add system variable tidb_max_auto_analyze_time (#8790) (#8873)

pingcap · Jun 10, 2022 · 8ebb5b2 · 8ebb5b2
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diff --git a/statistics.md b/statistics.md
@@ -446,7 +446,9 @@ Starting from TiDB v6.1.0, the `SHOW ANALYZE STATUS` statement supports showing
 
 `SHOW ANALYZE STATUS` shows the most recent task records only. Starting from TiDB v6.1.0, you can view the history tasks within the last 7 days through the system table `mysql.analyze_jobs`.
 
-When [`tidb_mem_quota_analyze`](/system-variables.md#tidb_mem_quota_analyze-new-in-v610) is set and the automatic analysis task in the TiDB background uses more memory than this threshold, the task will be retried. You can see failed and retried tasks in the output of the `SHOW ANALYZE STATUS` statement.
+When [`tidb_mem_quota_analyze`](/system-variables.md#tidb_mem_quota_analyze-new-in-v610) is set and an automatic `ANALYZE` task running in the TiDB background uses more memory than this threshold, the task will be retried. You can see failed and retried tasks in the output of the `SHOW ANALYZE STATUS` statement.
+
+When [`tidb_max_auto_analyze_time`](/system-variables.md#tidb_max_auto_analyze_time-new-in-v610) is greater than 0 and an automatic `ANALYZE` task running in the TiDB background takes more time than this threshold, the task will be terminated.
 
 ```sql
 mysql> SHOW ANALYZE STATUS [ShowLikeOrWhere];

diff --git a/system-variables.md b/system-variables.md
@@ -546,6 +546,15 @@ MPP is a distributed computing framework provided by the TiFlash engine, which a
 - Default value: `00:00 +0000`
 - This variable is used to restrict the time window that the automatic update of statistics is permitted. For example, to only allow automatic statistics updates between 1 AM and 3 AM, set `tidb_auto_analyze_start_time='01:00 +0000'` and `tidb_auto_analyze_end_time='03:00 +0000'`.
 
+### `tidb_max_auto_analyze_time` <span class="version-mark">New in v6.1.0</span>
+
+- Scope: GLOBAL
+- Persists to cluster: Yes
+- Default value: `43200`
+- Range: `[0, 2147483647]`
+- Unit: seconds
+- This variable is used to specify the maximum execution time of automatic `ANALYZE` tasks. When the execution time of an automatic `ANALYZE` task exceeds the specified time, the task will be terminated. When the value of this variable is `0`, there is no limit to the maximum execution time of automatic `ANALYZE` tasks.
+
 ### tidb_backoff_lock_fast
 
 - Scope: SESSION | GLOBAL