Database Autonomy Service:SQL throttling

Throttling messages

After you create an SQL throttling rule, if an application runs an SQL statement that contains all the specified keywords or matches the template, the database system returns a message when throttling is triggered. The message that is returned varies based on the instance version.

Scenarios

Throttling modes

Procedure

1. Log on to the DAS console.

2. In the left-side navigation pane, choose Intelligent O&M Center > Instance Monitoring.

3. On the page that appears, find the database instance that you want to manage and click the instance ID. The instance details page appears.

4. In the navigation pane on the left, click Instance Sessions.

5. On the Session Management page, click SQL Throttling.

6. In the dialog box that appears, click Create Throttling Rule.

7. In the Create Throttling Rule dialog box, configure the parameters based on the database engine.

ApsaraDB RDS for MySQL

Parameter	Description
Throttling Mode	Select a throttling mode as needed.
SQL Type	Select the type of SQL statement. Valid values: SELECT, UPDATE, DELETE, and INSERT. Note This parameter is required if you set Throttling Mode to Keyword Throttling. You can throttle INSERT statements only on the following database engines: ApsaraDB RDS for MySQL 8.0 PolarDB for MySQL 5.7 and 8.0 PolarDB-X 2.0 You cannot throttle INSERT...SELECT... statements.
Database	The database where SQL statements are throttled. Note This parameter is required if you set Throttling Mode to SQL Template Throttling.
Maximum Concurrency	The maximum number of concurrent SQL statements. The minimum value is 0. Note Throttling is triggered when the number of concurrently running SQL statements that meet the policy reaches the maximum concurrency.
Throttling Duration	The effective period of the SQL throttling rule. Important SQL throttling is an emergency measure. Set the duration as needed and disable the rule when it is no longer required.
SQL Keywords	The keywords of the SQL statements to throttle. Note This parameter is required if you set Throttling mode to Keyword throttling. If you set multiple keywords, the throttling rule is triggered only if an SQL statement contains all of the keywords. Separate multiple keywords with tildes (~). The order of keywords does not matter. For example, the original statement is SELECT min(id), max(id) FROM task_event WHERE gmt_modified < '2020-06-21' AND begin_time > '2020-07-09' AND source IN (527) AND id >= 15673 AND id <= 8015673 . The corresponding throttling keywords are SELECT~min~id~max~id~FROM~task_event~WHERE~gmt_modified~AND~begin_time~AND~source~IN~AND~id~AND~id . You cannot set only SELECT, INSERT, UPDATE, DELETE as throttling keywords. Keywords are case-sensitive, but some earlier instance versions are not case-sensitive.
SQL Sample	The sample SQL statement to throttle. Note This parameter is required if you set Throttling mode to SQL template throttling. For complex SQL statements, DAS optimizes the SQL sample but keeps the final SQL template unchanged. The throttling effect is not affected by the optimization. For example, if you enter select name from das where name = `das` and age = 21 limit 20, it is templated to select name from das where name = ? and age = ? limit ?, and then rewritten to select name from das where name = `param0` and age = `param1` limit 20.

ApsaraDB RDS for PostgreSQL

Parameter	Description
Throttling Mode	ApsaraDB RDS for PostgreSQL supports only SQL template throttling.
Database	The database where SQL statements are throttled.
Search Path	The search path for SQL throttling. Note Separate multiple paths with commas (,). The default value is information_schema,public.
Maximum Concurrency	The maximum number of concurrent SQL statements. The minimum value is 0. Note Throttling is triggered when the number of concurrently running SQL statements that meet the policy reaches the maximum concurrency.
Maximum Waiting Count	The maximum number of waiting statements.
Throttling Duration	The effective period of the SQL throttling rule. Important SQL throttling is an emergency measure. Set the duration as needed and disable the rule when it is no longer required.
SQL Sample	The sample SQL statement to throttle. Note This parameter is required if you set Throttling Mode to SQL Template Throttling. For complex SQL statements, DAS templated the SQL sample but keeps the final SQL template unchanged. The throttling effect is not affected by the transformation. For example, if you enter select name from das where name = "das" and age = 21 limit 20, it is templated to select name from das where name = ? and age = ? limit ?, and then rewritten to select name from das where name = "param0" and age = "param1" limit 20.

PolarDB for MySQL

Parameter	Description
Throttling Mode	Select a throttling mode as needed.
SQL Type	Select the type of SQL statement. Valid values: SELECT, UPDATE, DELETE, and INSERT. Note You can throttle INSERT statements only on the following database engines: ApsaraDB RDS for MySQL 8.0 PolarDB for MySQL 5.7 and 8.0 PolarDB-X 2.0 You cannot throttle INSERT...SELECT... statements.
Maximum Concurrency	The maximum number of concurrent SQL statements. The minimum value is 0. Note Throttling is triggered when the number of concurrently running SQL statements that meet the policy reaches the maximum concurrency.
Database	The database where SQL statements are throttled. Note This parameter is required if you set Throttling Mode to SQL Template Throttling.
Throttling Duration	The effective period of the SQL throttling rule. Important SQL throttling is an emergency measure. Set the duration as needed and disable the rule when it is no longer required.
SQL Keywords	The keywords of the SQL statements to throttle. Note This parameter is required if you set Throttling Mode to Keyword Throttling. If you set multiple keywords, the throttling rule is triggered only if an SQL statement contains all of the keywords. Separate multiple keywords with tildes (~). The order of keywords does not matter. For example, the original statement is SELECT min(id), max(id) FROM task_event WHERE gmt_modified < '2020-06-21' AND begin_time > '2020-07-09' AND source IN (527) AND id >= 15673 AND id <= 8015673 . The corresponding throttling keywords are SELECT~min~id~max~id~FROM~task_event~WHERE~gmt_modified~AND~begin_time~AND~source~IN~AND~id~AND~id . You cannot set only SELECT, INSERT, UPDATE, or DELETE as throttling keywords. Keywords are case-sensitive, but some earlier instance versions are not case-sensitive.
SQL Sample	The sample SQL statement to throttle. Note This parameter is required if you set Throttling Mode to SQL Template Throttling. For complex SQL statements, DAS templated the SQL sample but keeps the final SQL template unchanged. The throttling effect is not affected by the transformation. For example, if you enter select name from das where name = "das" and age = 21 limit 20, it is templated to select name from das where name = ? and age = ? limit ?, and then rewritten to select name from das where name = "param0" and age = "param1" limit 20.

PolarDB-X 2.0

Parameter	Description
Throttling Mode	Select a throttling mode as needed.
SQL Type	Select the type of SQL statement. Valid values: SELECT, UPDATE, DELETE, and INSERT. Note You can throttle INSERT statements only on the following database engines: ApsaraDB RDS for MySQL 8.0 PolarDB for MySQL 5.7 and 8.0 PolarDB-X 2.0 You cannot throttle INSERT...SELECT... statements.
Maximum Concurrency	The maximum number of concurrent SQL statements. The minimum value is 0. Note Throttling is triggered when the number of concurrently running SQL statements that meet the policy reaches the maximum concurrency.
Throttling Duration	The effective period of the SQL throttling rule. Important SQL throttling is an emergency measure. Set the duration as needed and disable the rule when it is no longer required.
SQL Keywords	The keywords of the SQL statements to throttle. Note This parameter is required if you set Throttling Mode to Keyword Throttling. If you set multiple keywords, the throttling rule is triggered only if an SQL statement contains all of the keywords. Separate multiple keywords with tildes (~). The order of keywords does not matter. For example, the original statement is SELECT min(id), max(id) FROM task_event WHERE gmt_modified < '2020-06-21' AND begin_time > '2020-07-09' AND source IN (527) AND id >= 15673 AND id <= 8015673 . The corresponding throttling keywords are SELECT~min~id~max~id~FROM~task_event~WHERE~gmt_modified~AND~begin_time~AND~source~IN~AND~id~AND~id . You cannot set only SELECT, INSERT, UPDATE, or DELETE as throttling keywords. Keywords are case-sensitive, but some earlier instance versions are not case-sensitive.
SQL Template ID	The ID of the SQL template to throttle. An ID is an 8-character hexadecimal string. Separate multiple SQL template IDs with commas (,). Note This parameter is required if the instance is PolarDB-X Enterprise Edition and you set Throttling Mode to SQL Template Throttling.
Minimum SQL Running Time	The threshold for the SQL running time. When the running time of an SQL statement exceeds the threshold, the system adds the ID of the SQL template to which the SQL statement belongs to the throttling rule. Note This parameter is required if the instance is PolarDB-X Enterprise Edition and you set Throttling Mode to Execution Time Throttling.
Maximum Number Of Throttled SQL IDs	The maximum number of SQL template IDs that can be throttled based on running time. After this limit is reached, the system no longer creates throttling rules for other SQL statements whose running time exceeds the threshold. Note This parameter is required if the instance is PolarDB-X Enterprise Edition and you set Throttling Mode to Execution Time Throttling.
Database Account For Throttled SQL	The database account to which the throttled SQL statement belongs. Note This parameter is required if you set Throttling Mode to Keyword Throttling or SQL Template Throttling.

8. Click Submit to create the rule.

   After the SQL throttling rule is created, you can view information about the rule on the Running tab. The following table describes the parameters.

   Note

   The parameters vary slightly based on the database engine and throttling mode.

   Parameter	Description
   Throttling Mode	The mode that you selected.
   Throttling Rule	Keyword Throttling: The configuration of the throttling keywords. SQL Template Throttling: The template ID that corresponds to the throttled sample. Execution Time Throttling: The configured running time threshold and the number of SQL statements throttled by template.
   Maximum Concurrency	The maximum number of concurrent SQL statements.
   Maximum Waiting Count	The maximum number of waiting statements configured in the throttling rule. Note This parameter is displayed if the database instance is ApsaraDB RDS for PostgreSQL and Throttling Mode is set to SQL Template Throttling.
   Throttling Duration (minutes)	The effective period of the SQL throttling rule.
   Start Time	The time when the throttling rule was configured to take effect.
   Remaining Time	The remaining time before the throttling rule expires.
   Throttled SQL Sample	The configuration of the throttled SQL sample. Note This parameter is displayed if you set Throttling Mode to SQL Template Throttling.
   Throttling Template ID	The template ID that corresponds to the throttled SQL sample. Note This parameter is displayed if you set Throttling Mode to SQL Template Throttling.
   Status	A running rule has the Enabled status.
   Database	The database where SQL statements are throttled. Note This parameter is displayed if you set Throttling Mode to SQL Template Throttling.
   Search Path	The search path that corresponds to the throttled SQL statement. Note This parameter is displayed if the database instance is ApsaraDB RDS for PostgreSQL and Throttling Mode is set to SQL Template Throttling.
   Number Of Matched SQL Statements	The number of SQL statements that are matched by the throttling rule. Note This parameter is displayed if you set Throttling Mode to SQL Template Throttling.
   Number Of Waiting SQL Statements	The number of SQL statements that are waiting under the throttling rule. Note This parameter is displayed if you set Throttling Mode to SQL Template Throttling.
   Actions	The buttons to Disable or Modify the throttling rule.

References

• Automatic SQL throttling.

• Concurrency control for PolarDB for MySQL.

• Concurrency control for ApsaraDB RDS for MySQL.

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