Be interested in whether Chuck or anyone else know differently Alan -
but my understanding has always been that the overflow is only
accessed as and when needed.
On 2014-07-29, at 12:16 PM, Alan Campin wrote:
Based on what has been said on the forum before,
1. Whenever you display anything from the database, the database
will always present it as if there was one field. The sticking
together occurs at the lowest level of the DB.
2. According to what I know, it does not matter. IBM always go to
the overflow and reads it in no matter what so I am not sure the
VARLEN does you any good. I guess the only thing it would do for
you is reduce the amount of disk storage required.
On Tue, Jul 29, 2014 at 10:09 AM, John R. Smith, Jr. wrote:
I have some questions about variable length fields in files
created using DDS.
When I learned about them, I was told that if there is a field
with a max of 100 bytes with a VARLEN(20), the system allocates
20 bytes in the record and if the value is longer than 20 bytes,
it stores the additionally needed bytes elsewhere. When the
record is read, the OS knows to retrieve the 20 bytes from the
record and concatenates the additional bytes from the elsewhere
storage (if any exist) and it returns a 100 byte field. The net
result is less DASD tied up with extraneous spaces in the file
with no impact to the developer. However, when I look at the
file via DSPPFM or WRKLNK, I see all 100 bytes even if all 100
My questions are:
1) Is the OS smart enough to pad out the 21-100 bytes when
displayed via WRKLNK and DSPPFM so I don't see the difference or
is my understanding of how the DDS VARLEN works flawed?
2) Assuming my VARLEN is guessed correctly and most records fit
into the allocated bytes, is there any noticeable impact with
using VARLEN fields?
3) If my guess is incorrect and a big chunk of records require
the additional 21-100 bytes, does this have a huge performance
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