tidb: add the description for `tidb_enable_auto_analyze_priority_queu…

…e` (#16730)

statistics.md

@@ -352,6 +352,7 @@ Three system variables related to automatic update of statistics are as follows:
 | [`tidb_auto_analyze_start_time`](/system-variables.md#tidb_auto_analyze_start_time) | `00:00 +0000` | The start time in a day when TiDB can perform automatic update |
 | [`tidb_auto_analyze_end_time`](/system-variables.md#tidb_auto_analyze_end_time)   | `23:59 +0000` | The end time in a day when TiDB can perform automatic update |
 | [`tidb_auto_analyze_partition_batch_size`](/system-variables.md#tidb_auto_analyze_partition_batch_size-new-in-v640) | `1` | The number of partitions that TiDB automatically analyzes when analyzing a partitioned table (that is, when automatically updating statistics on a partitioned table) |
+| [`tidb_enable_auto_analyze_priority_queue`](/system-variables.md#tidb_enable_auto_analyze_priority_queue-new-in-v800) | `ON` | Controls whether to enable the priority queue to schedule the tasks of automatically collecting statistics. When this variable is enabled, TiDB prioritizes collecting statistics for tables that are more valuable to collect, such as newly created indexes and partitioned tables with partition changes. Additionally, TiDB prioritizes tables with lower health scores, placing them at the front of the queue. |
 
 When the ratio of the number of modified rows to the total number of rows of `tbl` in a table is greater than `tidb_auto_analyze_ratio`, and the current time is between `tidb_auto_analyze_start_time` and `tidb_auto_analyze_end_time`, TiDB executes the `ANALYZE TABLE tbl` statement in the background to automatically update the statistics on this table.
 

system-variables.md

@@ -1872,6 +1872,15 @@ mysql> SELECT job_info FROM mysql.analyze_jobs ORDER BY end_time DESC LIMIT 1;
 - Determines whether TiDB automatically updates table statistics as a background operation.
 - This setting was previously a `tidb.toml` option (`performance.run-auto-analyze`), but changed to a system variable starting from TiDB v6.1.0.
 
+### tidb_enable_auto_analyze_priority_queue <span class="version-mark">New in v8.0.0</span>
+
+- Scope: GLOBAL
+- Persists to cluster: Yes
+- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No
+- Type: Boolean
+- Default value: `ON`
+- This variable is used to control whether to enable the priority queue to schedule the tasks of automatically collecting statistics. When this variable is enabled, TiDB prioritizes collecting statistics for tables that are more valuable to collect, such as newly created indexes and partitioned tables with partition changes. Additionally, TiDB prioritizes tables with lower health scores, placing them at the front of the queue.
+
 ### tidb_enable_auto_increment_in_generated
 
 - Scope: SESSION | GLOBAL