Indicates the mode for the transaction.
public enum TransactionMode
Read-only transactions provide guaranteed consistency across several reads, but do not allow writes. Read-only transactions can be configured to read at timestamps in the past. Read-only transactions do not need to be committed and do not take locks.
Locking read-write transactions are the only transaction type that support writing data into Cloud Spanner. These transactions rely on pessimistic locking and, if necessary, two-phase commit. Locking read-write transactions may abort, requiring the application to retry.