Structure of the metadata area

An sbspace contains a metadata area for each chunk in the sbspace.

As with the chunk header pages, four areas are exclusive to the first chunk in a sbspace: the sbspace descriptor tblspace, the chunk adjunct tblspace, and the level-1 and level-2 archive tblspaces. The tblspace header section contains a tblspace header for each of these tblspaces (notably excluding the tblspace tblspace). Figure 1 shows the layout of the metadata in the single-chunk sbspace.
Figure 1. Structure of the metadata area for a single-chunk sbspace
The figure shows the structure of the metadata area of a single sbspace. The metadata area is represented as a single column divided into rows; the rows are labeled sbspace descriptor tblspace, Chunk adjunct tblspace, Level-1 and Level 2 archive tblspace, Chunk one LO header tblspace, and Chunk one user-data free-list tblspace.

When you specify the sbspace name in the oncheck -ps option, you can display the number of pages allocated and used for each tblspace in the metadata area.

The following items describe how the metadata area grows:
  • The sbspace descriptor tblspace does not grow.
  • The chunk adjunct tblspace grows as chunks are added.
  • The LO header tblspace grows as large objects are added to the chunk.
  • The tblspace for user-data free list grows if free spaces in the chunk are heavily fragmented.

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