[collectd] MySQL plugin reports wrong numbers on mysqld restart

[Bostjan Skufca]

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