Methods for Processing Disk Files

Edit online

The methods of disk file processing include:

  • Consecutive processing
  • Sequential-by-key processing
  • Random-by-key processing
  • Sequential-within-limits processing.
  • Relative-record-number processing

Table 1 shows the valid entries for positions 28, 34, and 35 of the file description specification for the various file types and processing methods. The subsequent text describes each method of processing.

Table 1. Processing Methods for DISK Files
Processing Method
Limits
Processing
(Pos. 28)
Record
Address
Type
(Pos. 34)
File
Organization
(Pos. 35)
Externally Described Files
 
With Keys
 
   Sequentially
   Randomly
   Sequential within limits
    (by record-address file)
 
Without Keys
 
   Randomly/consecutively
 
 
 
 
 
Blank
Blank
L
 
 
 
 
Blank
 
 
 
 
 
K
K
K
 
 
 
 
Blank
 
 
 
 
 
Blank
Blank
Blank
 
 
 
 
Blank
 
Program Described Files
 
With Keys (indexed file)
 
   Sequentially
 
   Randomly
 
   Sequential within limits
     (by record-address file)
 
Without Keys
 
   Randomly/consecutively
   By record-address file
   As record-address file
     (relative record numbers)
   As record-address limits file
 
 
 
 
 
 
Blank
 
Blank
 
L
 
 
 
 
Blank
Blank
Blank
 
Blank
 
 
 
 
 
 
A, D, G, P,
T, Z, or F
A, D, G, P,
  T, Z, or F
A, D, G, P,
  T, Z, or F
 
 
 
Blank
Blank
Blank
 
A, D, G, P,
T, Z, F, or
Blank
 
 
 
 
 
I
 
I
 
I
 
 
 
 
Blank
Blank
T
 
Blank