Database Reference
In-Depth Information
50
Number of attributes = 3
Number of tuples = million
45
40
35
30
25
20
15
10
5
0
2
3
4
Number of Classification Levels
5
6
SeaView
MLR
Jajodia-Sandhu
Belief-Consistent
Smith-Winslett
MLS-Encryption
Figure 5.13 Impact of varying the number of security levels in a join query. (L. Pan. 2008.
Proceedings of International Symposium on Electronic Commerce and Security, 518-522.)
From FigureĀ 5.13 the response times grow for all models as the number
of the security levels is increased. Also, supporting encryption in the
encryption-based multilevel database model improves the performance
of a multilevel database because the database size is decreased due to
removing the extra attributes used for the class levels.
5.4.4 UPDATE Query
The number of the updated tuples is varied from 100,000 to 500,000,
750,000, and 1,000,000. Fix the number of attributes at three; fix the
number of security levels at four. From FigureĀ 5.14 the response times
grow for all models as the number of tuples is increased. Also, sup-
porting encryption in the encryption-based multilevel database model
decreases the performance of a multilevel database because, during
the execution of the update statement, the encryption and decryption
mechanisms will be included together in the update procedure.
The where clause in the UPDATE query will be taken into consid-
eration when we evaluate the performance of the multilevel database
 
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