Oracle C++ Call Interface Programmer's Guide

LOB Classes and Methods
Inline Storage of the LOB Value
Data stored in a LOB is termed the LOB value. The value of an internal LOB may or
may not be stored inline with the other row data. If you do not set DISABLE
STORAGE IN ROW, and if the internal LOB value is less than approximately 4,000
bytes, then the value is stored inline.Otherwise, it is stored outside the row. Since
LOBs are intended to be large objects, inline storage will only be relevant if your
application mixes small and large LOBs.
The LOB value is automatically moved out of the row once it extends beyond
approximately 4,000 bytes.
LOB Locators
Regardless of where the value of the internal LOB is stored, a LOB locator is stored
in the row. You can think of a LOB locator as a pointer to the actual location of the
LOB value. A LOB locator is a locator to an internal LOB while a BFILE locator is a
locator to an external LOB.
■ Internal LOB Locators: For internal LOBs, the LOB column stores a locator to
the LOB value stored in a database tablespace. Each internal LOB column and
attribute for a given row has its own unique LOB locator and a distinct copy of
the LOB value stored in the database tablespace.
■ External LOB Locators: For external LOBs (BFILEs), the LOB column stores a
locator to the external operating system file that houses the BFILE. Each
external LOB column and attribute for a given row has its own BFILE locator.
However, two different rows can contain a BFILE locator that points to the same
operating system file.
LOB Classes and Methods
The classes and methods in Table 5–1are available for LOB operations.
5-4 Oracle C++ Call Interface Programmer’s Guide