP | Last update time | ## PERF_CONNECTIONS Provides information about connections to the database. Similar to SHOW CONNECTIONS. | # | **Column** | **Data Type** | **Description** | | --- | :---------: | ------------ | -------------------------------------------------- | | 1 | conn_id | INT | Connection ID | | 2 | user | BINARY(24) | User name | | 3 | app | BINARY(24) | Client name | | 4 | pid | UINT | Client process ID on client device that initiated the connection | | 5 | end_point | BINARY(128) | Client endpoint | | 6 | login_time | TIMESTAMP | Login time | | 7 | last_access | TIMESTAMP | Last update time | ## PERF_QUERIES Provides information about SQL queries currently running. Similar to SHOW QUERIES. | # | **Column** | **Data Type** | **Description** | | --- | :----------: | ------------ | ---------------------------- | | 1 | kill_id | UBIGINT | ID used to stop the query | | 2 | query_id | INT | Query ID | | 3 | conn_id | UINT | Connection ID | | 4 | app | BINARY(24) | Client name | | 5 | pid | INT | Client process ID on client device | | 6 | user | BINARY(24) | User name | | 7 | end_point | BINARY(16) | Client endpoint | | 8 | create_time | TIMESTAMP | Creation time | | 9 | exec_usec | BIGINT | Elapsed time | | 10 | stable_query | BOOL | Whether the query is on a supertable | | 11 | sub_num | INT | Number of subqueries | | 12 | sub_status | BINARY(1000) | Subquery status | | 13 | sql | BINARY(1024) | SQL statement | ## PERF_TOPICS | # | **Column** | **Data Type** | **Description** | | --- | :---------: | ------------ | ------------------------------ | | 1 | topic_name | BINARY(192) | Topic name | | 2 | db_name | BINARY(64) | Database for the topic | | 3 | create_time | TIMESTAMP | Creation time | | 4 | sql | BINARY(1024) | SQL statement used to create the topic | ## PERF_CONSUMERS | # | **Column** | **Data Type** | **Description** | | --- | :------------: | ------------ | ----------------------------------------------------------- | | 1 | consumer_id | BIGINT | Consumer ID | | 2 | consumer_group | BINARY(192) | Consumer group | | 3 | client_id | BINARY(192) | Client ID (user-defined) | | 4 | status | BINARY(20) | Consumer status | | 5 | topics | BINARY(204) | Subscribed topic. Returns one row for each topic. | | 6 | up_time | TIMESTAMP | Time of first connection to TDengine Server | | 7 | subscribe_time | TIMESTAMP | Time of first subscription | | 8 | rebalance_time | TIMESTAMP | Time of first rebalance triggering | ## PERF_SUBSCRIPTIONS | # | **Column** | **Data Type** | **Description** | | --- | :------------: | ------------ | ------------------------ | | 1 | topic_name | BINARY(204) | Subscribed topic | | 2 | consumer_group | BINARY(193) | Subscribed consumer group | | 3 | vgroup_id | INT | Vgroup ID for the consumer | | 4 | consumer_id | BIGINT | Consumer ID | ## PERF_TRANS | # | **Column** | **Data Type** | **Description** | | --- | :--------------: | ------------ | -------------------------------------------------------------- | | 1 | id | INT | ID of the transaction currently running | | 2 | create_time | TIMESTAMP | Creation time | | 3 | stage | BINARY(12) | Transaction stage (redoAction, undoAction, or commit) | | 4 | db1 | BINARY(64) | First database having a conflict with the transaction | | 5 | db2 | BINARY(64) | Second database having a conflict with the transaction | | 6 | failed_times | INT | Times the transaction has failed | | 7 | last_exec_time | TIMESTAMP | Previous time the transaction was run | | 8 | last_action_info | BINARY(511) | Reason for failure on previous run | ## PERF_SMAS | # | **Column** | **Data Type** | **Description** | | --- | :---------: | ------------ | ------------------------------------------- | | 1 | sma_name | BINARY(192) | Time-range-wise SMA name | | 2 | create_time | TIMESTAMP | Creation time | | 3 | stable_name | BINARY(192) | Supertable name | | 4 | vgroup_id | INT | Dedicated vgroup name | ## PERF_STREAMS | # | **Column** | **Data Type** | **Description** | | --- | :----------: | ------------ | --------------------------------------- | | 1 | stream_name | BINARY(64) | Stream name | | 2 | create_time | TIMESTAMP | Creation time | | 3 | sql | BINARY(1024) | SQL statement used to create the stream | | 4 | status | BIANRY(20) | Current status | | 5 | source_db | BINARY(64) | Source database | | 6 | target_db | BIANRY(64) | Target database | | 7 | target_table | BINARY(192) | Target table | | 8 | watermark | BIGINT | Watermark (see stream processing documentation) | | 9 | trigger | INT | Method of triggering the result push (see stream processing documentation) |