If you group by label, and the label is missing or empty (which are the
same thing in prometheus), you get no results. e.g.
sum by (foo) (node_filesystem_avail_bytes)
I think what you have to do is to use label_replace to synthesize a dummy
value for the missing label:
sum by (foo)
(label_replace(node_filesystem_avail_bytes,"foo","unset","foo",""))
This converts
mymetric{bar="baz"}
into
mymetric{bar="baz",foo="unset"}
On Saturday, 17 June 2023 at 16:20:23 UTC Moksha Reddy G wrote:
> Hi Brian,
>
> Thanks for your response.
> Now I am clear about my case1, but still I have questions on case2 and
> case3. I prefer to go one by one, please find my question below on Case2:
>
> *Case2: *Below queries are responding with results but it is giving *Empty
> query results *when I choose the date/time before I introduced
> *clusterName* as a label. Label value should be common as* $clustername *in
> both label keys.
> sum(kube_pod_info{k8s_cluster=~"dd-stg*|*", clusterName=~"dd-stg*|*"}) by
> (clusterName, k8s_cluster)
> sum(irate(pilot_xds_pushes{type=~"rds", clusterName=~"dd-stg|",
> k8s_cluster=~"dd-stg|"}[5m])) by (clusterName, k8s_cluster)
> *For example:* If I choose a 1 month old timeline(*2023-05-01*) when
> there is no label called *clusterName *then NO results displayed*. *If I
> choose the current timeframe then it works. *clusterName* label has been
> introduced recently one month back, It is because of the availability of
> the label at that point in time. *BUT we need old data also with both(*
> clusterName, k8s_cluster*) labels so what is the correct way of defining
> the query in such cases?*
> [image: image.png]
> [image: image.png]
> [image: image.png]
>
> Best,
> Reddy
>
>
>
> On Sat, Jun 17, 2023 at 3:28 AM Brian Candler <[email protected]> wrote:
>
>> In your case 1,
>> *clusterName=" $clustername|"*
>> should be
>> *clusterName=~" $clustername|"*
>> Your screenshot shows this mistake as well.
>>
>> You stated "Below query is not at all working as it contains other
>> condition in beginning." I think you need to clarify both parts of that
>> statement:
>>
>> (1) in what way is it not working? Show the input metrics, the result of
>> the query, and what result you're actually looking for.
>>
>> If the problem is that it returns an empty result set (as per your
>> screenshot), that's because you used the wrong label match operator, "="
>> instead of "=~". It will only match a clusterName which has the exact
>> literal value "d3-prd-w2|" (including the vertical bar).
>>
>> (2) "as it contains other condition in beginning" doesn't mean anything
>> to me. What conditions? Do you mean the label filter type="cds"?
>> Then clearly it will only match metrics that have that label. Is that not
>> what you want?
>>
>> In your case 3, I think you have another bug:
>> (kube_pod_info{k8s_cluster=~"$clustername"} or {clusterName=~"$
>> clustername"})
>> should be
>> (kube_pod_info{k8s_cluster=~"$clustername"} or kube_pod_info
>> {clusterName=~"$clustername"})
>>
>> > OR is not working in all cases due to binary expressions in queries
>>
>> That doesn't mean anything. The semantics of the OR operator are clearly
>> defined. Show examples of what metrics you are feeding into this query,
>> what you get as the output, and what you would *like* to see instead, and
>> we may be able to help you formulate a query that does what you want.
>>
>> In other words, the problem is not that "OR is not working" - the problem
>> is that you haven't formulated your PromQL query in a way which gets you
>> the results you're looking for.
>>
>> > Could you please look into this issue on high priority
>>
>> I refer you to http://www.catb.org/~esr/faqs/smart-questions.html#urgent
>> (however, the whole of that document is well worth reading)
>>
>> On Saturday, 17 June 2023 at 02:39:50 UTC Moksha Reddy G wrote:
>>
>>> Hey there,
>>>
>>> I am struggling to find simple and efficient OR logic operator for my
>>> Prometheus queries which are running through Grafana dashboards.
>>>
>>> *Problem Statement: *
>>> *Case1*: Below query is not at all working as it contains other
>>> condition in beginning. We have many queries like that and need the correct
>>> syntax to use logic OR condition. Label value should be common as
>>> * $clustername *in both label keys
>>> sum(irate(pilot_xds_pushes{type="cds",*clusterName=" $clustername|",
>>> k8s_cluster=" $clustername|"*}[5m]))
>>>
>>> *Case2*: Below query is responding with results but it is giving *Empty
>>> query result *when I choose the date/time before I introduced
>>> *clusterName* as a label. Label value should be common as
>>> * $clustername *in both label keys.
>>> sum(kube_pod_info{k8s_cluster=~"$clustername*|*",
>>> clusterName=~"$clustername*|*"}) by (clusterName, k8s_cluster)
>>> *For example:* If I choose 1 month old timeframe when there is no label
>>> called *clusterName *then NO results displayed*. *If I choose current
>>> timeframe then it works. I guess it is because the availability of the
>>> label in Prometheus database. What is the logic from Prometheus backend?
>>>
>>> *Case3**: *If I put *OR* operator in between these two conditions then
>>> its working but OR is not working in all cases due to binary expressions in
>>> queries. Below is the query:
>>> sum(kube_pod_info{k8s_cluster=~"$clustername"} or {clusterName=~"$
>>> clustername"}) by (clusterName, k8s_cluster)
>>>
>>> Could you please look into this issue on high priority and kindly share
>>> your inputs to use this OR operator without any issues in all these
>>> scenarios?
>>>
>>> Best,
>>> Reddy
>>>
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