Distributed Transactions

While SAP Sybase IQ is enlisted in a distributed transaction, it hands transaction control over to the transaction server, and SAP Sybase IQ ensures that it does not perform any implicit transaction management. The following conditions are imposed automatically by SAP Sybase IQ when it participates in distributed transactions:

• Autocommit is automatically turned off, if it is in use.

• Data definition statements (which commit as a side effect) are disallowed during distributed transactions.

• An explicit COMMIT or ROLLBACK issued by the application directly to SAP Sybase IQ, instead of through the transaction coordinator, generates an error. The transaction is not aborted, however.

• A connection can participate in only a single distributed transaction at a time.

• There must be no uncommitted operations at the time the connection is enlisted in a distributed transaction.

• DTC Isolation Levels
  DTC has a set of isolation levels, which the application server specifies. These isolation levels map to SAP Sybase IQisolation levels as follows:
• Recovery From Distributed Transactions
  If the database server faults while uncommitted operations are pending, it must either rollback or commit those operations on startup to preserve the atomic nature of the transaction.