RE: Variable length fields

[Vern Hamberg <vhamberg@xxxxxxxxxxxxxxxxxxxxxxxxx>]

VARLEN(0) will give the best space usage, as everything is packed into the 
auxiliary space. This is reflected in the results given. If most of the 
data is shorter than the allocated length, there will be wasted space. The 
overhead to link the records to the auxiliary space can have a bearing. 
Just as in ZIP files, there are instances where the "compressed" version is 
larger than the original.

The drawback to VARLEN(0) is performance - up to double the I/O to get the 
records. If you are lucky and the auxiliary space has data for multiple 
varlen columns fairly close together, so that the pages are already in 
memory for the next record, it won't be too bad. But it's a crapshoot.

Vern

At 11:40 AM 7/1/2004, you wrote:
> David,
>
> Did you by any chance reverse the figures for cases 1 and 2?  It makes no
> sense that the file is larger for the allocated length case _unless_ a
> substantial number of the fields had content that exceeded the allocated
> length.  Perhaps that was the case in your tests.
>
> As has been noted earlier, VARLEN will only save storage when a substantial
> proportion of the records have content _within_ the allocated length.
>
> Jon Paris
> Partner400
> www.Partner400.com
>
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