Re: Why use variable length fields?

["R. Bruce Hoffman, Jr." <rbruceh@xxxxxxxxxxxxx>]

What you are missing is that you are looking at the definition, the
capability of the field, not the storage used.

Populate it with 30 character fields, and look at the storage size.

Then clear it, populate it with 100 character fields and look again at the
storage size.

ps. Put in LOTS of records, not just one or two.

===========================================================
R. Bruce Hoffman, Jr.
 -- IBM Certified Specialist - AS/400 Administrator
 -- IBM Certified Specialist - RPG IV Developer

"Those who would give up essential Liberty,
  to purchase a little temporary Safety,
  deserve neither Liberty nor Safety."

     - The Papers of Ben Franklin

-----Original Message-----
From: Joe Giusto <JGiusto@patuxent.com>
To: 'MIDRANGE-L@midrange.com' <MIDRANGE-L@midrange.com>
Date: Monday, July 17, 2000 4:58 PM
Subject: RE: Why use variable length fields?


>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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