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Updated default of tidb_stmt_summary_max_sql_length from 4k to 32k #21015

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Updated default of tidb_stmt_summary_max_sql_length from 4k to 32k #21015

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2 changes: 1 addition & 1 deletion sql-statements/sql-statement-show-variables.md
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Expand Up @@ -129,7 +129,7 @@ SHOW GLOBAL VARIABLES LIKE 'tidb%';
| tidb_snapshot | |
| tidb_stmt_summary_history_size | 24 |
| tidb_stmt_summary_internal_query | 0 |
| tidb_stmt_summary_max_sql_length | 4096 |
| tidb_stmt_summary_max_sql_length | 32768 |
| tidb_stmt_summary_max_stmt_count | 3000 |
| tidb_stmt_summary_refresh_interval | 1800 |
| tidb_store_limit | 0 |
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2 changes: 1 addition & 1 deletion statement-summary-tables.md
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Expand Up @@ -122,7 +122,7 @@ select * from employee where id in (...) and salary between ? and ?;
> - 当 SQL digest 被驱逐时，其相关的所有时间段的 summary 数据都会从 `statements_summary` 和 `statements_summary_history` 这两张表中移除。因此，即使一个时间段的 SQL digest 数量没有超过限制，`statements_summary_history` 表中的 SQL digest 数量也可能小于实际的 SQL digest 数量。如果遇到该情况，并且影响了性能，建议调大 `tidb_stmt_summary_max_stmt_count` 的值。
> - 当启用 [`tidb_stmt_summary_enable_persistent`](#持久化-statements-summary) 时，`statements_summary_history` 表中的数据会持久化到磁盘。此时，`tidb_stmt_summary_max_stmt_count` 仅限制 `statements_summary` 表在内存中可存储的 SQL digest 数量；当超出 `tidb_stmt_summary_max_stmt_count` 的限制时，TiDB 仅会从 `statements_summary` 表中驱逐最久未使用的 SQL digest。

- `tidb_stmt_summary_max_sql_length`：字段 `DIGEST_TEXT` 和 `QUERY_SAMPLE_TEXT` 的最大显示长度，默认值是 4096。
- `tidb_stmt_summary_max_sql_length`：字段 `DIGEST_TEXT` 和 `QUERY_SAMPLE_TEXT` 的最大显示长度，默认值是 `32768` (32 KiB)。
- `tidb_stmt_summary_internal_query`：是否统计 TiDB 的内部 SQL。1 代表统计，0 代表不统计，默认不统计。

statement summary 配置示例如下：
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2 changes: 1 addition & 1 deletion system-variables.md
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Expand Up @@ -5223,7 +5223,7 @@ Query OK, 0 rows affected, 1 warning (0.00 sec)
- 是否持久化到集群：是
- 是否受 Hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value) 控制：否
- 类型：整数型
- 默认值：`4096`
- 默认值：`32768` (32 KiB)`
- 范围：`[0, 2147483647]`
- 单位：字节
- 这个变量用来控制 [Statement Summary Tables](/statement-summary-tables.md) 和 [TiDB Dashboard](/dashboard/dashboard-intro.md) 中显示的 SQL 字符串长度。
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