[rrd-users] Newby questions

[Pablo Chacin]

I think that "it is not a database" is not the point.

The point is: is the way unknown values handle
coherent with the calculation of totals?

As I see it, there's no fundamental reason not to
be able to calculate totals in a RRD. Other implementations
of the concept, as StatsD and Graphite allows it.



On 10/30/2012 03:51 AM, j.halifax2 at seznam.cz wrote:
>
>
> >I realize RRD is not an ANSI SQL compliant database
>
>
> Correct. Even the rrd isn't a database at all.
>
>
> jh
>
>

> ---------- Původní zpráva ----------
> Od: Pablo Sanchez <pablo at blueoakdb.com>
> Datum: 30. 10. 2012
> Předmět: Re: [rrd-users] Newby questions
>
>     [ Comments below, in-line ]
>
>     On 10/29/2012 06:57 PM, Tobias Oetiker wrote:
>     > Today Pablo Chacin wrote:
>     >
>     >> For example:
>     >>
>     >>> 0:UNKN 300:10 600:10 900:10
>     >>>
>     >>> consolidated and then mulitplied by the period will produce the
>     >>> same value as if all entries were 10, and not with one UNKN (given
>     >>> the cf is 0.5). A SUM function would nicely return 30.
>     >>>
>     >
>     > otoh, why would you want to count UNKNOWN as ZERO ? isn't more
>     > corect to asume that the values during the time where you have no
>     > information were the same as in over the rest of the interval ?
>
>     Hey Tobi,
>
>     I realize RRD is not an ANSI SQL compliant database (*grin*) ... some
>     confusion might arise that in a database, NULL (unknown) is not
>     sum()'d:
>
>     --8-<---8-<---8-<---8-<---8-<---8-<---8-<--
>     19:05:23 plugh > insert into tobi values (1);
>
>     1 row created.
>
>     Elapsed: 00:00:00.00
>     19:05:31 plugh > insert into tobi values (4);
>
>     1 row created.
>
>     Elapsed: 00:00:00.01
>     19:05:36 plugh > insert into tobi values (8);
>
>     1 row created.
>
>     Elapsed: 00:00:00.00
>     19:05:38 plugh > insert into tobi values (null);
>
>     1 row created.
>
>     Elapsed: 00:00:00.00
>     19:05:44 plugh > commit;
>
>     Commit complete.
>
>     Elapsed: 00:00:00.10
>     19:05:46 plugh > select * from tobi;
>
>     SOME_COLUMN
>     -----------
>     1
>     4
>     8
>
>
>     Elapsed: 00:00:00.01
>     19:05:49 plugh > select sum(some_column) from tobi;
>
>     SUM(SOME_COLUMN)
>     ----------------
>     13
>
>     Elapsed: 00:00:00.00
>     19:05:58 plugh >
>     -- 
>     Pablo Sanchez - Blueoak Database Engineering, Inc
>     Ph: 819.459.1926 Blog: http://pablo.blog.blueoakdb.com
>     Fax: 760.860.5225 (US)
>
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-- 
Pablo Chacin
R&D Engineer
SenseFields SL
Tlf (+34) 93 418 05 85
Baixada de Gomis 1,
08023 Barcelona (Spain)
http://www.sensefields.com/


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