Re: PATCH: Extending the HyperLogLog API a bit

On Thu, Dec 31, 2015 at 12:48 PM, Tomas Vondra
<tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
> 1) initHyperLogLogError(hyperLogLogState *cState, double error)
>
> Instead of specifying bwidth (essentially the number of bits used
> for addressing in the counter), this allows specifying the expected
> error rate for the counter, which is
>
> error_rate = 1.04 / sqrt(2^bwidth)
>
> So for 5% we get bwidth=5, and so on. This makes the API a bit easier
> the use, because there are pretty much no comments about the meaning
> of bwidth, and the existing callers simply use 10 without details.

Fair, but you didn't add any better comments!

> 2) freeHyperLogLog(hyperLogLogState *cState)
>
> I think it's a good idea to provide function "undoing" what init
> does, i.e. freeing the internal memory etc. Currently that's trivial
> to do, but perhaps we'll make the structure more complicated in the
> future (albeit that might be unlikely).

Seems reasonable.

--
Peter Geoghegan