Document performance_schema.session_connect_attrs system table (#15449)

Author: ran-huang

TOC.md

@@ -916,7 +916,7 @@
     - 系统表
       - [`mysql`](/mysql-schema.md)
       - INFORMATION_SCHEMA
-        - [Overview](/information-schema/information-schema.md)
+        - [概述](/information-schema/information-schema.md)
         - [`ANALYZE_STATUS`](/information-schema/information-schema-analyze-status.md)
         - [`CHECK_CONSTRAINTS`](/information-schema/information-schema-check-constraints.md)
         - [`CLIENT_ERRORS_SUMMARY_BY_HOST`](/information-schema/client-errors-summary-by-host.md)
@@ -974,6 +974,9 @@
         - [`VARIABLES_INFO`](/information-schema/information-schema-variables-info.md)
         - [`VIEWS`](/information-schema/information-schema-views.md)
       - [`METRICS_SCHEMA`](/metrics-schema.md)
+      - PERFORMANCE_SCHEMA
+        - [概述](/performance-schema/performance-schema.md)
+        - [`SESSION_CONNECT_ATTRS`](/performance-schema/performance-schema-session-connect-attrs.md)
     - [元数据锁](/metadata-lock.md)
   - UI
     - TiDB Dashboard

performance-schema/performance-schema-session-connect-attrs.md

@@ -0,0 +1,64 @@
+---
+title: SESSION_CONNECT_ATTRS
+summary: 了解 performance_schema 表 `SESSION_CONNECT_ATTRS`。
+---
+
+# SESSION\_CONNECT\_ATTRS
+
+`SESSION_CONNECT_ATTRS` 表提供了关于连接属性的信息。会话属性是在建立连接时由客户端发送的键值对。
+
+常见属性：
+
+| 属性名 | 示例 | 描述 |
+|-------|-----|------|
+| `_client_name` | `libmysql` | 客户端库名 |
+| `_client_version` | `8.0.33` | 客户端库版本|
+| `_os` | `Linux` | 操作系统 |
+| `_pid` | `712927` | 进程 ID |
+| `_platform` | `x86_64` | CPU 架构 |
+| `program_name` | `mysqlsh` | 程序名  |
+
+你可以通过以下方式查看 `SESSION_CONNECT_ATTRS` 表的列信息：
+
+```sql
+USE performance_schema;
+DESCRIBE session_connect_attrs;
+```
+
+```
++------------------+---------------------+------+-----+---------+-------+
+| Field            | Type                | Null | Key | Default | Extra |
++------------------+---------------------+------+-----+---------+-------+
+| PROCESSLIST_ID   | bigint(20) unsigned | NO   |     | NULL    |       |
+| ATTR_NAME        | varchar(32)         | NO   |     | NULL    |       |
+| ATTR_VALUE       | varchar(1024)       | YES  |     | NULL    |       |
+| ORDINAL_POSITION | int(11)             | YES  |     | NULL    |       |
++------------------+---------------------+------+-----+---------+-------+
+```
+
+你可以通过以下方式查看 `SESSION_CONNECT_ATTRS` 表中存储的会话属性信息：
+
+```sql
+USE performance_schema;
+TABLE SESSION_CONNECT_ATTRS;
+```
+
+```
++----------------+-----------------+------------+------------------+
+| PROCESSLIST_ID | ATTR_NAME       | ATTR_VALUE | ORDINAL_POSITION |
++----------------+-----------------+------------+------------------+
+|        2097154 | _client_name    | libmysql   |                0 |
+|        2097154 | _client_version | 8.1.0      |                1 |
+|        2097154 | _os             | Linux      |                2 |
+|        2097154 | _pid            | 1299203    |                3 |
+|        2097154 | _platform       | x86_64     |                4 |
+|        2097154 | program_name    | mysqlsh    |                5 |
++----------------+-----------------+------------+------------------+
+```
+
+`SESSION_CONNECT_ATTRS` 表的字段描述如下：
+
+* `PROCESSLIST_ID`：会话的 Processlist ID。
+* `ATTR_NAME`：属性名。
+* `ATTR_VALUE`：属性值。
+* `ORDINAL_POSITION`：属性名/属性值对的序号。

performance-schema/performance-schema.md

@@ -0,0 +1,50 @@
+---
+title: Performance Schema
+summary: 了解 TiDB `performance_schema` 系统数据库。
+---
+
+# Performance Schema
+
+TiDB 实现了兼容 MySQL 的 performance schema 表。
+
+## 与 MySQL 兼容的表
+
+| 表名| 描述 |
+| --- | --- |
+| `events_stages_current` |  |
+| `events_stages_history`|  |
+| `events_stages_history_long` |  |
+| `events_statements_current` |  |
+| `events_statements_history` |  |
+| `events_statements_history_long` |  |
+| `events_statements_summary_by_digest` |  |
+| `events_transactions_current` |  |
+| `events_transactions_history` |  |
+| `events_transactions_history_long` |  |
+| `global_status` |  |
+| `prepared_statements_instances` |  |
+| [`session_connect_attrs`](/performance-schema/performance-schema-session-connect-attrs.md) | 为会话提供连接属性。 |
+| `session_status` |  |
+| `session_variables` |  |
+| `setup_actors`  |  |
+| `setup_consumers`  |  |
+| `setup_instruments`|  |
+| `setup_objects` |  |
+
+## TiDB 中的扩展表
+
+| 表名 | 描述 |
+| ------------------------- | ----------- |
+| `pd_profile_allocs` | |
+| `pd_profile_block`  | |
+| `pd_profile_cpu` | |
+| `pd_profile_goroutines`| |
+| `pd_profile_memory` | |
+| `pd_profile_mutex`  | |
+| `tidb_profile_allocs`  | |
+| `tidb_profile_block`| |
+| `tidb_profile_cpu`  | |
+| `tidb_profile_goroutines` | |
+| `tidb_profile_memory`  | |
+| `tidb_profile_mutex`| |
+| `tikv_profile_cpu`  | |