Notes for Using C Driver

A NuoDB_ResultSet type is returned by various functions in the C driver API. There is no need for a client application to create NuoDB_ResultSet types. However, a client application should call NuoDB_ResultSetFree() when a NuoDB_ResultSet is no longer needed.

A NuoDB_ResultSet behaves differently depending on whether the AUTOCOMMIT property is on or off. If autocommit is on, you are limited to one active, valid NuoDB_ResultSet. Associated NuoDB_ResultSetMetaData types and NuoDB_ResultSet types returned from getGeneratedKeys() in NuoDB_Statement can be open at the same time but they have the same lifecycle. That is, they are valid until closed, committed, or another statement is executed by the NuoDB_Statement type. A statement that returns a NuoDB_ResultSet defers committing the transaction. This ensures that iteration over the NuoDB_ResultSet is consistent with the data and the transaction isolation level. Each execution of a statement commits any previously deferred transaction, which closes any associated NuoDB_ResultSet.

If autocommit is off, you can have as many NuoDB_ResultSet types as you need. Each NuoDB_ResultSet must come from a unique NuoDB_Statement type. You cannot have multiple open NuoDB_ResultSet types from the same statement. When a statement is executed, any currently associated NuoDB_ResultSet is closed and it cannot be reopened or reused.

For a client application to use the same type instance in more than one thread, the client must perform its own synchronization, reference counting, and concurrency control. The C driver provides the necessary thread safety only for its internal state and resources.