Re: Why use variable length fields?

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

-----Original Message-----
From: Joe Giusto <JGiusto@patuxent.com>
To: 'midrange-l@midrange.com' <midrange-l@midrange.com>
Date: Monday, July 17, 2000 2:50 PM
Subject: Why use variable length fields?


>I have seen some posts about variable length fields.  If they have to be
>defined at their maximum length anyway, what is the advantage to using
them.
>Dose it really save space on the system?
>


For small field no, there is some overhead (12 additional bytes I think) but
for large fields that are generally not fully populated, then yes.

For example, you need a max length of 512 bytes, but the average data stored
is 50 bytes.  Say there are 8 million records and only 17 records have 510
bytes of data.

That would be 496 million bytes (counting overhead) of data used instead of
a fixed field of 512 and 4,096 million bytes.

===========================================================
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



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