parallel_min_scan_time_threshold

Description

parallel_min_scan_time_threshold specifies the minimum evaluation execution time for parallel processing of base table scans in the Auto DOP strategy. When the evaluation execution time for base table scans exceeds this threshold, parallel processing is enabled, and a suitable parallel degree is calculated based on this value.

Privilege requirements

• Query variables

  • Global level

    sys tenant and all user tenants can execute the SHOW VARIABLES statement or query the SYS.TENANT_VIRTUAL_GLOBAL_VARIABLE view (Oracle mode) and the information_schema.GLOBAL_VARIABLES view (MySQL mode) to view the values of global system variables.

  • Session level

    sys tenant and all user tenants can execute the SHOW VARIABLES statement or query the SYS.TENANT_VIRTUAL_SESSION_VARIABLE view (Oracle mode) and the information_schema.SESSION_VARIABLES view (MySQL mode) to view the values of session system variables.

• Modify variables

  • Global level

    • sys tenant can directly modify the value of global system variables.

    • MySQL user tenants must have the SUPER or ALTER SYSTEM privilege to modify the value of global system variables.

    • Oracle user tenants must have the ALTER SYSTEM privilege to modify the value of global system variables.

  • Session level

    sys tenant and all user tenants can directly modify the value of session system variables.

Attributes

Examples

Set the minimum evaluation execution time for parallel processing of base table scans to 100 ms.

• Session level

  obclient> SET parallel_min_scan_time_threshold = 100;
  

• Global level

  obclient> SET GLOBAL parallel_min_scan_time_threshold = 100;