homework-jianmu/docs/en/14-reference/03-taos-sql/23-perf.md

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---
title: Performance Data
description: The Performance_Schema database stores various statistical information in the system
slug: /tdengine-reference/sql-manual/performance-data
---
Starting from TDengine version 3.0, a built-in database called `performance_schema` has been provided, which stores performance-related statistical data. This section details the tables and structures within it.
## PERF_APP
Provides information about applications (clients) that connect to the cluster. You can also use SHOW APPS to query this information.
| # | **Column Name** | **Data Type** | **Description** |
| --- | :-----------------: | ------------ | ------------------------------------- |
| 1 | app_id | UBIGINT | Client ID |
| 2 | ip | BINARY(16) | Client address |
| 3 | pid | INT | Client process ID |
| 4 | name | BINARY(24) | Client name |
| 5 | start_time | TIMESTAMP | Client startup time |
| 6 | insert_req | UBIGINT | Number of insert requests |
| 7 | insert_row | UBIGINT | Number of rows inserted |
| 8 | insert_time | UBIGINT | Processing time of insert requests, in microseconds |
| 9 | insert_bytes | UBIGINT | Number of bytes in insert request message |
| 10 | fetch_bytes | UBIGINT | Number of bytes in query results |
| 11 | query_time | UBIGINT | Processing time for query requests |
| 12 | slow_query | UBIGINT | Number of slow queries (processing time >= 3 seconds) |
| 13 | total_req | UBIGINT | Total number of requests |
| 14 | current_req | UBIGINT | Number of currently processed requests |
| 15 | last_access | TIMESTAMP | Last update time |
## PERF_CONNECTIONS
Provides information about database connections. You can also use SHOW CONNECTIONS to query this information.
| # | **Column Name** | **Data Type** | **Description** |
| --- | :---------------: | ------------ | --------------------------------------------------------- |
| 1 | conn_id | INT | Connection ID |
| 2 | user | BINARY(24) | Username |
| 3 | app | BINARY(24) | Client name |
| 4 | pid | UINT | Process ID of the client that initiated this connection |
| 5 | end_point | BINARY(128) | Client address |
| 6 | login_time | TIMESTAMP | Login time |
| 7 | last_access | TIMESTAMP | Last update time |
## PERF_QUERIES
Provides information about currently executing SQL statements. You can also use SHOW QUERIES to query this information.
| # | **Column Name** | **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) | App name |
| 5 | pid | INT | App process ID on the host |
| 6 | user | BINARY(24) | Username |
| 7 | end_point | BINARY(16) | Client address |
| 8 | create_time | TIMESTAMP | Creation time |
| 9 | exec_usec | BIGINT | Execution time |
| 10 | stable_query | BOOL | Indicates if it is a supertable query |
| 11 | sub_num | INT | Number of subqueries |
| 12 | sub_status | BINARY(1000) | Subquery status |
| 13 | sql | BINARY(1024) | SQL statement |
## PERF_CONSUMERS
| # | **Column Name** | **Data Type** | **Description** |
| --- | :-------------------: | ------------ | ----------------------------------------------------------- |
| 1 | consumer_id | BIGINT | Unique ID of the consumer |
| 2 | consumer_group | BINARY(192) | Consumer group |
| 3 | client_id | BINARY(192) | User-defined string, displayed by specifying client_id when creating the consumer |
| 4 | status | BINARY(20) | Current status of the consumer. Status includes: ready (available), lost (connection lost), rebalancing (vgroup allocation in progress), unknown (unknown state) |
| 5 | topics | BINARY(204) | Subscribed topics. If multiple topics are subscribed, they are displayed in multiple rows |
| 6 | up_time | TIMESTAMP | Time of first connection to taosd |
| 7 | subscribe_time | TIMESTAMP | Time of last subscription initiation |
| 8 | rebalance_time | TIMESTAMP | Time of last rebalance trigger |
## PERF_TRANS
| # | **Column Name** | **Data Type** | **Description** |
| --- | :--------------------: | ------------ | -------------------------------------------------------------- |
| 1 | id | INT | ID of the ongoing transaction |
| 2 | create_time | TIMESTAMP | Creation time of the transaction |
| 3 | stage | BINARY(12) | Current stage of the transaction, usually redoAction, undoAction, commit |
| 4 | db1 | BINARY(64) | Name of database 1 that conflicts with this transaction |
| 5 | db2 | BINARY(64) | Name of database 2 that conflicts with this transaction |
| 6 | failed_times | INT | Total number of times the transaction execution failed |
| 7 | last_exec_time | TIMESTAMP | Last execution time of the transaction |
| 8 | last_action_info | BINARY(511) | Details of the last execution failure of the transaction |
## PERF_SMAS
| # | **Column Name** | **Data Type** | **Description** |
| --- | :---------------: | ------------ | ------------------------------------------- |
| 1 | sma_name | BINARY(192) | Name of the time-range-wise SMA |
| 2 | create_time | TIMESTAMP | Creation time of the SMA |
| 3 | stable_name | BINARY(192) | Name of the supertable to which the SMA belongs |
| 4 | vgroup_id | INT | Name of the exclusive vgroup for the SMA |