Large Object Locator Support

SAP jConnect supports large object (LOB) locators. A LOB locator contains a logical pointer to LOB data rather than the data itself, reducing the amount of data that passes through the network between SAP Adaptive Server and its clients.

Server support for LOB locators was introduced in SAP Adaptive Server 15.7.

SAP jConnect accesses LOB data using server-side locators when connected to an SAP Adaptive Server that supports LOB locators and autocommit is turned off. Otherwise, jConnect materializes LOB data at the client side. You can use the complete LOB API with client-side materialized LOB data, however, due to larger data, API performance may be different than when used with LOB locators.

Note: When you are using LOB locators, retrieving a large result set that includes LOB data on each row may impact your application's performance. SAP Adaptive Server returns a LOB locator as part of the result set and, to obtain LOB data, SAP jConnect must cache the remaining result set. SAP recommends that you keep result sets small, or that you enable cursor support to limit the size of data to be cached.

To enable LOB locator support, establish a connection to SAP Adaptive Server with the ENABLE_LOB_LOCATORS connection property set to true. When enabled, client applications can access the locators using the Blob, Clob, and NClob classes from the java.sql package.

Note: When both LOB locators and autocommit are enabled, SAP jConnect automatically switches the LOB locators to client-side-materialized LOB even if the SAP Adaptive Server is capable of supporting LOB locators. This increases the memory used by the client and may degrade performance. Therefore, it is advisable to use LOB locators with autocommit off.

For information about the Blob, Clob, and NClob classes, see the Java documentation.