From 13cb877e3e73ac03e7a7ee80b2d2d61b351d47cb Mon Sep 17 00:00:00 2001 From: Ran Date: Tue, 19 Apr 2022 15:48:22 +0800 Subject: [PATCH] update statement summary variables scope Signed-off-by: Ran --- statement-summary-tables.md | 7 ------- 1 file changed, 7 deletions(-) diff --git a/statement-summary-tables.md b/statement-summary-tables.md index ffe38de16ad55..1c3ceec09b38a 100644 --- a/statement-summary-tables.md +++ b/statement-summary-tables.md @@ -130,13 +130,6 @@ After the configuration above takes effect, every 30 minutes the `statements_sum The `statements_summary_evicted` table records the recent 24 periods during which SQL statements are evicted from the statement summary. The `statements_summary_evicted` table is updated every 30 minutes. -The system variables above have two scopes: global and session. These scopes work differently from other system variables: - -- After setting the global variable, your setting applies to the whole cluster immediately. -- After setting the session variable, your setting applies to the current TiDB server immediately. This is useful when you debug on a single TiDB server instance. -- The session variable has a higher read priority. The global variable is read only when no session variable is set. -- If you set the session variable to a blank string, the global variable is re-read. - > **Note:** > > The `tidb_stmt_summary_history_size`, `tidb_stmt_summary_max_stmt_count`, and `tidb_stmt_summary_max_sql_length` configuration items affect memory usage. It is recommended that you adjust these configurations based on your needs. It is not recommended to set them too large values.