On Thu, Dec 31, 2015 at 12:48 PM, Tomas Vondra <tomas.von...@2ndquadrant.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 -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
