Help Center/ TaurusDB/ User Guide/ DBA Assistant/ SQL Analysis and Tunning/ Configuring SQL Throttling
Updated on 2025-09-19 GMT+08:00
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Configuring SQL Throttling

Scenarios

SQL throttling allows you to create rules to control concurrent execution of SQL statements by specifying SQL type, keywords, and maximum concurrency. To maintain better performance at high concurrency, SQL statements that meet the specified SQL type and keyword and exceed the maximum concurrency will not be executed. You can check how many times SQL statements are intercepted by throttling rules.

You can also identify SQL statements that consume the most resources based on the execution duration or number of executions and then create throttling rules for these SQL statements.

Throttling rules will be regenerated for all SELECT, UPDATE, DELETE, and INSERT statements when you add or delete a throttling rule, reboot a node, enable or disable SQL throttling or when a throttling rule expires. The number of concurrent and intercepted requests of the regenerated throttling rules will be cleared and recalculated.

Supported Versions

SQL throttling is only available to TaurusDB instances that meet any of the following requirements:
  • 2.0.28.40 > kernel version ≥ 2.0.28.15 (Throttling rules for SELECT, UPDATE, and DELETE statements are supported.)
  • Kernel version ≥ 2.0.29.1 (Throttling rules for SELECT, UPDATE, and DELETE statements are supported.)
  • Kernel version ≥ 2.0.54.240600 (Throttling rules for SELECT, UPDATE, DELETE, and INSERT statements are supported.)

For details about how to check the kernel version, see How Can I Check the Version of a TaurusDB Instance?

Constraints

Table 1 Constraints on throttling rules

Scenario

Constraint

Adding a SQL throttling rule
  • A single throttling rule can contain a maximum of 128 keywords. Backslashes (\) or null characters (' ') cannot be used as keywords. Spaces at the beginning and end of a keyword and special null characters (such as \'t', \'r', and \'n') will be ignored.
  • A throttling rule cannot end with a tilde (~).
  • If the kernel version of your TaurusDB instance is 2.0.54.240600 or later, the total length of all rules and concurrent requests of SELECT, UPDATE, DELETE, or INSERT statements cannot exceed 4,000 bytes. The length of a single rule cannot exceed 1,000 bytes.
  • If the kernel version of your TaurusDB instance is earlier than 2.0.54.240600, the total length of all rules and concurrent requests of SELECT, UPDATE, or DELETE statements cannot exceed 1,024 bytes.

Matching a SQL throttling rule
  • Keywords in a throttling rule will be matched in sequence. For example, if a rule contains a~and~b, only xxx a>1 and b>2 will be matched. xxx b>2 and a>1 will not be matched.
  • Each SQL throttling rule is applied to only the SQL statements that your database received after the rule is created.
  • If different rules are created for the primary node and read replicas of an instance, the rules still apply to the primary node and read replicas after their roles are switched over.
  • If a SQL statement matches multiple throttling rules, only the most recently added rule is applied.
  • SQL statements that have been executed before a SQL throttling rule is added are not counted.
  • Throttling rules are applied based on SQL statement prefixes. For example, if a throttling rule is SELECT~COUNT~t1, SELECT COUNT(*) FROM t1 and SELECT COUNT(*) FROM t1 LIMIT 1 will both be intercepted.
  • Throttling rules will be regenerated for all SELECT, UPDATE, DELETE, and INSERT statements when you add or delete a throttling rule, reboot a node, enable or disable SQL throttling or when a throttling rule expires. The number of concurrent and intercepted requests of the regenerated throttling rules will be cleared and recalculated.

Recommended rule
  • The creation time of existing throttling rules in the SQL throttling rule list are displayed as the time when the feature for setting validity periods for throttling rules was released. The creation time of new throttling rules will be displayed accurately.
  • SQL statements executed by user root are not included in the recommended rule.
  • If the length of a SQL statement exceeds 1,000 bytes, the SQL statement will be automatically truncated. You need to modify its length when using the recommended rule.
  • The recommended rule is based on the 1,000 longest sessions.

Scenarios not subject to SQL throttling
  • System tables
  • SQL statements not used to query data, such as SELECT SLEEP(xxx);
  • Account root
  • SQL statements in stored procedures, triggers, and functions

Impact of throttling rules
  • If there are too many throttling rules, performance of SELECT, UPDATE, DELETE, and INSERT statements will deteriorate.
  • If SQL throttling is triggered, error "ERROR 1317 (70100): Query execution was interrupted" is reported.

Adding a Throttling Rule

  1. Log in to the management console.
  2. Click in the upper left corner and select a region and project.
  3. Click in the upper left corner of the page and choose Databases > TaurusDB.
  4. On the Instances page, click the instance name.
  5. In the navigation pane, choose DBA Assistant > Historical Diagnosis.
  6. Click SQL Explorer and then SQL Throttling.
  7. On the displayed page, toggle on Enable SQL Throttling.
  8. Click Add Rule. In the displayed dialog box, specify SQL Type, Keyword, and Max. Concurrent Requests.

    Figure 1 Adding a SQL throttling rule

    Table 2 Parameter description

    Parameter

    Description

    SQL Type

    There are four options: SELECT, UPDATE, DELETE, and INSERT.

    Keyword

    A maximum of 128 keywords (case-insensitive) are supported. You can specify keywords in either of the following ways:

    • Manually: Take select~a as an example. select and a are two keywords contained in a SQL throttling rule. The keywords are separated by a tilde (~). In this example, the rule restricts the execution of only the SQL statements containing keywords select and a.
    • Using SQL statements: You can enter a SQL statement and then click Generate Keyword. The generated keywords are for reference only. Exercise caution when using them.

    SQL statements match the keywords from first to last. For example, if one rule contains the keyword a~and~b, the statement *** a>1 and b>2 can match the keyword, but *** b>2 and a>1 cannot.

    Empty characters before and after each keyword will be ignored, for example, spaces, '\n', '\r', and '\t'.

    Max. Concurrent Requests

    If the number of concurrent SQL statements matching the keyword exceeds this limit, the SQL statements will not be executed. The value ranges from 0 to 1000000000.

    Kill existing sessions that match this rule

    If this option is selected, all sessions generated by users subject to this SQL throttling rule will be killed.

    Synchronize rules to other nodes

    If this option is selected, new throttling rules will be synchronized to other nodes of a given instance.

    Setting the validity period for a throttling rule

    The validity period of a rule is the specific timeframe during which the rule is in effect.

    • Permanent: The new SQL throttling rule takes effect permanently.
    • Limited: You need to specify the expiration time for the SQL throttling rule. The validity period starts when the request to add the rule is submitted. The expiration time may be delayed for a maximum of 1 minute.

      The expiration time can be a maximum of two weeks later than the current time.

  9. Confirm the settings and click OK.
  10. In the displayed dialog box, click OK.

Recommended Rule

  1. Log in to the management console.
  2. Click in the upper left corner and select a region and project.
  3. Click in the upper left corner of the page and choose Databases > TaurusDB.
  4. On the Instances page, click the instance name.
  5. In the navigation pane, choose DBA Assistant > Historical Diagnosis.
  6. Click SQL Explorer and then SQL Throttling.
  7. Click Recommended Rule.
  8. In the displayed dialog box, set the query criteria. You can filter top SQL statements by Avg. Duration or Executions.

  9. Click OK.
  10. To throttle a high-load SQL statement, click SQL Throttling in the Operation column. In the displayed dialog box, add a SQL throttling rule. For more information, see Adding a Throttling Rule.

Deleting a Throttling Rule

  1. Log in to the management console.
  2. Click in the upper left corner and select a region and project.
  3. Click in the upper left corner of the page and choose Databases > TaurusDB.
  4. On the Instances page, click the instance name.
  5. In the navigation pane, choose DBA Assistant > Historical Diagnosis.
  6. Click SQL Explorer and then SQL Throttling.
  7. Locate a SQL throttling rule and click Delete in the Operation column.

    Alternatively, select one or more throttling rules and click Delete above the list.

  8. In the displayed dialog box, confirm the throttling rules to be deleted. If you select Synchronize rules to other nodes, the throttling rules of other nodes of a given instance will also be deleted. Click OK.

    Figure 2 Deleting a throttling rule

Parent Topic: SQL Analysis and Tunning