On 06/01/2018 12:25 PM, Guyren Howe wrote:
On Jun 1, 2018, at 10:16 , Olivier Gautherot <olivier@xxxxxxxxxxxxx> wrote:
You will get a benefit in terms of
space only if the optional fields in the second table
exist in a reduced number of instances - and the second
table is significantly wider. This can make a difference
on big tables but this gain may be offset by the cost of
the join. In this perspective, I don’t think that there is
a clear benefit or drawback: it should be evaluated on a
case-by-case basis.
It seems to me that people take time to catch up with
modern hardware reality. SSDs reduce seek time to virtually
zero. Surely, joins are now much, much cheaper. If so, I’m
inclined to describe wide tables as a premature optimization.
Sure, SSDs are uber-wonderful, but a rack full of rotating media is
still going to be a lot cheaper and have a lot more capacity than a
rack full of SSDs, and that makes all the difference...
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