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.
OceanBase Connector/J uses streams to support the following LOB data types:
Binary large object (
BLOB)This data type is used for unstructured binary data.
Character large object (
CLOB)This data type is used for character data.
National character large object (
NCLOB)This data type is used for national character data.
BLOBs, CLOBs, and NCLOBs are permanently stored in database tablespaces. All operations performed on these data types are controlled by transactions.
PL supports the LOB data types. The JDBC API allows you to pass IN parameters to PL stored procedures or functions and retrieve OUT parameters or returned values.
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 use a query to get one or more BLOB, CLOB, or NCLOB columns, OceanBase Connector/J transfers the data to the client so that the data stream can be accessed.