A large object (LOB) is a data item that is too large to be directly stored in a database table. The workaround is to store a locator in the database table. The locator points to the actual location of the data item.
The JDBC driver supports the following LOB data types by using streams:
Binary large objects (
BLOBs), which correspond to unstructured binary dataCharacter large objects (
CLOBs), which correspond to character dataNational character large objects (
NCLOBs), which correspond to national character data
LOB behaviors are different from those of other types of streaming data described in this chapter. LOB data is not directly stored in a table. Only the locator is. You can use the locator to manipulate the actual data, including reading and writing data as a stream. Even during the streaming transmission of LOB data, only necessary data is moved on the network. However, during the streaming transmission of LONG or LONG RAW data, all data are moved on the network.
When you query to get one or more BLOB, CLOB, or NCLOB columns, the JDBC driver transfers the data to the client so that the data stream can be accessed.