ROLLBACK Server Command Options The decision to use in a manual heuristic recovery. If a  --tc-heuristic-recover  option is specified, the server exits regardless of whether manual heuristic recovery is successful. On systems with more than one storage engine capable of two-phase commit, the  ROLLBACK  option is not safe and causes recovery to halt with the following error: [ERROR] --tc-heuristic-recover rollback strategy is not safe on systems with more than one 2-phase-commit-capable storage engine. Aborting crash recovery. • --transaction-isolation= level • --transaction-read-only 757 Command-Line Format --transaction-read-only[={OFF|ON}] System Variable transaction_read_only Scope Global, Session Dynamic Yes SET_VAR  Hint Applies No Type Boolean Command-Line Format --transaction-isolation=name System Variable transaction_isolation Scope Global, Session Dynamic Yes SET_VAR  Hint Applies No Type Enumeration Default Value REPEATABLE-READ Valid Values READ-UNCOMMITTED READ-COMMITTED REPEATABLE-READ SERIALIZABLE Sets the default transaction isolation level. The  level  value can be  READ-UNCOMMITTED ,  READ- COMMITTED ,  REPEATABLE-READ , or  SERIALIZABLE . See Section 13.3.7, “SET TRANSACTION Statement” . The default transaction isolation level can also be set at runtime using the  SET TRANSACTION statement or by setting the  transaction_isolation  system variable.