The SET AUTOCOMMIT ON statement directs the DBMS Server to treat each query as a single-query transaction.

SET AUTOCOMMIT OFF, the default, means an explicit COMMIT or ROLLBACK statement or terminating the session is required to terminate a transaction.

SET AUTOCOMMIT READ auto-commits a transaction that was started in read-only mode.

Transactions are started read only when no transaction is currently started, and:

An OPEN cursor statement does not suffice to determine a read-only transaction, even in the cursor is declared FOR READONLY.

Actian X cursors can nest or overlap, and an updatable cursor might be opened before the first cursor closes.

If AUTOCOMMIT READ is in effect and an updating statement is issued, a multi-statement transaction will be started. You must explicitly end such a transaction with COMMIT or ROLLBACK.

SET AUTOCOMMIT READ can be helpful for Actian X query sessions, as it releases any locks the transaction might be holding. Even a READLOCK=NOLOCK session takes out internal control locks that would be released by the automatic commit.

The SET AUTOCOMMIT statement cannot be issued in an open transaction. For a description multi-statement transaction behavior, see the chapter “Working with Transactions and Handling Errors.”