{// Union field selector can be only one of the following:"singleUse": {object (TransactionOptions)},"id": string,"begin": {object (TransactionOptions)}// End of list of possible types for union field selector.}
Fields
Union field selector. If no fields are set, the default is a single use transaction with strong concurrency. selector can be only one of the following:
Begin a new transaction and execute this read or SQL query in it. The transaction ID of the new transaction is returned in ResultSetMetadata.transaction, which is a Transaction.