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DBMS Physical Design
Physical design is
concerned with the
placement of data and
selection of access
methods for efficiency
and ongoing maintenance

File Organization
Physical arrangement of the records of a file on
secondary storage devices
•Sequential
•Linked List
•Indexed
•Hashed

Sequential File
addr
00 Ayers ACCT
01 Buckley MGT
02 Daley ACCT
03 Dejoie MGT
04 Kenderdine MKT
05 Linn FIN
06 Lusch MKT
07 Price MGT
08 Razook MKT
09 Schwarzkopf MGT
Sequential file sorted in alphabetical order.
Sequential files are usually sorted in ID
sequence order to facilitate batch processing.

Sequential File Processing
Transaction
Old Master
New MasterProcess
Sequential files must be recopied from the point of
any insertion or deletion to the end of the file. They
are commonly used in batch processing where a
new master file will be generated each time the file
is updated.

Linked List
addr pointer
00 Price MGT 01
01 Schwarzkopf MGT 02
02 Kenderdine MKT 03
03 Lusch MKT 08
04 Buckley MGT 09
05 Ayers ACCT 06
06 Daley ACCT 07
07 Linn FIN 04
08 Razook MKT ##
09 Dejoie MGT 00
Linked list to sort data alphabetically within department.
An external reference must point to the start record (05).

Linked List File Processing
The next record in a linked list is found at the address
stored in the record. Records are added at any
location in the DASD and pointers adjusted to include
them. Deletions are not erased, but pointers
changed to omit the deleted record.http://ebooks.edhole.com

Indexed File
(sequential index)
addr
00 Price MGT Ayers ACCT
01 Schwarzkopf MGT Daley ACCT
02 Kenderdine MKT Linn FIN
03 Lusch MKT Razook MKT
04 Buckley MGT Dejoie MGT
ACCT 00
ACCT 01
FIN 02
MGT 00
MGT 01
MGT 04
MKT 03
Index to access data by
department abbreviation.

Indexed File Processing
Index
Data File
When a record is inserted or deleted in a file the data
can be added at any location in the data file. Each index
must also be updated to reflect the change. For a
simple sequential index this may mean rewriting the
index for each insertion.
Index

Segmented Index
addr
00 Price MGT Ayers ACCT
01 Schwarzkopf MGT Daley ACCT
02 Kenderdine MKT Linn FIN
03 Lusch MKT Razook MKT
04 Buckley MGT Dejoie MGT
05 Van Horn MGT
addr pointer pointer pointer
100 101 Kenderdine 102 Razook 103
101 200 Buckley 201 Dejoie 204
102 203 Lusch 202
103 205 Schwarzkopf 206
200 00 Ayers 04 Buckley 201
201 01 Daley 04 Dejoie 204
202 00 Price 03 Razook 205
203 02 Linn 03 Lusch 202
204 02 Kenderdine 203
205 01 Schwarzkopf 206
206 5 Van Horn
Index
Data
Leaf
Root
Nodes

Indexed File Processing
(segmented index)
Data File
Index
Data can be inserted or deleted at any location in the
data file. The index(es) must be updated for each
change, but only the affected segments need to be
rewritten.

Physical Design
Volume and Usage analysis
Distribution Strategy
File Organizations
Indexes and Access Methods
Integrity Constraints

Physical Design Issues
Size
Speed of access
Speed of update
Growth issues: performance and
degradation
Security
Maintenance

DBMS Organization
Relationships: physical
address pointers
Links generated when data is
entered
Efficient but not flexible
Ad hoc design
Query dependent on specific
DBMS (may support SQL)
Relationships: logical data
references
Links generated when data is
retrieved
Flexible but not efficient
Theoretical base
SQL
Structured Relational

DBMS Technology
• CPU
• Components
• Operation
• DASD
• Technology
• Organization
• Data Transfer
• Access methods

Physical Design
Data Distribution
Centralized
Partitioned
Horizontal
Vertical
Replicated
Hybrid

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