Smart Large Objects in the Database Server

In the Informix database server, a smart large object has two parts:

• The data, which is stored in an sbspace
• A large-object handle, known as an LO handle, which identifies the location of the smart-large-object data in its sbspace

Suppose you store the picture of an employee as a smart large object. Figure 3 shows how the LO handle contains information about the location of the actual employee picture in the sbspace1_100 sbspace.

Figure 3. Smart Large Object in the Database Server

In Figure 3, the sbspace holds the actual employee image that the LO handle identifies. For more information about the structure of an sbspace, and the onspaces database utility that creates and drops sbspaces, see the IBM Informix: Dynamic Server Administrator's Guide.

Because a smart large object is potentially very large, the database server stores only its LO handle in a database table; it can then use this handle to find the actual data of the smart large object in the sbspace. This arrangement minimizes the table size.

Applications obtain the LO handle from the database and use it to locate the smart-large-object data and to open the smart large object for read and write operations.