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Document performance_schema.session_connect_attrs system table (#14616) #14749

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Sep 7, 2023
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Document performance_schema.session_connect_attrs system table (#14616) #14749

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Document performance_schema.session_connect_attrs system table
dveeden Aug 25, 2023
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dveeden Aug 28, 2023
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3 changes: 3 additions & 0 deletions TOC-tidb-cloud.md
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- [`USER_PRIVILEGES`](/information-schema/information-schema-user-privileges.md)
- [`VARIABLES_INFO`](/information-schema/information-schema-variables-info.md)
- [`VIEWS`](/information-schema/information-schema-views.md)
- PERFORMANCE_SCHEMA
- [Overview](/performance-schema/performance-schema.md)
- [`SESSION_CONNECT_ATTRS`](/performance-schema/performance-schema-session-connect-attrs.md)
- [Metadata Lock](/metadata-lock.md)
- [Use UUIDs](/best-practices/uuid.md)
- [System Variables](/system-variables.md)
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3 changes: 3 additions & 0 deletions TOC.md
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- [`VARIABLES_INFO`](/information-schema/information-schema-variables-info.md)
- [`VIEWS`](/information-schema/information-schema-views.md)
- [`METRICS_SCHEMA`](/metrics-schema.md)
- PERFORMANCE_SCHEMA
- [Overview](/performance-schema/performance-schema.md)
- [`SESSION_CONNECT_ATTRS`](/performance-schema/performance-schema-session-connect-attrs.md)
- [Metadata Lock](/metadata-lock.md)
- UI
- TiDB Dashboard
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68 changes: 68 additions & 0 deletions performance-schema/performance-schema-session-connect-attrs.md
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---
title: SESSION_CONNECT_ATTRS
summary: Learn the `SESSION_CONNECT_ATTRS` performance_schema table.
---

# SESSION\_CONNECT\_ATTRS

The `SESSION_CONNECT_ATTRS` table provides information about connection attributes. Session attributes are key-value pairs that are sent by the client when establishing a connection.

Common attributes:

| Attribute Name | Example | Description |
|-------------------|---------------|----------------------------|
| `_client_name` | `libmysql` | Client library name |
| `_client_version` | `8.0.33` | Client library version |
| `_os` | `Linux` | Operating System |
| `_pid` | `712927` | Process ID |
| `_platform` | `x86_64` | CPU Architecture |
| `program_name` | `mysqlsh` | Program name |

You can view the columns of the `SESSION_CONNECT_ATTRS` table as follows:

{{< copyable "sql" >}}

```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 | |
+------------------+---------------------+------+-----+---------+-------+
```

You can view the information on session attributes stored in the `SESSION_CONNECT_ATTRS` table as follows:

{{< copyable "sql" >}}

```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 |
+----------------+-----------------+------------+------------------+
```

Fields in the `SESSION_CONNECT_ATTRS` table are described as follows:

* `PROCESSLIST_ID`: Processlist ID of the session.
* `ATTR_NAME`: Attribute name.
* `ATTR_VALUE`: Attribute value.
* `ORDINAL_POSITION`: Ordinal position of the name/value pair.
50 changes: 50 additions & 0 deletions performance-schema/performance-schema.md
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---
title: Performance Schema
summary: TiDB implements the performance_schema for viewing system metadata.
---

# Performance Schema

TiDB implements performance schema tables for MySQL compatibility.

## Tables for MySQL compatibility

| Table Name | Description |
|--------------------------------------------------------------------------------------------------|-----------------------------------------------------------|
| `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) | Provides connection attributes for sessions. |
| `session_status` | |
| `session_variables` | |
| `setup_actors` | |
| `setup_consumers` | |
| `setup_instruments` | |
| `setup_objects` | |

## Tables that are TiDB extensions

| Table Name | Description |
|--------------------------------------------------------------------------------------------------|-----------------------------------------------------------|
| `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` | |