Thomas Lockhart wrote:
> ...
> > > > Hard to imagine why anyone would want such an optimization. How much
> > > > faster could it possibly be?
> > > Back in ye bad olde days, there was probably an order-of-magnitude
> > > difference between the speed of a float multiply and that of a float
> > > divide; so this used to be a pretty standard sort of optimization.
> > > I can remember doing the equivalent thing by hand in source code.
> > > On modern hardware I doubt it makes much difference...
>
> The speed difference is still there; you can't do a divide with one pass
> through a barrel shifter, which is how the multiply operations were sped
> up. I vaguely recall something like a 40:1 ratio on a 604 PowerPC but
> that may not be accurate, or may be for integers which have similar
> issues.
Wow, 40:1 is a major difference.
> > And you would have to do a heck of a lot of them to see a difference.
>
> ?? Some applications *do* do a heck of a lot of them ;)
Yep, I am sure. The question is whether there is ever a reason to use
such a flag on the database code. My guess is no.
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
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