[jira] [Updated] (FLINK-7781) Support simple on-demand metrics aggregation

["Chesnay Schepler (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-7781?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Chesnay Schepler updated FLINK-7781:
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    Summary: Support simple on-demand metrics aggregation  (was: Support sime on-demand metrics aggregation)

> Support simple on-demand metrics aggregation
> --------------------------------------------
>
>                 Key: FLINK-7781
>                 URL: https://issues.apache.org/jira/browse/FLINK-7781
>             Project: Flink
>          Issue Type: Improvement
>          Components: Metrics, REST
>    Affects Versions: 1.4.0
>            Reporter: Chesnay Schepler
>             Fix For: 1.4.0
>
>
> We should support aggregations (min, max, avg, sum) of metrics in the REST API. This is primarily about aggregating across subtasks, for example the number of incoming records across all subtasks.
> This is useful for simple use-cases where a dedicated metrics backend is overkill, and will allow us to provide better metrics in the web UI (since we can expose these aggregated as well).
> I propose to add a new query parameter "agg=[min,max,avg,sum]". As a start this parameter should only be used for task metrics. (This is simply the main use-case i have in mind)
> The aggregation should (naturally) only work for numeric metrics.
> We will need a HashSet of metrics that exist for subtasks of a given tasks that has to be updated in {{MetricStore#add}}.
> All task metrics are either stored as
> # {{<subtask-index>.<metric>}} or
> # {{<subtask-index>.<operator-name>.<metric>}}.
> If a user sends a request {{get=mymetric,agg=sum}}, only the metrics of the first kind are to be considered. Similarly, given a request {{get=myoperator.mymetric,agg=sum}} only metrics of the second kind are to be considered.
> Ideally, the name of the aggregated metric (i.e. the original name without subtask index) is also contained in the list of available metrics.



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