5.3.8 Minimizing Database I/Os
Initial Example
First Improved Example
Second Improved Example
Files Involved
Physical file TRANS (transactions file) has the following fields:
|
Field
|
Type
|
Length
|
Description
|
|
TRANNUM
|
S
|
5
|
Transaction number
|
|
TRANTIME
|
S
|
6
|
Transaction time
|
|
TRANDATE
|
S
|
6
|
Transaction date
|
|
TRANTYPE
|
A
|
2
|
Transaction type
|
|
TRANUSER
|
A
|
10
|
Transaction user
|
|
TRANSTATE
|
A
|
3
|
Transaction state
|
|
and a file called TRNTYP (transaction types/descriptions) has the following fields:
|
Field
|
Type
|
Length
|
Description
|
|
TRANTYPE
|
A
|
2
|
Transaction type
|
|
TRANDESC
|
A
|
20
|
Transaction full description
|
|
and a file called STATES (state codes/descriptions) has the following fields:
|
Field
|
Type
|
Length
|
Description
|
|
STATCODE
|
A
|
3
|
State code
|
|
STATDESC
|
A
|
20
|
State full description
|
|
Ý 5.3 Sample RDML Programs