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System Architecture 2-125
Data Pages and Data Row Storage
Eventually, a row may outgrow its original storage location. If this occurs, a
forward pointer to the new location of the data row is left at the position
defined by the rowid. The forward pointer is itself a rowid that defines the
page and the location on the page where the data row is now stored. (Refer
to page 2-127 for further information about the role of the forward pointer in
row storage.)
Data Pages and Data Row Storage
The variable length of a data row has consequences for row storage:
■ A page may contain one or more whole rows.
■ A page may contain portions of one or more rows.
■ A page may contain a combination of whole rows and partial rows.
■ An updated row may increase in size and become too long to return
to its original storage location in a row.
The following paragraphs describe the guidelines OnLine follows during
data storage. Refer to page 2-121 for further information about the role of the
slot table in data storage. Refer to page 2-123 for further information about
the role of the rowid in data storage.