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System Architecture 2-83
OnLine Disk Space Terms and Definitions
Figure 2-11
The logical units of OnLine disk space can be envisioned as overlaying the physical units.
Blob-
page
Initial
extent
Add’tl
extent
Blobspace
tblspace
Database
UNIX
file
Page - Blob
Page - Index
Page - Data
Dbspace
Chunk
Disk unit
Chunk
Chunk
Chunk
Chunk
Add’tl
extent
Several rules of OnLine space allocation are illustrated here. The chunks that compose a dbspace (or blobspace) need not
be contiguous. A single dbspace can include chunks located in cookedandrawfilespace.A database can contain data stored
in both dbspaces and blobspaces. A tblspace can span chunks, but extents cannot. The tblspace is a logical concept that
embraces all data that is allocated to a specific table, including regular data and index pages. Pages that store blobs within
a blobspace can be larger than the pages that store blobs within a dbspace.