From 925c8c91c75c5297dbd57f7c49abc95c3f536c6b Mon Sep 17 00:00:00 2001 From: Ti Chi Robot Date: Thu, 21 Dec 2023 11:25:54 +0800 Subject: [PATCH] stats: clarify configuration persistence of analyze statement (#13840) (#15821) --- statistics.md | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/statistics.md b/statistics.md index 3d61d68035d6b..782b880aa1f7f 100644 --- a/statistics.md +++ b/statistics.md @@ -460,7 +460,13 @@ The `ANALYZE` configuration persistence feature is disabled by default. To enabl You can use this feature to record the persistence configurations specified in the `ANALYZE` statement when executing the statement manually. Once recorded, the next time TiDB automatically updates statistics or you manually collect statistics without specifying these configuration, TiDB will collect statistics according to the recorded configurations. -When you manually execute the `ANALYZE` statement multiple times with persistence configurations specified, TiDB overwrites the previously recorded persistent configuration using the new configurations specified by the latest `ANALYZE` statement. +To query the configuration persisted on a specific table used for auto analyze operations, you can use the following SQL statement: + +```sql +SELECT sample_num, sample_rate, buckets, topn, column_choice, column_ids FROM mysql.analyze_options opt JOIN information_schema.tables tbl ON opt.table_id = tbl.tidb_table_id WHERE tbl.table_schema = '{db_name}' AND tbl.table_name = '{table_name}'; +``` + +TiDB will overwrite the previously recorded persistent configuration using the new configurations specified by the latest `ANALYZE` statement. For example, if you run `ANALYZE TABLE t WITH 200 TOPN;`, it will set the top 200 values in the `ANALYZE` statement. Subsequently, executing `ANALYZE TABLE t WITH 0.1 SAMPLERATE;` will set both the top 200 values and a sampling rate of 0.1 for auto `ANALYZE` statements, similar to `ANALYZE TABLE t WITH 200 TOPN, 0.1 SAMPLERATE;`. #### Disable ANALYZE configuration persistence