transaction_read_only

Description

transaction_read_only specifies whether to enable just read-only transactions.

Privilege requirements

• Query variables

  • Global level

    Both the sys tenant and all user tenants can view the values of Global variables by using the SHOW VARIABLES statement or the SYS.TENANT_VIRTUAL_GLOBAL_VARIABLE (Oracle mode) or information_schema.GLOBAL_VARIABLES (MySQL mode) view.

  • Session level

    In Oracle mode, you can use the SHOW VARIABLES statement or the SYS.TENANT_VIRTUAL_SESSION_VARIABLE view to query session system variables in the sys and user tenants. In MySQL mode, you can use the SHOW VARIABLES statement or the information_schema.SESSION_VARIABLES view.

• Modify variables

  • Global level

    • The sys tenant can modify the values of Global system variables.

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

    • In V4.x, starting with V4.2.0, you must grant the ALTER SYSTEM privilege to an Oracle user tenant so that the tenant can modify the values of global system variables.

  • Session level

    Users of the sys and all user tenants can directly modify the session system variables of their own tenants.

Attributes

Description

When the transaction_read_only variable is set to True, DML statements cannot be executed.

Examples

Set to TRUE to allow nonread-only transactions.

• Session level

  obclient> SET transaction_read_only = False;
  

• Global level

  obclient> SET GLOBAL transaction_read_only = False;