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system-variable: the value of ‘tidb_service_scope’ becomes case-insensitive in v9.0.0 and v8.5.6 #22545

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system-variable: the value of ‘tidb_service_scope’ becomes case-insensitive in v9.0.0 and v8.5.6 #22545

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Update system-variables.md
Frank945946 Mar 9, 2026
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10 changes: 5 additions & 5 deletions system-variables.md
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Expand Up @@ -5758,7 +5758,7 @@ SHOW WARNINGS;
- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No
- Type: String
- Default value: ""
- Optional value: a string with a length of up to 64 characters. Valid characters include digits `0-9`, letters `a-zA-Z`, underscores `_`, and hyphens `-`.
- Optional value: a string with a length of up to 64 characters. Valid characters include digits `0-9`, letters `a-zA-Z`, underscores `_`, and hyphens `-`. Starting from v8.5.6 and v9.0.0, the value of this variable is case-insensitive. TiDB converts the input value to lowercase for storage and comparison.
- This variable is an instance-level system variable. You can use it to control the service scope of each TiDB node under the [TiDB Distributed eXecution Framework (DXF)](/tidb-distributed-execution-framework.md). The DXF determines which TiDB nodes can be scheduled to execute distributed tasks based on the value of this variable. For specific rules, see [Task scheduling](/tidb-distributed-execution-framework.md#task-scheduling).

### tidb_session_alias <span class="version-mark">New in v7.4.0</span>
Expand Down Expand Up @@ -5868,7 +5868,7 @@ Query OK, 0 rows affected, 1 warning (0.00 sec)
>
> If the character check is skipped, TiDB might fail to detect invalid UTF-8 characters written by the application, cause decoding errors when `ANALYZE` is executed, and introduce other unknown encoding issues. If your application cannot guarantee the validity of the written string, it is not recommended to skip the character check.

### tidb_slow_log_max_per_sec <span class="version-mark">New in v9.0.0</span>
### tidb_slow_log_max_per_sec <span class="version-mark">New in v8.5.6 and v9.0.0</span>

- Scope: GLOBAL
- Persists to cluster: Yes
Expand All @@ -5879,9 +5879,9 @@ Query OK, 0 rows affected, 1 warning (0.00 sec)
- This variable controls the maximum number of slow query log entries that can be written per TiDB node per second.
- A value of `0` means there is no limit on the number of slow query log entries written per second.
- A value greater than `0` means TiDB writes at most the specified number of slow query log entries per second. Any excess log entries are discarded and not written to the slow query log file.
- This variable is often used with [`tidb_slow_log_rules`](#tidb_slow_log_rules-new-in-v900) to prevent excessive slow query logs from being generated under high-workload conditions.
- This variable is often used with [`tidb_slow_log_rules`](#tidb_slow_log_rules-new-in-v856-and-v900) to prevent excessive slow query logs from being generated under high-workload conditions.

### tidb_slow_log_rules <span class="version-mark">New in v9.0.0</span>
### tidb_slow_log_rules <span class="version-mark">New in v8.5.6 and v9.0.0</span>

- Scope: SESSION | GLOBAL
- Persists to cluster: Yes
Expand All @@ -5892,7 +5892,7 @@ Query OK, 0 rows affected, 1 warning (0.00 sec)

> **Tip:**
>
> After enabling `tidb_slow_log_rules`, it is recommended to also configure [`tidb_slow_log_max_per_sec`](#tidb_slow_log_max_per_sec-new-in-v900) to limit the slow query log output rate and prevent rule-based slow query logging from being triggered too frequently.
> After enabling `tidb_slow_log_rules`, it is recommended to also configure [`tidb_slow_log_max_per_sec`](#tidb_slow_log_max_per_sec-new-in-v856-and-v900) to limit the slow query log output rate and prevent rule-based slow query logging from being triggered too frequently.

### tidb_slow_log_threshold

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