Chapter Physical Database Design Methodology Software & Hardware Mapping Logical Design to DBMS Physical Implementation Security Implementation Monitoring and Tuning DBMS

Software & Hardware Define user’s requirement Select software based on user’s requirement Select hardware based on software requirement

Mapping Logical Design to DBMS Create base relations –Name of relation –Attributes (domain & defaults) –Primary key (not null) –Foreign key (referential integrity) –Alternative keys –Indexes Integrity rules –Enterprise –Referential –Entity

Physical Implementation Efficiency measurement –Throughput –Response time Factors for efficiency measurement –Main memory –CPU –Disk I/O (os, database, index, recovery log) –Network (traffic, collisions) –File organization & access method

Physical Implementation Analysis transactions Choose file organizations Add secondary indexes Balance flexibility and performance Estimate disk space

Analyze Transactions Frequency of the transaction - logical access map –max –avg –min Access structure - attributes used in “where” conditions –Relational operations (join, select, project) –Data operations (I, D, U, R) User response time requirement –Day –Time

File Organization Selection Criteria Heap –Bulk-loading –A few pages –Retrieve most record –Primary & secondary indexes Indexed sequential –Exact key match –Direct & sequential accesses –Update deterioration

File Organization Selection Criteria Direct (hash or random) –Direct access –Primary and secondary indexes –Update deterioration –Not for pattern match or range of values B+ tree –Similar to indexed sequential –No overflow problem (deterioration) –Pattern match or range of values –Dynamic growth

Secondary Indexes Overhead consideration –Spaces –Update –Query performance Selection criteria –Do Primary key Heavily used attributes or foreign keys –Don’t Small relations Frequently updated relations Long character strings Retrieve most records

Balance Flexibility and Performance Denormalization –Low update rate –High query rate –Cross-referencing transactions and relations table Steps –Derived data –Redundancy

Derived Data Storage costs Calculation costs Response time

Redundancy - Reduce Join Combining one-to-one relationship (company, store) Duplicating nonkey attributes or foreign keys in one-to-many relationship (po, supplier) Duplicating attributes in man-to-many relationship (student, class) Introducing repeating group –Static –Maximum no. –less than 12

Redundancy - Reduce Join Reference table (type, description) Creating extract tables or relations –Multi-relations (static data and not current or accurate) –Large amount of derived data

Estimate Disk Space Software (DBMS) Hardware (disk spaces) Record size Relation size Storage area for indexes System overhead File organization

Security Implementation User views Access rules –Authorization –Privileges

Monitoring and Tuning DBMS Correct inappropriate design Implement new minor requirement Produce better Response time and throughput Increase user’s satisfaction

Assignment Review chapter 5-6, 11-17, Read chapter 18 Project (enhanced e-r & normalization) –Due date: Project (SQL part) –Due date: