Page Types Within an Index Extent

The database server stores index pages into different tblspaces than the table with which it is associated. Within the extent, individual index pages contain different types of data. Index pages can be separated into the following categories:
  • Index pages (root, branch, and leaf pages)

    Index pages contain the index information for the table.

  • Bitmap pages

    Bitmap pages contain control information that monitors the fullness of every page in the extent.

  • Free pages

    Free pages are pages in the extent that are allocated for tblspace use, but whose function has not yet been defined. Free pages can be used to store any kind of information: data, index, TEXT or BYTE data, or bitmap.

All indexes are detached unless you explicitly specify attached indexes.
Important: An extent that is allocated for a table fragment does not contain index pages. Index pages for a fragmented table always reside in a separate tblspace. For more information, see fragmenting table indexes in the chapter on table fragmentation and PDQ in the IBM® Informix® Administrator's Guide.
Figure 1 illustrates the extent structure of an index.
Figure 1. Extent Structure of an Index
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