diff --git a/dashboard/dashboard-slow-query.md b/dashboard/dashboard-slow-query.md
index f8f1db1363bfa..5c78cf2fa48a3 100644
--- a/dashboard/dashboard-slow-query.md
+++ b/dashboard/dashboard-slow-query.md
@@ -59,6 +59,10 @@ Click any item in the list to display detailed execution information of the slow
### SQL
+> **Note:**
+>
+> The maximum length of the query recorded in the `Query` column is limited by the [`tidb_stmt_summary_max_sql_length`](/system-variables.md#tidb_stmt_summary_max_sql_length-new-in-v40) system variable.
+
Click the **Expand** button to view the detailed information of an item. Click the **Copy** button to copy the detailed information to the clipboard.
### Execution plans
diff --git a/information-schema/information-schema-slow-query.md b/information-schema/information-schema-slow-query.md
index 8510aec12ffc5..9678b20f6a25c 100644
--- a/information-schema/information-schema-slow-query.md
+++ b/information-schema/information-schema-slow-query.md
@@ -106,6 +106,8 @@ The output is as follows:
74 rows in set (0.001 sec)
```
+The maximum statement length of the `Query` column is limited by the [`tidb_stmt_summary_max_sql_length`](/system-variables.md#tidb_stmt_summary_max_sql_length-new-in-v40) system variable.
+
## CLUSTER_SLOW_QUERY table
The `CLUSTER_SLOW_QUERY` table provides the slow query information of all nodes in the cluster, which is the parsing result of the TiDB slow log files. You can use the `CLUSTER_SLOW_QUERY` table the way you do with `SLOW_QUERY`. The table schema of the `CLUSTER_SLOW_QUERY` table differs from that of the `SLOW_QUERY` table in that an `INSTANCE` column is added to `CLUSTER_SLOW_QUERY`. The `INSTANCE` column represents the TiDB node address of the row information on the slow query.
@@ -222,9 +224,9 @@ The output is as follows:
| id | estRows | task | access object | operator info |
+----------------------------+----------+-----------+--------------------------+------------------------------------------------------+
| StreamAgg_7 | 1.00 | root | | funcs:count(1)->Column#75 |
-| └─TableReader_13 | 10.00 | root | | data:Selection_12 |
-| └─Selection_12 | 10.00 | cop[tidb] | | eq(INFORMATION_SCHEMA.cluster_slow_query.user, "u1") |
-| └─TableFullScan_11 | 10000.00 | cop[tidb] | table:CLUSTER_SLOW_QUERY | keep order:false, stats:pseudo |
+| └─TableReader_13 | 10.00 | root | | data:Selection_12 |
+| └─Selection_12 | 10.00 | cop[tidb] | | eq(INFORMATION_SCHEMA.cluster_slow_query.user, "u1") |
+| └─TableFullScan_11 | 10000.00 | cop[tidb] | table:CLUSTER_SLOW_QUERY | keep order:false, stats:pseudo |
+----------------------------+----------+-----------+--------------------------+------------------------------------------------------+
4 rows in set (0.00 sec)
```
diff --git a/system-variables.md b/system-variables.md
index 2f606e80e10c3..34a2eb59269f3 100644
--- a/system-variables.md
+++ b/system-variables.md
@@ -4588,7 +4588,18 @@ For details, see [Identify Slow Queries](/identify-slow-queries.md).
- Type: Integer
- Default value: `4096`
- Range: `[0, 2147483647]`
-- This variable is used to control the length of the SQL string in [statement summary tables](/statement-summary-tables.md).
+
+
+
+- This variable is used to control the length of the SQL string in [statement summary tables](/statement-summary-tables.md), the [`SLOW_QUERY`](/information-schema/information-schema-slow-query.md) table, and the [TiDB Dashboard](/dashboard/dashboard-intro.md).
+
+
+
+
+
+- This variable is used to control the length of the SQL string in [statement summary tables](/statement-summary-tables.md) and the [`SLOW_QUERY`](/information-schema/information-schema-slow-query.md) table.
+
+
### tidb_stmt_summary_max_stmt_count New in v4.0