Calculated item f:(skewness,30d) = Not supported. When data is.

[Rudlafik]

Hi,
I add to LLD Net intf. new item prototype - calculated item skewness(//net.if.status[ifOperStatus.{#SNMPINDEX}],30d).

Problem:
When the value is constant over the time period examined. ie always 2 or always 1. => The result of the skeewness function is "Not Supported".
Cannot evaluate function: cannot calculate skewness() value at "skewness(//net.if.status[ifOperStatus.237],30d)".

I expected the values not infinity and minus infinity, but at least the returned values something like 1000000 etc.

At the moment, a lot of calculated items on network elements with the value Not Supported are causing me a real problem with "ValueCacheSize" on the Zabbix server.

Do you have a tip or advice to get around this? And make infinity = Not supported item some value that returns a number or how to automatically turn off such an item?
I need it for port statistics on switches and this is kind of annoying stuff.
When the data in Zabbix is, but the function reports Not Supported instead of a reasonable return value.
I understand the given function and its limit to infinity in the case of immutable values, but I need to treat the result. Even infinity is mathematically a result, not Not Supported.

Thanks for your ideas or even escalation as a bug.

[Rudlafik]

Now I try Preprocessing on two tests:

• - Check for not supported value/Discard value
• - In range -1000000 - 1000000/Discard value