[collectd] MySQL plugin reports wrong numbers on mysqld restart

Bostjan Skufca bostjan at a2o.si
Thu Sep 30 03:02:06 CEST 2010

This COUNTER->DERIVE does the trick. Transition script complete,
thanks for all your help.


On 29 September 2010 20:15, Bostjan Skufca <bostjan at a2o.si> wrote:
> Hey, by my calculations in six hours I should receive a reply with
> even easier solution to all issues mentioned and maybe some other ones
> too. :)
> Serious business below. :)
> On 29 September 2010 17:56, Florian Forster <octo at collectd.org> wrote:
>> Hi Bostjan, Mariusz and everybody else ;)
>> On Wed, Sep 29, 2010 at 02:47:08PM +0200, XANi wrote:
>>> Dnia 2010-09-29, śro o godzinie 03:09 +0200, Bostjan Skufca pisze:
>>> > Maybe it's time to make a script for automated dump/change obviously
>>> > invalid data to NaN/import of rrds.
>> What's obvious to you is not obvious for a script. So I'm afraid you'll
>> be stuck with some manual tuning or write a script specifically suited
>> for your needs.
> Probably, but I'll have to do it anyway to fix the spikes.
>>> > Do you know how  why it was not DERIVE specified at rrd creation?
>>> Datatype was not DERIVE probably because mysql plugin (as many other)
>>> is much older than actual DERIVE support in collectd :)
>> 100% right: Support for DERIVE was added relatively late – much later
>> than the MySQL plugin. The next major version, version 5.0, will likely
>> convert most of the COUNTER data sources to DERIVE – it's the better
>> default in most cases.
> Can you think of any example where it would be bad/improper to convert?
>>> > Probably I should consult google and manuals for this, but: is there
>>> > an easy way to change from COUNTER to DERIVE or do I have to dump
>>> > and reload the data?
>>> As for changing counter to derive, simple rrdtool dump to xml file and
>>> find/replace should be enougth
>> That's too complicated. You can use "rrdtool tune" (rrdtune(1)) to do
>> this without much hassle:
>>  rrdtool tune mysql_commands-select.rrd --data-source-type value:DERIVE
> From The Incredibles: "That's the way they do it!" Thanks for the hint!
> Best regards,
> b.

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