Understanding Smart Large Objects

A smart large object is a large object with the following features:

• A smart large object can hold a very large amount of data.

  Currently, a single smart large object can hold up to four terabytes of data. This data is stored in a separate disk space called an sbspace.

• A smart large object is recoverable.

  The database server can log changes to smart large objects and therefore can recover smart-large-object data in the event of a system or hardware failure. Logging of smart large objects is not the default behavior.

• A smart large object supports random access to its data.

  Access to a simple large object (BYTE or TEXT) is on an "all or nothing" basis; that is, the database server returns all of the simple-large-object data that you request at one time. With smart large objects, you can seek to a desired location and read or write the desired number of bytes.

• You can customize storage characteristics of a smart large object.

  When you create a smart large object, you can specify storage characteristics for the smart large object, such as the following characteristics:

  • Whether the database server logs the smart large object in accordance with the current database logging mode
  • Whether the database server keeps track of the last time the smart large object was accessed
  • Whether the database server uses page headers to detect data corruption

The rest of this section describes the parts of a smart large object and the information that the database server keeps about a smart large object.