Connection Transaction Isolation 

Use

With this function you can manage the transaction isolation level for the connections created by a particular DataSource object. For more information about transaction isolation, see Locks in the Development Manual.

Activities

This function is available in the Additional tab of the JDBC Connector Service runtime control in the Visual Administrator.

To define the transaction isolation level, set the Default Connection Isolation property. You can choose one of the following options:

·        DEFAULT – the isolation level of the database in use

The default isolation level for an Open SQL data source is TRANSACTION_READ_UNCOMMITTED.

·        TRANSACTION_NONE – this level indicates that the database does not support transactions

·        TRANSACTION_READ_UNCOMMITTED – this level enables transactions to read data that is being modified by other transactions before they either commit or roll back

·        TRANSACTION_READ_COMMITTED – this level enables transactions to read data only after the modifying transaction has committed

·        TRANSACTION_REPEATABLE_READ – this level guarantees that the data the transaction reads is not being modified by another transaction and will not change unless the reading transaction modifies it and commits

·        TRANSACTION_SERIALIZABLE – this level guarantees maximum data integrity, since only one transaction run as a single serial operation can both read and modify the data at a time. Other transactions can access the data only after the serializable transaction has committed or rolled back.

Running a transaction as a single serial operation is time-consuming. It is therefore recommended that you avoid using the TRANSACTION_SERIALIZABLE isolation level if speed is important for your system.

The Open SQL for Java framework supports only TRANSACTION_READ_COMMITTED and TRANSACTION_READ_UNCOMMITTED isolation levels for Open SQL data sources.

See also:

Transactions in Open SQL/JDBC (Development Manual)