Hi Bill,

Sounds good, I'll keep the metric name as is.

Thanks,
Evan

On Wed, Jan 14, 2026 at 3:08 PM Bill Bejeck <[email protected]> wrote:

> Thanks for the KIP Evan, this fills a gap in the metrics for state stores.
>
> With the naming, I agree with Matthias that we probably don't need to do
> anything specific and as it stands is good enough.
> I also think it should be available for all in-memory store types.
>
> Other than that, the KIP lgtm.
>
> Thanks,
> Bill
>
>
>
> On Mon, Jan 12, 2026 at 7:12 PM Matthias J. Sax <[email protected]> wrote:
>
> > Thanks for the KIP Evan.
> >
> > MJS1: Why is the metric added at DEBUG level? The corresponding RocksDB
> > metric is added at INFO level. The KIP says:
> >
> > > The addition of this metric will have no effect on existing users. The
> > performance impact of adding this metric is non-trivial, thus we only
> > record it at the DEBUG level.
> >
> > Why is it expensive? Not clear to me atm. And why would it be cheaper
> > for the RocksDB case?
> >
> >
> >
> >
> > About Lucas question: Not sure if we would need to do anything about it?
> > Given that we have specific RocksDB metrics, which are not available for
> > in-memory stores, why should we not have specific in-memory store
> > metrics? RocksDB metrics are also not containing "rocksdb" in their
> names?
> >
> > As long as it's properly document as "in-memory metric" (and the
> > description already mentions it explicitly) it might just be fine?
> >
> >
> >
> > MJS2: The KIP says, we would implement this only for
> > `MeteredKeyValueStore`. Why not also add it to the other store types
> > like windowed and others?
> >
> >
> > -Matthias
> >
> >
> > On 12/12/25 4:14 PM, Evan Zhou via dev wrote:
> > > Hi Lucas,
> > >
> > > Thanks for the feedback.
> > >
> > > My original intention was to use "estimate" in the metric name as the
> > > differentiator, but I agree that this is not very clear. How does
> > changing
> > > the metric name to "in-memory-state-num-keys" sound?
> > >
> > > Thanks,
> > > Evan
> > >
> > > On Thu, Dec 11, 2025 at 1:21 AM Lucas Brutschy via dev <
> > [email protected]>
> > > wrote:
> > >
> > >> Hi Evan,
> > >>
> > >> thanks for the KIP!
> > >>
> > >> If this is specific to in-memory stores, I wonder if we should add
> > >> this to the metric name? People could become confused that rocksDB
> > >> state is not showing up.
> > >>
> > >> Cheers,
> > >> Lucas
> > >>
> > >> On Thu, Dec 11, 2025 at 1:40 AM Evan Zhou via dev <
> [email protected]
> > >
> > >> wrote:
> > >>>
> > >>> Hi all,
> > >>>
> > >>> I'd like to start the discussion for KIP-1250, which adds a new
> metric
> > to
> > >>> track the size of in-memory state stores. Today, a similar metric
> > exists
> > >> in
> > >>> Kafka, but only for RocksDB, and this KIP intends to close that gap.
> > >>>
> > >>> https://cwiki.apache.org/confluence/x/noTMFw
> > >>>
> > >>> Thanks,
> > >>> Evan
> > >>
> > >
> >
> >
>

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