From 9e466bca5d12ab68f6f859536c08cda8bf43c197 Mon Sep 17 00:00:00 2001 From: ti-srebot <66930949+ti-srebot@users.noreply.github.com> Date: Mon, 14 Sep 2020 14:23:41 +0800 Subject: [PATCH] Change the default value of `feedback-probability` (#3895) (#3904) Signed-off-by: ti-srebot --- statistics.md | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/statistics.md b/statistics.md index 7d2581f8bfab4..56e193b1408bc 100644 --- a/statistics.md +++ b/statistics.md @@ -126,7 +126,11 @@ Three system variables related to automatic update of statistics are as follows: 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 of this table. -When the query is executed, TiDB collects feedback with the probability of `feedback-probability` and uses it to update the histogram and Count-Min Sketch. You can modify the value of `feedback-probability` in the configuration file. The default value is `0.0`. +When the query is executed, TiDB collects feedback with the probability of `feedback-probability` and uses it to update the histogram and Count-Min Sketch. You can modify the value of `feedback-probability` in the configuration file. The default value is `0.05`. You can set the value to `0.0` to disable this feature. + +> **Note:** +> +> If you set the value of `feedback-probability` to `0` in the configuration file, a failure will occur and an error will be reported. To disable `feedback-probability`, you need to set the value to `0.0`. ### Control `ANALYZE` concurrency