What is the difference between Delta and Changed Sampling in SNMP

[hfakoor222]

The section right before where the commands begin

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/snmp/configuration/xe-16/snmp-xe-16-book/nm-snmp-cfg-snmp-support.html

Absolute Sampling

Absolute sampling uses the value of the MIB object during sampling.

Delta Sampling

Delta sampling is used for expressions with counters that are identified based on delta (difference) from one sample to the next. Delta sampling requires the application to do continuous sampling, because it uses the value of the last sample.

Changed Sampling

Changed sampling uses the changed value of the object since the last sample.

It seems to m Delta and Changed sampling are the same thing, by the wayi is described, as a change from the last sample taken. Unless delta sampling stores the changes differently I myself do not see a difference.

Any further insight?

[Georg Pauwen · Accepted solution]

Hello,

interesting question. I looked around and found another explanation (see below). As I understand it, delta means the difference between the current and the previous sample, while changed means changed or not, so it is sampled only when there is a change.

I am not sure if that is correct, but that is my understanding...

The method of sampling the selected variable.
An 'absoluteValue' is simply the present value of the object.
A 'deltaValue' is the present value minus the previous value, which was sampled expExpressionDeltaInterval seconds ago.
This is intended primarily for use with SNMP counters, which are meaningless as an 'absoluteValue', but may be used with any integer-based value.
A 'changedValue' is a boolean for whether the present value is different from the previous value.
It is applicable to any data type and results in an Unsigned32 with value 1 if the object's value is changed and 0 if not.
In all other respects it is as a 'deltaValue' and all statements and operation regarding delta values apply to changed values.
When an expression contains both delta and absolute values the absolute values are obtained at the end of the delta period.

[hfakoor222]

Thank you

In math delta refers to change of x over y or rates of change over time from my understanding