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, [email protected] 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 <[email protected]>
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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