ob_table_access_policy

Description

The ob_table_access_policy variable controls the optimizer to prioritize the selection of specific storage formats when generating a base table plan.

Privilege requirements

• Query variables

  • Global level

    sys tenants and user tenants can execute the SHOW VARIABLES statement or view SYS.TENANT_VIRTUAL_GLOBAL_VARIABLE (Oracle mode) and information_schema.GLOBAL_VARIABLES (MySQL mode) to query the value of a global system variable.

  • Session level

    sys tenants and user tenants can execute the SHOW VARIABLES statement or view SYS.TENANT_VIRTUAL_SESSION_VARIABLE (Oracle mode) and information_schema.SESSION_VARIABLES (MySQL mode) to query the value of a session system variable.

• Modify variables

  • Global take effect

    • sys tenants can directly modify the value of a global system variable.

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

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

  • Session take effect

    sys tenants and user tenants can directly modify the value of a session system variable in their own tenant.

Attributes

Examples

The following examples show how to configure the optimizer to prioritize the selection of column-based storage format when generating a base table plan.

• Session take effect

  obclient> SET ob_table_access_policy='COLUMN_STORE';
  

• Global take effect

  obclient> SET GLOBAL ob_table_access_policy='COLUMN_STORE';