Hibernate custom type to avoid 'Caused by: java.sql.SQLException: Stream has already been closed'

Question

How do I write a custom Long class to handle long values in Oracle, to avoid the following error?

Caused by: java.sql.SQLException: Stream has already bee

Answer 1

The following doesn't answer the original question 'how to write a custom Long class to handle long values in Oracle' but may be helpful to avoid the 'Stream has already been closed' error when querying Oracle long raw columns.

We faced this error using a legacy database with no chances of changing the column type. We use Spring with hibernate3 session factory and transaction manager. The problem occurred when more than one task were accessing the DAO concurrently. We are using ojdbc14.jar driver and tried a newer one with no luck.

Setting useFetchSizeWithLongColumn = true in the connection properties for the OJDBC driver solved the problem. See the OracleDriver API

THIS IS A THIN ONLY PROPERTY. IT SHOULD NOT BE USED WITH ANY OTHER DRIVERS. If set to "true", the performance when retrieving data in a 'SELECT' will be improved but the default behavior for handling LONG columns will be changed to fetch multiple rows (prefetch size). It means that enough memory will be allocated to read this data. So if you want to use this property, make sure that the LONG columns you are retrieving are not too big or you may run out of memory. This property can also be set as a java property : java -Doracle.jdbc.useFetchSizeWithLongColumn=true myApplication