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cherry pick pingcap#4331 to release-3.1
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Signed-off-by: ti-srebot <[email protected]>
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winoros authored and ti-srebot committed Sep 8, 2020
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Expand Up @@ -103,7 +103,11 @@ ANALYZE INCREMENTAL TABLE TableName PARTITION PartitionNameList INDEX [IndexName

当某个表 `tbl` 的修改行数与总行数的比值大于 `tidb_auto_analyze_ratio`,并且当前时间在 `tidb_auto_analyze_start_time``tidb_auto_analyze_end_time` 之间时,TiDB 会在后台执行 `ANALYZE TABLE tbl` 语句自动更新这个表的统计信息。

在查询语句执行时,TiDB 会以 `feedback-probability` 的概率收集反馈信息,并将其用于更新直方图和 Count-Min Sketch。`feedback-probability` 可通过配置文件修改,其默认值是 `0.0`
在查询语句执行时,TiDB 会以 `feedback-probability` 的概率收集反馈信息,并将其用于更新直方图和 Count-Min Sketch。可通过配置文件修改 `feedback-probability`,其默认值是 `0.05`。设置成 `0.0` 可以关闭这个功能。

> **注意:**
>
> 在配置文件中如果将 `feedback-probability` 设置为 `0` 会导致设置失败并报错。需要设置成 `0.0` 才可以关闭 `feedback-probability`
### 控制 ANALYZE 并发度

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