RE: Why use variable length fields?

[Joe Giusto <JGiusto@xxxxxxxxxxxx>]

So I set up a test with 2 fields and then do a DSPFFD and here is what I
get:

Number of fields  . . . . . . . . . . . . . :      2

   Record length . . . . . . . . . . . . . . . :    103

 Field Level Information

              Data        Field  Buffer    Buffer        Field    Column

   Field      Type       Length  Length  Position        Usage    Heading

   FLD1       CHAR          100     102         1        Both     FLD1

     Variable length field -- Allocated length :     30

     Coded Character Set Identifier  . . . . . :     37

   FLD2       CHAR            1       1       103        Both     FLD2

     Coded Character Set Identifier  . . . . . :     37

 
Bottom

It looks to me like it is actually taking up more space than if I just left
FLD1 at 100 without the varlen.
What am I missing?


-----Original Message-----
From:   Westdorp, Tom [SMTP:tom.westdorp@stationcasinos.com]
Sent:   Monday, July 17, 2000 2:52 PM
To:     MIDRANGE-L@midrange.com
Subject:        RE: Why use variable length fields?

They don't have to be defined at their maximum length you define the
allocated length and the maximum length for example:
----------------- The following copied from OS/400 DDS Reference v4r4
-----------     

Use this field-level keyword to define this field as a variable-length
field. Variable-length fields are useful for improving storage when the data
for the field typically fits within a certain length, but can occasionally
be longer. Specify the maximum length of the field in positions 30 to 34.
You can specify the allocated length (or typical length) in the parameter.

FIELD1       100A         VARLEN(30)

The allocated-length parameter is optional. Use it to specify the number of
bytes allocated for the field in the fixed portion of the file. If you do
not specify the allocated-length parameter, the data for this field is
stored in the variable length portion of the file.
 
Valid values for the allocated-length parameter are 1 to the maximum length
of the field specified in positions 30 to 34.

The VARLEN keyword is valid only on character fields.
 
When you specify the VARLEN keyword, the maximum length you can specify in
positions 30 to 34 is 32 740 (32 739 if the field allows the null value).
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