Hi Cheng,

Thanks for driving this, it's a needed feature to leap forward making the
stack production ready for real-world scenarios.
Design made sense to me, I have small questions:

- *Cache Coordination*: When a tablet server fails and its cached IDs
(e.g., 50,000-100,000) are lost, how does ZooKeeper ensure those IDs are
never reused? Does it maintain a global highest allocated counter?
- *Cross-bucket Dependencies*: In the example, bucket 1 gets [1-100,000]
and bucket 2 gets [100,001-200,000]. What happens if tablet server
containing bucket 1 goes down permanently? Will there always be gaps in the
sequence?
- *Race Conditions*: If two Flink workers simultaneously lookup the same
non-existent primary key, could both trigger insertIfNotExists and create
duplicate auto-increment IDs? How is this prevented?
-  How should users decide the right table.auto_inc_cache_size? Should we
put a max cap on this to avoid overburden

Best Regards,
Mehul Batra

On Fri, Sep 19, 2025 at 5:24 PM Yang Wang <[email protected]> wrote:

> Hi Cheng,
>
> Thank you for driving this FIP. I think it is a nice and important feature
> for many real-world business scenarios, and the overall design makes sense
> to me. I have just one small question:
> Regarding the client-side API design:
> ```
> Schema.newBuilder()
>         .column("uid", DataTypes.STRING())
>         .column("uid_int64", DataTypes.BIGINT())
>         .enableAutoIncrement()
>         .primaryKey("uid")
>         .build();
> ```
> If there is more than one column with INT or BIGINT type, which one would
> be the auto-increment column?
>
> Best regards,
> Yang
>
> Wang Cheng <[email protected]> 于2025年9月18日周四 22:49写道:
>
> > Hi all,
> >
> >
> > Auto-increment column is a bread-and-butter feature for improving data
> > management efficiency. It is the bedrock of many features in analytical
> > workloads—such as those in real-time unique visitor (UV) counting
> scenarios.
> >
> >
> > To implement this capability, I'd like to propose FIP-16: auto-increment
> > column [1].
> >
> >
> > Any feedback and suggestions on this proposal are welcome!
> >
> >
> > [1]:
> >
> https://cwiki.apache.org/confluence/display/FLUSS/FIP-16%3A+Auto-Increment+Column
> >
> >
> >
> >
> > Regards,
> > Cheng
> >
> >
> >
> > &nbsp;
>

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