tx_isolation

Description

The tx_isolation variable sets the transaction isolation level. It has the same effect as the transaction_isolation system variable, and setting either is sufficient.

Privilege requirements

• Query variables

  • Global level

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

  • Session level

    The sys tenant and all user tenants can query session system variables by using the SHOW VARIABLES statement or by querying the SYS.TENANT_VIRTUAL_SESSION_VARIABLE view in Oracle mode or the information_schema.SESSION_VARIABLES view in MySQL mode.

• Modify variables

  • Global level

    • The sys tenant can directly change the value of a global system variable.

    • A MySQL user tenant must have the SUPER or ALTER SYSTEM permission to change the value of a global system variable.

    • In V4.x from V4.2.0, Oracle user tenants must have the ALTER SYSTEM privilege to modify the value of global system variables.

  • Session level

    The sys tenant and all user tenants can directly modify the values of system variables in their own tenant sessions.

Attributes

Examples

Set the transaction isolation level to READ-COMMITTED.

• Session level

  obclient> SET tx_isolation = 'READ-COMMITTED';
  

• Global level

  obclient> SET GLOBAL tx_isolation = 'READ-COMMITTED';
  

References

For more information about the transaction isolation levels, see Overview.