Disk-storage information

Disk-storage information helps the smart-large-object optimizer of the database server determine how to manage the smart large object most efficiently on disk. The smart-large-object optimizer manages the allocation of and access to smart large objects in an sbspace.

Each smart-large-object has the following disk-storage information:

Allocation-extent information
An allocation extent is a collection of contiguous bytes within an sbspace that the smart-large-object optimizer allocates to the smart large object at one time. Information about allocation extents is as follows:
- Extent size
  The smart-large-object optimizer allocates storage for the smart large object in the amount of the extent size.
- Next-extent size
  The smart-large-object optimizer attempts to allocate an extent as a single, contiguous region in a chunk. If no single extent is large enough for the smart large object, the optimizer uses multiple extents as necessary to satisfy the current write request. After the initial extent fills, the smart-large-object optimizer attempts to allocate another extent of contiguous disk space. This process is called next-extent allocation.
Sizing information
- Average size of smart large objects in the sbspace
- Estimated number of bytes in the new smart large object
- Maximum number of bytes to which the smart large object can grow
Location
The name of the sbspace identifies the location at which to store the smart large object.

The smart-large-object optimizer uses the disk-storage information to determine how best to size, allocate, and manage the extents of the sbspace. It can calculate all disk-storage information for a smart large object except the sbspace name.

Important: For most applications, use the values that the smart-large-object optimizer calculates for the disk-storage information.

For special situations, you can set disk-storage information for a smart large object as part of its storage characteristics.