IBM AS/400 manual Using Program-Described Disk Files, Indexed File, Arguments

Using Program-Described Disk Files

no record blocking is done by the compiler, nor by data management. I keyword BLOCK is not specified, then default blocking occurs as descri

The input/output and device-specific					feedback		of the	file	information
are	not	updated	after each	read	or	write	(except	for	the RRN	and
on block		reads)	for files in	which	the records are blocked and unbloc
RPG compiler. The feedback area is					updated each time a block of re
ferred. (For further details on the						file informationILE		dataRPG	forstructure	s
AS/400	Reference.)

You can obtain valid updated feedback information by preventing the fi blocked and unblocked. Use one of the following ways to prevent blocki

¹ Specify BLOCK(*NO) on the file description specification.

¹At run time, use the CL command OVRDBF (Override with Database File) SEQONLY(*NO) specified.

Using Program-Described Disk Files

Program-described files, which are identified by an F in position 22 description specifications, can be described as indexed files, as se as record-address files.

Indexed File

An indexed file is a program-described DISK file whose access path i values. You must create the access path for an indexed file by usi description specifications.

An indexed file is identified by an			I	in	position	35 of	the	file	d
tions.
The	key fields identify	the records	in	an	indexed	file.	You	specif
key	field in positions 29	through 33,	the		format of	the	key	field	i

the starting location of the key field in the KEYLOC keyword of the f specifications.

An indexed file can be processed sequentially by key, sequentially wi randomly by key.

Valid

Search

Arguments

For

a program-described file,

a search

argument

must be a single fiel

CHAIN

and

DELETE

operations,

the

search

argument must be the same length

the

key

field that is defined on the

file

description

specifications

For

the

other file operations, the search argument may be a partial

The

DDS

specifies the fields to be

used

as

a

key

field.

The

KEYLOC

the

file description specifications specify the

starting

position

of t

The

entry in positions 29 through 33

of

the

file

description

specific

specify

the length of the key as defined

in the

DDS.

Figure 141 on

page 289 and

Figure 142

on

page 289

show

examples

of

how

use

the

DDS

to describe

the

access

path

for

indexed

files.

288 ILE RPG for AS/400 Programmer's Guide