Hi Derek, Yesterday Derek Haynes wrote:
> Several times on the list, the topic of a CF SUM function has > risen...just a sample: > > http://oss.oetiker.ch/rrdtool/forum.en.html#nabble-td1059458 > http://oss.oetiker.ch/rrdtool/forum.en.html#nabble-td1059458 > http://oss.oetiker.ch/rrdtool/forum.en.html#nabble-td1059458 > > I'm in need of a similar CF SUM function and I was curious if there > isn't one because (1) there's a fundemental reason why it's not > provided or (2) it just hasn't been implemented. the fundamental problem with a SUM CF is that the values of the RRA entries would then depend on the step interval of the RRA and thus fundamentally change the nature of the RRAs ... > For reason (1), the common argument is you can calculate this by > multiplying the average by the duration of the CDP. However, this > doesn't hold when a CDP contains unknowns as the average is only based > on the known values. basing a sum on unknown values might be problematic too a + unknown = a would mean that you assume that unknown equals 0 where we curently make the assumtion that the unknown part of the periode was similar to the known parts ... in any event, on a technical level, what would be required to achieve what you want (appart for the handling of unknown periodes within a single step) would be an AVERAGE_UNKNOWN_AS_ZERO consolidation function ... this would not break the assumptions about the nature of RRAs and you could calculate your type of SUM easily ... cheers tobi > The TOTAL operator does exactly what I'm looking for but it's only for > VDEF statements. > Any thoughts? > > Derek > > -- Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland http://it.oetiker.ch t...@oetiker.ch ++41 62 775 9902 / sb: -9900 _______________________________________________ rrd-users mailing list rrd-users@lists.oetiker.ch https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users
