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From "Paul Davis" <paul.joseph.da...@gmail.com>
Subject Re: slow views
Date Sun, 21 Dec 2008 12:18:49 GMT
On Sun, Dec 21, 2008 at 1:20 AM, Antony Blakey <antony.blakey@gmail.com> wrote:
>
> On 21/12/2008, at 3:25 PM, Paul Davis wrote:
>
>> Hmm. I don't think so. Technically we could change the implementation
>> to feed reduce functions a single map-row at a time which would be
>> O(N). Might end up violating some (incorrect) expectations of reduce
>> input, but I'm pretty certain it shows that it's O(N).
>
> But you have to combine it with previously reduced input, which means
> fetching a number of previous results, with a cost that isn't clearly
> related to N. Isn't the number of reductions needed to be combined is going
> to be related to key distribution?
>

Good point. I just woke up so the brain is working kinda slow, but are
we describing best case and worst case scenarios too? If each key had
exactly one row and it was group=true, then it'd be O(N). If it was
group=false and every key was identical it'd be log(N). And then
normal use cases are somewhere in the middle?

> Antony Blakey
> -------------
> CTO, Linkuistics Pty Ltd
> Ph: 0438 840 787
>
> It is no measure of health to be well adjusted to a profoundly sick society.
>  -- Jiddu Krishnamurti
>
>
>

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