Greg Stark <[email protected]> writes:
> On Sat, Nov 20, 2010 at 6:31 PM, Tom Lane <[email protected]> wrote:
>> Robert Haas <[email protected]> writes:
>>> I had given some thought to whether it might make sense to try to
>>> figure out how long the string will be before we actually start
>>> generating it, so that we can just start in the exactly right space
>>> and have to clean up afterward. But the obvious implementation seems
>>> like it could be more expensive than just doing the copy.
>> Yeah. You certainly don't want to do the division sequence twice,
>> and a log() call wouldn't be cheap either, and there don't seem to
>> be many other alternatives.
> There are bittwiddling hacks for computing log based 2. I'm not sure
> it's worth worrying about to this degree though.
I think converting log2 to log10 *exactly* would end up being not so
cheap, anyhow.
regards, tom lane
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