Adding an Overflow Segment

For index-organized tables, it is common, and even recommended, to create an overflow area for row data as part of the overall index-organized table structure. The typical index-organized table that includes an overflow area is structured as follows:

  • B-tree index entry, which includes the following:
    • Primary key columns
    • Some non-key columns depending on PCTTHRESHOLD and INCLUDING clause values specified
    • Physical ROWID pointer to overflow segment
  • Overflow segment, which contains the remaining non-key column values

In a normal B-tree index, the leaf node contains the index column key value, and then the ROWID for the row in the data segment. With index-organized tables, all the non-key column values are stored within ...

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