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.