Vrushali C commented on YARN-3901:
The application and entity tables support timeseries storage.
For flow runs, having a timeseries means having to normalize the time
granularity for the timeseries. For example, say a flow has 3 apps. Say all 3
apps run more or less concurrently. App1 has a metric1 value at ts1 but app2
will have the metric1 at ts2 and say app3 has metric1 value at ts3, now for the
metric at flow run level, what should be the values at ts1, ts2 and ts3? So we
would need to "normalize" it across say per minute or per hour or something.
There was another discussion on this, do you recollect the jira [~gtCarrera9] ?
The end values can be aggregated since it's the final value, so we can say for
this flow run for this metric, here the value (which would just a sum of that
metric's final values from individual apps).
> Populate flow run data in the flow_run table
> Key: YARN-3901
> URL: https://issues.apache.org/jira/browse/YARN-3901
> Project: Hadoop YARN
> Issue Type: Sub-task
> Components: timelineserver
> Reporter: Vrushali C
> Assignee: Vrushali C
> As per the schema proposed in YARN-3815 in
> filing jira to track creation and population of data in the flow run table.
> Some points that are being considered:
> - Stores per flow run information aggregated across applications, flow version
> RM’s collector writes to on app creation and app completion
> - Per App collector writes to it for metric updates at a slower frequency
> than the metric updates to application table
> primary key: cluster ! user ! flow ! flow run id
> - Only the latest version of flow-level aggregated metrics will be kept, even
> if the entity and application level keep a timeseries.
> - The running_apps column will be incremented on app creation, and
> decremented on app completion.
> - For min_start_time the RM writer will simply write a value with the tag for
> the applicationId. A coprocessor will return the min value of all written
> values. -
> - Upon flush and compactions, the min value between all the cells of this
> column will be written to the cell without any tag (empty tag) and all the
> other cells will be discarded.
> - Ditto for the max_end_time, but then the max will be kept.
> - Tags are represented as #type:value. The type can be not set (0), or can
> indicate running (1) or complete (2). In those cases (for metrics) only
> complete app metrics are collapsed on compaction.
> - The m! values are aggregated (summed) upon read. Only when applications are
> completed (indicated by tag type 2) can the values be collapsed.
> - The application ids that have completed and been aggregated into the flow
> numbers are retained in a separate column for historical tracking: we don’t
> want to re-aggregate for those upon replay
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