Thanks for the feedback, Prashant

As far as I can tell, we could use the Iceberg Metrics Reporting for only 3
operational metrics:
* Total number of files in a table (using the CommitReport)
* Total number of reads (the number of ScanReport)
* Total number of writes (the number of CommitReport)

I don't think the other operational metrics could be computed from the
Iceberg Metrics.  So we would still need to rely on the Events API.  And I
am wondering whether we should really have two triggers to compute metrics,
considering that with the Events API, we would be able to cover all
documented cases.

That being said, I suspect that there could be other operational metrics
that are missing from the design document.  Typically metrics that would
require the use of the Iceberg Metrics Reporting.  Problem: I cannot find
anything in the community Slack about people requesting Polaris to support
Iceberg Metrics, since we are on the Free plan.  Do you happen to remember
what was discussed?

--

Pierre


On Thu, Sep 4, 2025 at 6:27 PM Prashant Singh
<[email protected]> wrote:

> Thank you for the proposal Pierre !
> I think having metrics on the entities that Polaris is really helpful for
> telemetry as well making decisions on when and what partitions to run
> compactions.
> Iceberg already emits the metric from client end to the rest server
> via RestMetricsReporter
> <
> https://github.com/apache/iceberg/blob/main/core/src/main/java/org/apache/iceberg/rest/RESTMetricsReporter.java#L60
> >
> and
> things like ScanMetrics
> <
> https://github.com/apache/iceberg/blob/main/core/src/main/java/org/apache/iceberg/metrics/ScanMetrics.java
> >
> /
> CommitMetrics
> <
> https://github.com/apache/iceberg/blob/main/core/src/main/java/org/apache/iceberg/metrics/CommitMetrics.java
> >
> are already available but at this point we don't persist them and hence
> they are lost, there has been a request for this in Polaris slack too !
> My recommendations would start from here !
>
> Best,
> Prashant Singh
>
> On Thu, Sep 4, 2025 at 8:41 AM Pierre Laporte <[email protected]>
> wrote:
>
> > Hi folks,
> >
> > I would like to propose the addition of a component to Polaris that would
> > build and maintain operational metrics for the Data Lake tables and
> views.
> > The main idea is that, if those metrics can be shared across multiple
> Table
> > Management Services and/or other external services, then it would make
> > sense to have those metrics served by Polaris.
> >
> > I believe this feature would nor only add value to Polaris but also
> further
> > advance it as central point in the Data Lake.
> >
> > The detailed proposal document is here:
> >
> >
> https://docs.google.com/document/d/1yHvLwqNVD3Z84KYcc_m3c4M8bMijTXg9iP1CR0JXxCc
> >
> > Please let me know if you have any feedback or comment !
> >
> > Thanks
> > --
> >
> > Pierre
> >
>

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