Partially-Indexed Sequential File Organization


For Fully-Indexed File Organisation see page 7.1.5 Fully-Indexed File Organization

Partial indexed sequential file organization is when a sequential file is indexed by keys using ranges of records wherein the index and records are ordered.
This is done by accessing the first file, the index file wherein all other file addresses are stored in. From the address the files linked in the index are accessed.

ex. for records 0001 to 0100 the index key is A, for records 0101 to 0200 the index key is B

Example:


index file
Partially_indexed.png
The image shows how a key links to the record address that links to a block with the desired records

index key
record
A
0001
B
0101
C
0201
D
0301
record file
record
belongs to file
0001...
do.this
...0100
super.help
0101...
cube.make
...0200
cube.move
0201...
cube.rotate
...0300
polygon.make
0301...
polygon.getsnumberofsides()

Created by: Daniel Gillo
Last modification: 5th September 2011

Sources:
  • Jones, Richard. Computer Science Java Enabled. Victoria: IBID Press, 2004