IBM AS/400 manual Using, Pre-V3R1 DDM

DDM

Files

The DDM file provides the

information

needed

for a local system to

system

and

to

access

the

data in the source file. For more informa

DDM

and

creating

DDM

files,

referDistributedto the Data

Managemeanualt .

Using

Pre-V3R1 DDM

Files

If

you

are

using

a

pre-Version

3

Release

1.0 DDM file, the key

done

at

the

Data

Management

level during

a

READE

or

READPE

operation,

indicator

for

SETLL,

or during sequential-within-limits processing

by a

r

address

file.

The

READE or READPE operation, EQ indicator for SETLL, or

sequential-within-limits

processing by a record address file, will inst

keys

using

the

*HEX

collating

sequence.

This may give different results than expected

when

DDS features

are

cause

more

than

one

search

argument

to

match

a given key in the

fi

example,

if

ABSVAL

is

used

on

a

numeric

key,

both

-1 and

1

would

su

search

arguments

for

a key

in the file with a value of 1. Using

collating

sequence,

a

search argument of -1

will

not

succeed

for

an

Some

of

the

DDS

features that

cause the key

comparison

to

differ

¹

ALTSEQ

specified

for

the

file

¹ ABSVAL, ZONE, UNSIGNED, or DIGIT keywords on key fields

¹ Variable length, Date, Time, or Timestamp key fields

¹ The SRTSEQ for the file is not *HEX

¹ALWNULL(*USRCTL) was specified on the creation command and a key in record or the search argument has a null value (this applies only described files)

In

addition,

if

the

sign

of

a

numeric

field

is

different

from

the

the

key comparison will also differ.

The

first

time

that

the

key

comparison

is not

done

at

the

Data

Mana

a

pre-V3R1

DDM

file during the READE or READPE

operation,

EQ

indicator

SETLL, or

during

sequential-within-limits processing

by

a

record

address

informational

message

(RNI2002)

will

be issued.

Note: The performance of I/O operations that have the possibility of record (SETLL, CHAIN, SETGT, READE, READPE), will be slower than the pre-Version 3 Release 1.0 equivalent.

Chapter 16. Accessing Database 313Files