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 Table Access (UPDATE) Using a B* Tree 

Table access using a B* tree is illustrated using the example of an UPDATE statement.

·        If an UPDATE is performed and the primary key  remains unchanged, only the contents of the table row are changed.

·        If the data length changes, the positions of subsequent entries and their addresses in the position list of the leaf page in the B* tree  are changed.

·        If the key field changes, the UPDATE is executed as a DELETE (see Table Access (DELETE) Using a B* Tree) with a subsequent INSERT (see Table Access (INSERT) Using a B* Tree).

 

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