Hi All,
@Zakelly: Gyula summarised it correctly what I meant so please treat the
content as mine.
As an addition I'm not against to add CLI at all, I'm just stating that in
some cases like this, users would like to have
a self-serving solution where they can provide SQL statements which can
trigger alerts automatically.
My personal opinion is that CLI would be beneficial for several cases. A
good example is when users want to restart job
from specific Kafka offsets which are persisted in a savepoint. For such
scenario users are more than happy since they
expect manual intervention with full control. So all in all one can count
on my +1 when CLI FLIP would come up...
BR,
G
On Thu, Mar 20, 2025 at 8:20 AM Gyula Fóra <gyula.f...@gmail.com> wrote:
> Hi!
>
> @Zakelly Lan <zakelly....@gmail.com>
> I think what Gabor means is that users want to have predefined SQL scripts
> to perform state analysis tasks to debug/identify problems.
> Such as write a SQL script that joins the metadata table with the state and
> do some analytics on it.
>
> If we have a meta table then the SQL script that can do this is fixed and
> users can trigger this on demand by simply providing a new savepoint path.
>
> If we have a different mechanism to extract metadata that is not SQL native
> then manual steps need to be executed and a custom SQL script would need to
> be written that adds the manually extracted metadata into the script.
>
> Cheers,
> Gyula
>
> On Thu, Mar 20, 2025 at 4:32 AM Zakelly Lan <zakelly....@gmail.com> wrote:
>
> > Hi all,
> >
> > Thanks for your answers! Getting everyone aligned on this topic is
> > challenging, but it’s definitely worth the effort since it will help
> > streamline things moving forward.
> >
> > @Gabor are you saying that users are using some scripts to define the SQL
> > metadata connector and get the information, right? If so, would a CLI
> tool
> > be more convenient? It's easy to invoke and can get the result swiftly.
> And
> > there should be some other systems to track the checkpoint lineage and
> > analyze if there are outliers in metadata (e.g. state size of one
> operator)
> > right? Well, maybe I missed something so please correct me if I'm wrong.
> >
> > I think the overall vision in Flink SQL is to provide a SQL native
> > > environment where we can serve complex use-cases like you would expect
> > in a
> > > regular database.
> >
> >
> > @Gyula Well, this is a good point. From the perspective of comprehensive
> > SQL experience, I'd +1 for treating metadata as data. Although I doubt if
> > there is a need for processing metadata, I won't be against a separate
> > connector.
> >
> > Regarding the CLI tool, I still think it’s worth implementing. Such a
> tool
> > could provide savepoint information before resuming from a savepoint,
> which
> > would enhance the user experience in CLI-based workflows. It would be
> good
> > if someone could implement this feature. We shouldn’t worry about whether
> > this tool might be retired in the future. Regardless of the SQL-based
> > solution we eventually adopt, this capability will remain essential for
> CLI
> > users. This is another topic.
> >
> >
> > Best,
> > Zakelly
> >
> >
> > On Thu, Mar 20, 2025 at 10:37 AM Shengkai Fang <fskm...@gmail.com>
> wrote:
> >
> > > Hi.
> > >
> > > After reading the doc[1], I think Spark provides a function for users
> to
> > > consume the metadata from the savepoint. In Flink SQL, similar
> > > functionality is implemented through Polymorphic Table Functions (PTF)
> as
> > > proposed in FLIP-440[2]. Below is a code example[3] illustrating this
> > > concept:
> > >
> > > ```
> > > public static class ScalarArgsFunction extends
> > > TestProcessTableFunctionBase {
> > > public void eval(Integer i, Boolean b) {
> > > collectObjects(i, b);
> > > }
> > > }
> > > ```
> > >
> > > ```
> > > INSERT INTO sink SELECT * FROM f(i => 42, b => CAST('TRUE' AS BOOLEAN))
> > > ``
> > >
> > > So we can add a builtin function named `read_state_metadata` to read
> > > savepoint data.
> > >
> > > Best,
> > > Shengkai
> > >
> > > [1]
> > >
> > >
> >
> https://docs.databricks.com/aws/en/structured-streaming/read-state?language=SQL
> > > [2]
> > >
> >
> https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=298781093
> > > [3]
> > >
> > >
> >
> https://github.com/apache/flink/blob/master/flink-table/flink-table-planner/src/test/java/org/apache/flink/table/planner/plan/nodes/exec/stream/ProcessTableFunctionTestPrograms.java#L140
> > >
> > > Gyula Fóra <gyula.f...@gmail.com> 于2025年3月19日周三 18:37写道：
> > >
> > > > Hi All!
> > > >
> > > > Thank you for the answers and concerns from everyone.
> > > >
> > > > On the CLI vs State Metadata Connector/Table question I would also
> like
> > > to
> > > > step back a little and look at the bigger picture.
> > > >
> > > > I think the overall vision in Flink SQL is to provide a SQL native
> > > > environment where we can serve complex use-cases like you would
> expect
> > > in a
> > > > regular database.
> > > > Most features, developments in the recent years have gone this way.
> > > >
> > > > The State Metadata Table would be a natural and straightforward fit
> > here.
> > > > So from my side, +1 for that.
> > > >
> > > > However I could understand if we are not ready to add a new
> > > > connector/format due to maintenance concerns (and in general concern
> > > about
> > > > the design).
> > > > If that's the issue then we should spend more time on the design to
> get
> > > > comfortable with the approach and seek feedback from the wider
> > community
> > > >
> > > > I am -1 for the CLI/tooling approach as that will not provide the
> > > > featureset we are looking for that is not already covered by the Java
> > > > connector. And that approach would come with the same maintenance
> > > > implications.
> > > >
> > > > Cheers
> > > > Gyula
> > > >
> > > >
> > > > On Wed, Mar 19, 2025 at 11:24 AM Gabor Somogyi <
> > > gabor.g.somo...@gmail.com>
> > > > wrote:
> > > >
> > > > > Hi Zaklely, Shengkai
> > > > >
> > > > > Several topics are going on so adding gist answers to them. When
> some
> > > > topic
> > > > > is not touched please highlight it.
> > > > >
> > > > > @Shengkai: I've read through all the previous FLIPs related
> catalogs
> > > and
> > > > if
> > > > > we would like to keep the concepts there
> > > > > then one-to-one mapping relationship between savepoint and catalog
> > is a
> > > > > reasonable direction. In short I'm happy that
> > > > > you've highlighted this and agree as a whole. I've written it down
> > > > > previously, just want to double confirm that state catalog is
> > > > > essential and planned. When we reach this point then your input is
> > more
> > > > > than welcome.
> > > > >
> > > > > @Zakelly: We've tried the CLI and separate library approaches with
> > > users
> > > > > already and these are not something which is welcome because of the
> > > > > following:
> > > > > * Users want to have automated tasks and not manual CLI/library
> > output
> > > > > parsing. This can be hacked around but our experience is negative
> on
> > > this
> > > > > because it's just brittle.
> > > > > * From development perspective It's way much bigger effort than a
> > > > connector
> > > > > (hard to test, packaging/version handling is and extra layer of
> > > > complexity,
> > > > > external FS authentication is pain for users, expecting them to
> > > download
> > > > > savepoints also)
> > > > > * Purely personal opinion but if we would find better ways later
> then
> > > > > retire a CLI is not more lightweight than retire a connector
> > > > >
> > > > > > It would be great if you give some examples on how user could
> > > leverage
> > > > > the separate connector to process the metadata.
> > > > >
> > > > > The most simplest cases:
> > > > > * give me the overgroving state uids
> > > > > * give me the not known (new or renamed) state uids
> > > > > * give me the state uids where state size drastically dropped
> compare
> > > to
> > > > a
> > > > > previous savepoint (accidental state loss)
> > > > >
> > > > > Since it was mentioned: as a general offtopic teaser, yeah it would
> > be
> > > > good
> > > > > to have some sort of checkpoint/savepoint lineage or however we
> call
> > > it.
> > > > > Since we've not yet reached this point there are no technical
> > details,
> > > > it's
> > > > > more like a vision. It's a common pattern that
> > > > > jobs are physically running but somehow the state processing is
> stuck
> > > and
> > > > > it would be good to add some way to find it out automatically.
> > > > > The important saying here is automation and not manual evaluation
> > since
> > > > > handling 10k+ jobs is just not allowing that.
> > > > >
> > > > > BR,
> > > > > G
> > > > >
> > > > >
> > > > > On Wed, Mar 19, 2025 at 6:46 AM Shengkai Fang <fskm...@gmail.com>
> > > wrote:
> > > > >
> > > > > > Hi, All.
> > > > > >
> > > > > > About State Catalog, I want to share more thoughts about this.
> > > > > >
> > > > > > In the initial design concept, I understood that a savepoint and
> a
> > > > state
> > > > > > catalog have a one-to-one mapping relationship. Each operator
> > > > corresponds
> > > > > > to a database, and the state of each operator is represented as
> > > > > individual
> > > > > > tables. The rationale behind this design is:
> > > > > >
> > > > > > *State Diversity*: An operator may involve multiple types of
> > states.
> > > > For
> > > > > > example, in our VVR design, a "multi-join" operator uses keyed
> > states
> > > > for
> > > > > > two input streams and a broadcast state for the third stream.
> This
> > > > makes
> > > > > it
> > > > > > challenging to represent all states of an operator within a
> single
> > > > table.
> > > > > > *Scalability*: Internally, an operator might have multiple keyed
> > > states
> > > > > > (e.g., value state and list state). However, large list states
> may
> > > not
> > > > > fit
> > > > > > entirely in memory. To address this, we recommend implementing
> each
> > > > state
> > > > > > as a separate table.
> > > > > >
> > > > > > To resolve the loosely coupled relationships between operator
> > states,
> > > > we
> > > > > > propose embedding predefined views within the catalog. These
> views
> > > > > simplify
> > > > > > user understanding of operator implementations and provide a more
> > > > > intuitive
> > > > > > perspective. For instance, a join operator may have multiple
> state
> > > > > > implementations (depending on whether the join key includes
> unique
> > > > > > attributes), but users primarily care about the data associated
> > with
> > > a
> > > > > > specific join key across input streams.
> > > > > >
> > > > > > Returning to the one-to-one mapping between savepoints and
> > catalogs,
> > > we
> > > > > aim
> > > > > > to manage multiple user state catalogs through a catalog store.
> > When
> > > a
> > > > > user
> > > > > > triggers a savepoint for a job on the platform:
> > > > > >
> > > > > > 1. The platform sends a REST request to the JobManager.
> > > > > > 2. Simultaneously, it registers a new state catalog in the
> catalog
> > > > store,
> > > > > > enabling immediate analysis of state data on the platform.
> > > > > > 3. Deleting a savepoint would also trigger the removal of its
> > > > associated
> > > > > > catalog.
> > > > > >
> > > > > > This vision assumes that states are self-describing or that a
> state
> > > > > > metaservice is introduced to analyze savepoint structures.
> > > > > >
> > > > > > > How can users create logic to identify differences between
> > multiple
> > > > > > savepoints?
> > > > > >
> > > > > > Since savepoints and state catalogs are one-to-one mapped, users
> > can
> > > > > query
> > > > > > metadata via their respective catalogs. For example:
> > > > > >
> > > > > > 1. `savepoint-${id}`.`system`.`metadata_table`.`<operator-name>`
> > > > provides
> > > > > > operator-specific metadata (e.g., state size, type).
> > > > > > 2. Comparing metadata tables (e.g., schema versions, state entry
> > > > counts)
> > > > > > across catalogs reveals structural or quantitative differences.
> > > > > > 3. For deeper analysis, users could write SQL queries to compare
> > > > specific
> > > > > > state partitions or leverage the metaservice to track state
> > evolution
> > > > > > (e.g., added/removed operators, modified state configurations).
> > > > > >
> > > > > > If we plan to introduce a state catalog in the future, I would
> lean
> > > > > toward
> > > > > > using metadata tables. If a utility tool can address the
> challenges
> > > we
> > > > > > face, could we avoid introducing an additional connector?
> > > > > >
> > > > > > Best,
> > > > > > Shengkai
> > > > > >
> > > > > > Gyula Fóra <gyula.f...@gmail.com> 于2025年3月17日周一 20:25写道：
> > > > > >
> > > > > > > Hi All!
> > > > > > >
> > > > > > > Without going into too much detail here are my 2 cents
> regarding
> > > the
> > > > > > > virtual column / catalog metadata / table (connector)
> discussion
> > > for
> > > > > the
> > > > > > > State metadata.
> > > > > > >
> > > > > > > State metadata such as the types of states, their properties,
> > > names,
> > > > > > sizes
> > > > > > > etc are all valuable information that can be used to enrich the
> > > > > > > computations we do on state.
> > > > > > > We can either analyze it standalone (such as discover
> anomalies,
> > > for
> > > > > > large
> > > > > > > jobs with many states), across multiple savepoints (discover
> how
> > > > state
> > > > > > > changed over time) or by joining it with keyed or non-keyed
> state
> > > > data
> > > > > to
> > > > > > > serve more complex queries on the state.
> > > > > > >
> > > > > > > The only solution that seems to serve all these use-cases and
> > > > > > requirements
> > > > > > > in a straightforward and SQL canonical way is to simply expose
> > the
> > > > > state
> > > > > > > metadata as a separate table. This is a metadata table but you
> > can
> > > > also
> > > > > > > think of it as data table, it makes no practical difference
> here.
> > > > > > >
> > > > > > > Once we have a catalog later, the catalog can offer this table
> > out
> > > of
> > > > > the
> > > > > > > box, the same way databases provide metadata tables. For this
> to
> > > work
> > > > > > > however we need another, simpler connector that creates this
> > table.
> > > > > > >
> > > > > > > +1 for state metadata as a separate connector/table, instead of
> > > > adding
> > > > > > > virtual columns and adhoc catalog metadata that is hard to use
> > in a
> > > > > large
> > > > > > > number of queries.
> > > > > > >
> > > > > > > Cheers,
> > > > > > > Gyula
> > > > > > >
> > > > > > > On Mon, Mar 17, 2025 at 12:44 PM Gabor Somogyi <
> > > > > > gabor.g.somo...@gmail.com>
> > > > > > > wrote:
> > > > > > >
> > > > > > > > 1. State TTL for Value Columns
> > > > > > > >
> > > > > > > > > I’m planning on adding this, and we may collaborate on it
> in
> > > the
> > > > > > > future.
> > > > > > > >
> > > > > > > > +1 on this, just ping me.
> > > > > > > >
> > > > > > > > 2. Metadata Table vs. Metadata Column
> > > > > > > >
> > > > > > > > After some code digging and POC all I can say that with heavy
> > > > effort
> > > > > we
> > > > > > > can
> > > > > > > > maybe add such changes that we're able to show metadata of a
> > > > > savepoint
> > > > > > > from
> > > > > > > > catalog.
> > > > > > > > I'm not against that but from user perspective this has
> limited
> > > > > value,
> > > > > > > let
> > > > > > > > me explain why.
> > > > > > > >
> > > > > > > > From high level perspective I see the following which I see
> > > > agreement
> > > > > > on:
> > > > > > > > * We should have a catalog which is representing one or more
> > jobs
> > > > > > > savepoint
> > > > > > > > data set (future plan)
> > > > > > > > * Savepoints should be able to be registered in the catalog
> > which
> > > > are
> > > > > > > then
> > > > > > > > databases (future plan)
> > > > > > > > * There must be a possiblity to create tables from databases
> > > where
> > > > > > users
> > > > > > > > can read state data (exists already)
> > > > > > > >
> > > > > > > > In terms of metadata, If I understand correctly then the
> > > suggested
> > > > > > > approach
> > > > > > > > would be to access
> > > > > > > > it from the catalog describe command, right? Adding that info
> > > when
> > > > > > > specific
> > > > > > > > database describe command
> > > > > > > > is executed could be done.
> > > > > > > >
> > > > > > > > The question is for instance how can users create such a
> logic
> > > that
> > > > > > tells
> > > > > > > > them what is
> > > > > > > > the difference between multiple savepoints?
> > > > > > > > Just to give some examples:
> > > > > > > > * per operator size changes between savepoints
> > > > > > > > * show values from operator data where state size reaches a
> > > > boundary
> > > > > > > > * in general "find which checkpoint ruined things" is quite
> > > common
> > > > > > > pattern
> > > > > > > > What I would like to highlight here is that from Flink point
> of
> > > > view
> > > > > > the
> > > > > > > > metadata can be
> > > > > > > > considered as a static side output information but for users
> > > these
> > > > > > values
> > > > > > > > are actual real data
> > > > > > > > where logic is planned to build around.
> > > > > > > >
> > > > > > > > > The metadata is more like one-time information instead of a
> > > > > streaming
> > > > > > > > data that changes all
> > > > > > > > the time, so a single connector seems to be an overkill.
> > > > > > > >
> > > > > > > > State data is also static within a savepoint and that's the
> > > reason
> > > > > why
> > > > > > > the
> > > > > > > > state processor API is working in batch mode.
> > > > > > > > When we handle multiple checkpoints in a streaming fashion
> then
> > > > this
> > > > > > can
> > > > > > > be
> > > > > > > > viewed from another angle.
> > > > > > > >
> > > > > > > > We can come up with more lightweight solution other than a
> new
> > > > > > connector
> > > > > > > > but enforcing users to parse the catalog
> > > > > > > > describe command output in order to compare multiple
> savepoints
> > > > > doesn't
> > > > > > > > sound smooth user experience.
> > > > > > > > Honestly I've no other idea how exposing metadata as real
> user
> > > data
> > > > > so
> > > > > > > > waiting on other approaches.
> > > > > > > >
> > > > > > > > BR,
> > > > > > > > G
> > > > > > > >
> > > > > > > >
> > > > > > > > On Thu, Mar 13, 2025 at 2:44 AM Shengkai Fang <
> > fskm...@gmail.com
> > > >
> > > > > > wrote:
> > > > > > > >
> > > > > > > > > Looking forward to hearing the good news!
> > > > > > > > >
> > > > > > > > > Best,
> > > > > > > > > Shengkai
> > > > > > > > >
> > > > > > > > > Gabor Somogyi <gabor.g.somo...@gmail.com> 于2025年3月12日周三
> > > 22:24写道：
> > > > > > > > >
> > > > > > > > > > Thanks for both the valuable input!
> > > > > > > > > >
> > > > > > > > > > Let me take a closer look at the suggestions, like the
> > > Catalog
> > > > > > > > > capabilities
> > > > > > > > > > and possibility of embedding TypeInformation or
> > > > > > > > > > StateDescriptor metadata directly into the raw state
> > files...
> > > > > > > > > >
> > > > > > > > > > BR,
> > > > > > > > > > G
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > On Wed, Mar 12, 2025 at 8:17 AM Shengkai Fang <
> > > > fskm...@gmail.com
> > > > > >
> > > > > > > > wrote:
> > > > > > > > > >
> > > > > > > > > > > Thanks for Zakelly's clarification.
> > > > > > > > > > >
> > > > > > > > > > > 1. State TTL for Value Columns
> > > > > > > > > > >
> > > > > > > > > > > +1 to delay the discussion about this.
> > > > > > > > > > >
> > > > > > > > > > > 2. Metadata Table vs. Metadata Column
> > > > > > > > > > >
> > > > > > > > > > > I’d like to share my perspective on the State Catalog
> > > > proposal.
> > > > > > > While
> > > > > > > > > > > introducing this capability is beneficial, there is a
> > > > blocker:
> > > > > > the
> > > > > > > > > > current
> > > > > > > > > > > StateBackend architecture does not permit operators to
> > > encode
> > > > > > > > > > > TypeInformation into the state—it only preserves the
> > > > > Serializer.
> > > > > > > This
> > > > > > > > > > > limitation creates an asymmetry, as operators alone
> > retain
> > > > > > > knowledge
> > > > > > > > of
> > > > > > > > > > the
> > > > > > > > > > > data structure’s schema.
> > > > > > > > > > >
> > > > > > > > > > > To address this, I suggest allowing operators to embed
> > > > > > > > TypeInformation
> > > > > > > > > or
> > > > > > > > > > > StateDescriptor metadata directly into the raw state
> > files.
> > > > > Such
> > > > > > a
> > > > > > > > > design
> > > > > > > > > > > would enable the Catalog to:
> > > > > > > > > > >
> > > > > > > > > > > 1. Parse state files and programmatically derive the
> > schema
> > > > and
> > > > > > > > > > structural
> > > > > > > > > > > guarantees for each state.
> > > > > > > > > > > 2. Leverage existing Flink Table utilities, such as
> > > > > > > > > > > LegacyTypeInfoDataTypeConverter (in
> > > > > > > > > org.apache.flink.table.types.utils),
> > > > > > > > > > to
> > > > > > > > > > > bridge TypeInformation and DataType conversions.
> > > > > > > > > > >
> > > > > > > > > > > If we can not store the TypeInformation or
> > StateDescriptor
> > > > into
> > > > > > the
> > > > > > > > raw
> > > > > > > > > > > state files, I am +1 for this FLIP to use metadata
> column
> > > to
> > > > > > > retrieve
> > > > > > > > > > > information.
> > > > > > > > > > >
> > > > > > > > > > > Best,
> > > > > > > > > > > Shengkai
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > Zakelly Lan <zakelly....@gmail.com> 于2025年3月12日周三
> > 12:43写道：
> > > > > > > > > > >
> > > > > > > > > > > > Hi Gabor and Shengkai,
> > > > > > > > > > > >
> > > > > > > > > > > > Thanks for sharing your thoughts! This is a long
> > > discussion
> > > > > and
> > > > > > > > sorry
> > > > > > > > > > for
> > > > > > > > > > > > the late reply (I'm busy catching up with release 2.0
> > > these
> > > > > > > days).
> > > > > > > > > > > >
> > > > > > > > > > > > 1. State TTL for Value Columns
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > Let me first clarify your thoughts to ensure I
> > understand
> > > > > > > > correctly.
> > > > > > > > > > > IIUC,
> > > > > > > > > > > > there is no persistent configuration for state TTL in
> > the
> > > > > > > > checkpoint.
> > > > > > > > > > > While
> > > > > > > > > > > > you can infer that TTL is enabled by reading the
> > > > serializer,
> > > > > > the
> > > > > > > > > > > checkpoint
> > > > > > > > > > > > itself only stores the last access time for each
> value.
> > > So
> > > > > the
> > > > > > > only
> > > > > > > > > > thing
> > > > > > > > > > > > we can show is the last access time for each value.
> But
> > > it
> > > > is
> > > > > > not
> > > > > > > > > > > required
> > > > > > > > > > > > for all state backends to store this, as they may
> > > directly
> > > > > > store
> > > > > > > > the
> > > > > > > > > > > > expired time. This will also increase the difficulty
> of
> > > > > > > > > implementation
> > > > > > > > > > &
> > > > > > > > > > > > maintenance.
> > > > > > > > > > > >
> > > > > > > > > > > > This once again reiterates the importance of unified
> > > > metadata
> > > > > > for
> > > > > > > > > > > > checkpoints. I’m planning on adding this, and we may
> > > > > > collaborate
> > > > > > > on
> > > > > > > > > it
> > > > > > > > > > in
> > > > > > > > > > > > the future.
> > > > > > > > > > > >
> > > > > > > > > > > > 2. Metadata Table vs. Metadata Column
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > I'm not in favor of adding a new connector for
> > metadata.
> > > > The
> > > > > > > > metadata
> > > > > > > > > > is
> > > > > > > > > > > > more like one-time information instead of a streaming
> > > data
> > > > > that
> > > > > > > > > changes
> > > > > > > > > > > all
> > > > > > > > > > > > the time, so a single connector seems to be an
> > overkill.
> > > It
> > > > > is
> > > > > > > not
> > > > > > > > > easy
> > > > > > > > > > > to
> > > > > > > > > > > > withdraw a connector if we have a better solution in
> > > > future.
> > > > > > I'm
> > > > > > > > not
> > > > > > > > > > > > familiar with current Catalog capabilities, and if it
> > > could
> > > > > > > extract
> > > > > > > > > and
> > > > > > > > > > > > show some operator-level information from savepoint,
> > that
> > > > > would
> > > > > > > be
> > > > > > > > > > great.
> > > > > > > > > > > >
> > > > > > > > > > > > If the Catalog can't do that, I would consider the
> > > current
> > > > > FLIP
> > > > > > > to
> > > > > > > > > be a
> > > > > > > > > > > > compromise solution.
> > > > > > > > > > > >
> > > > > > > > > > > > And if we have that unified metadata for
> > > > checkpoint/savepoint
> > > > > > in
> > > > > > > > > > future,
> > > > > > > > > > > we
> > > > > > > > > > > > may directly register savepoint in catalog, and
> create
> > a
> > > > > source
> > > > > > > > > without
> > > > > > > > > > > > specifying complex columns, as well as describe the
> > > > savepoint
> > > > > > > > catalog
> > > > > > > > > > to
> > > > > > > > > > > > get the metadata. That's a good solution in my mind.
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > Best,
> > > > > > > > > > > > Zakelly
> > > > > > > > > > > >
> > > > > > > > > > > > On Wed, Mar 12, 2025 at 10:35 AM Shengkai Fang <
> > > > > > > fskm...@gmail.com>
> > > > > > > > > > > wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > > Hi Gabor,
> > > > > > > > > > > > >
> > > > > > > > > > > > > > 2. Adding a new connector with
> `savepoint-metadata`
> > > > > > > > > > > > >
> > > > > > > > > > > > > I would argue against introducing a new connector
> > type
> > > > > named
> > > > > > > > > > > > > savepoint-metadata, as the existing Catalog
> mechanism
> > > can
> > > > > > > > > inherently
> > > > > > > > > > > > > provide the necessary connector factory
> capabilities.
> > > > I’ve
> > > > > > > > detailed
> > > > > > > > > > > this
> > > > > > > > > > > > > proposal in branch[1]. Please take a moment to
> review
> > > it.
> > > > > > > > > > > > >
> > > > > > > > > > > > > If we introduce a connector named
> > `savepoint-metadata`,
> > > > it
> > > > > > > means
> > > > > > > > > user
> > > > > > > > > > > can
> > > > > > > > > > > > > create a temporary table with connector
> > > > > `savepoint-metadata`
> > > > > > > and
> > > > > > > > > the
> > > > > > > > > > > > > connector needs to check whether table schema is
> same
> > > to
> > > > > the
> > > > > > > > schema
> > > > > > > > > > we
> > > > > > > > > > > > > proposed in the FLIP. On the other hand, it's not
> > easy
> > > > work
> > > > > > for
> > > > > > > > > > others
> > > > > > > > > > > to
> > > > > > > > > > > > > users a metadata table with same schema.
> > > > > > > > > > > > >
> > > > > > > > > > > > > [1]
> > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> https://github.com/apache/flink/compare/master...fsk119:flink:state-metadata?expand=1#diff-712a7bc92fe46c405fb0e61b475bb2a005cb7a72bab7df28bbb92744bcb5f465R63
> > > > > > > > > > > > >
> > > > > > > > > > > > > Best,
> > > > > > > > > > > > > Shengkai
> > > > > > > > > > > > >
> > > > > > > > > > > > > Gabor Somogyi <gabor.g.somo...@gmail.com>
> > > 于2025年3月11日周二
> > > > > > > 16:56写道：
> > > > > > > > > > > > >
> > > > > > > > > > > > > > Hi Shengkai,
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > > 1. State TTL for Value Columns
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > From directional perspective I agree your idea
> how
> > it
> > > > can
> > > > > > be
> > > > > > > > > > > > implemented.
> > > > > > > > > > > > > > Previously I've mentioned that TTL information is
> > not
> > > > > > exposed
> > > > > > > > on
> > > > > > > > > > the
> > > > > > > > > > > > > state
> > > > > > > > > > > > > > processor API (which the SQL state connector uses
> > to
> > > > read
> > > > > > > data)
> > > > > > > > > > > > > > and unless somebody show me the opposite this
> FLIP
> > is
> > > > not
> > > > > > > going
> > > > > > > > > to
> > > > > > > > > > > > > address
> > > > > > > > > > > > > > this to avoid feature creep. Our users are also
> > > > > interested
> > > > > > in
> > > > > > > > TTL
> > > > > > > > > > so
> > > > > > > > > > > > > > sooner or later we're going to expose it, this is
> > > > matter
> > > > > of
> > > > > > > > > > > scheduling.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > > 2. Adding a new connector with
> > `savepoint-metadata`
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Not sure I understand your point at all related
> > > > > > StateCatalog.
> > > > > > > > > First
> > > > > > > > > > > of
> > > > > > > > > > > > > all
> > > > > > > > > > > > > > I can't agree more that StateCatalog is needed
> and
> > > is a
> > > > > > > planned
> > > > > > > > > > > > building
> > > > > > > > > > > > > > block in an upcoming
> > > > > > > > > > > > > > FLIP but not sure how can it help now? No matter
> > > what,
> > > > > your
> > > > > > > > > > knowledge
> > > > > > > > > > > > is
> > > > > > > > > > > > > > essential when we add StateCatalog. Let me expose
> > my
> > > > > > > > > understanding
> > > > > > > > > > in
> > > > > > > > > > > > > this
> > > > > > > > > > > > > > area:
> > > > > > > > > > > > > > * First we need create table statements to access
> > > state
> > > > > > data
> > > > > > > > and
> > > > > > > > > > > > metadata
> > > > > > > > > > > > > > * When we have that then we can add StateCatalog
> > > which
> > > > > > could
> > > > > > > > > > > > potentially
> > > > > > > > > > > > > > ease the life of users by for ex. giving
> > > off-the-shelf
> > > > > > tables
> > > > > > > > > > without
> > > > > > > > > > > > > > sweating with create table statements
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > User expectations:
> > > > > > > > > > > > > > * See state data (this is fulfilled with the
> > existing
> > > > > > > > connector)
> > > > > > > > > > > > > > * See metadata about state data like TTL (this
> can
> > be
> > > > > added
> > > > > > > as
> > > > > > > > > > > metadata
> > > > > > > > > > > > > > column as you suggested since it belongs to the
> > data)
> > > > > > > > > > > > > > * See metadata about operators (this can be added
> > > from
> > > > > > > > > > > > > savepoint-metadata)
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Important to highlight that state data table
> format
> > > > > differs
> > > > > > > > from
> > > > > > > > > > > state
> > > > > > > > > > > > > > metadata table format. Namely one table has rows
> > for
> > > > > state
> > > > > > > > values
> > > > > > > > > > and
> > > > > > > > > > > > > > another has rows for operators, right?
> > > > > > > > > > > > > > I think that's the reason why you've pinpointed
> out
> > > > that
> > > > > > the
> > > > > > > > > > > suggested
> > > > > > > > > > > > > > metadata columns are somewhat clunky.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > As a conclusion I agree to add ${state-name}_ttl
> > > > metadata
> > > > > > > > column
> > > > > > > > > > > later
> > > > > > > > > > > > on
> > > > > > > > > > > > > > since it belongs to the state value and adding a
> > new
> > > > > table
> > > > > > > type
> > > > > > > > > > (like
> > > > > > > > > > > > you
> > > > > > > > > > > > > > suggested similar to PG [1])
> > > > > > > > > > > > > > for metadata. Please see how Spark does that too
> > [2].
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > If you have better approach then please elaborate
> > > with
> > > > > more
> > > > > > > > > details
> > > > > > > > > > > and
> > > > > > > > > > > > > > help me to understand your point.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Up until now we've seen even in TB savepoints
> > that
> > > > the
> > > > > > > number
> > > > > > > > > of
> > > > > > > > > > > keys
> > > > > > > > > > > > > can
> > > > > > > > > > > > > > > be extremely huge but not the per key state
> > itself.
> > > > > > > > > > > > > > > But again, this is a good feature as-is and can
> > be
> > > > > > handled
> > > > > > > > in a
> > > > > > > > > > > > > separate
> > > > > > > > > > > > > > > jira.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > I've just created
> > > > > > > > > > https://issues.apache.org/jira/browse/FLINK-37456.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > [1]
> > > > > > > > https://www.postgresql.org/docs/current/view-pg-tables.html
> > > > > > > > > > > > > > [2]
> > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> https://www.databricks.com/blog/announcing-state-reader-api-new-statestore-data-source
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > BR,
> > > > > > > > > > > > > > G
> > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > On Tue, Mar 11, 2025 at 3:55 AM Shengkai Fang <
> > > > > > > > fskm...@gmail.com
> > > > > > > > > >
> > > > > > > > > > > > wrote:
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Hi, Gabor. Thanks for your response.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > 1. State TTL for Value Columns
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Thank you for addressing the limitations here.
> > > > > However, I
> > > > > > > > > believe
> > > > > > > > > > > it
> > > > > > > > > > > > > > would
> > > > > > > > > > > > > > > be beneficial to further clarify the API in
> this
> > > FLIP
> > > > > > > > regarding
> > > > > > > > > > how
> > > > > > > > > > > > > users
> > > > > > > > > > > > > > > can specify the TTL column.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > One potential approach that comes to mind is
> > using
> > > a
> > > > > > > > > standardized
> > > > > > > > > > > > > naming
> > > > > > > > > > > > > > > convention such as ${state-name}_ttl for the
> > > metadata
> > > > > > > column
> > > > > > > > > that
> > > > > > > > > > > > > defines
> > > > > > > > > > > > > > > the TTL value. In terms of implementation, the
> > > > > > > > > > listReadableMetadata
> > > > > > > > > > > > > > > function could:
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > 1. Read the table’s columns and configuration,
> > > > > > > > > > > > > > > 2. Extract all defined state names, and
> > > > > > > > > > > > > > > 3. Return a structured list of metadata entries
> > > > > formatted
> > > > > > > as
> > > > > > > > > > > > > > > ${state-name}_ttl.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > WDYT?
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > 2. Adding a new connector with
> > > `savepoint-metadata`
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Introducing a new connector type at this stage
> > may
> > > > > > > > > unnecessarily
> > > > > > > > > > > > > > complicate
> > > > > > > > > > > > > > > the system. Given that every table already
> > belongs
> > > > to a
> > > > > > > > > Catalog,
> > > > > > > > > > > > which
> > > > > > > > > > > > > is
> > > > > > > > > > > > > > > designed to provide a Factory for building
> source
> > > or
> > > > > sink
> > > > > > > > > > > > connectors, I
> > > > > > > > > > > > > > > propose integrating a dedicated StateCatalog
> > > instead.
> > > > > > This
> > > > > > > > > > approach
> > > > > > > > > > > > > would
> > > > > > > > > > > > > > > allow us to:
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > 1. Leverage the Catalog’s existing capabilities
> > to
> > > > > manage
> > > > > > > TTL
> > > > > > > > > > > > metadata
> > > > > > > > > > > > > > > (e.g., state names and TTL logic) without
> > > duplicating
> > > > > > > > > > > functionality.
> > > > > > > > > > > > > > > 2. Provide a unified interface for connector
> > > > > > instantiation
> > > > > > > > and
> > > > > > > > > > > > metadata
> > > > > > > > > > > > > > > handling through the Catalog’s Factory pattern.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Would this design decision better align with
> our
> > > > > > > > architecture’s
> > > > > > > > > > > > > > > extensibility and reduce redundancy?
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Up until now we've seen even in TB savepoints
> > > that
> > > > > the
> > > > > > > > number
> > > > > > > > > > of
> > > > > > > > > > > > keys
> > > > > > > > > > > > > > can
> > > > > > > > > > > > > > > > be extremely huge but not the per key state
> > > itself.
> > > > > > > > > > > > > > > > But again, this is a good feature as-is and
> can
> > > be
> > > > > > > handled
> > > > > > > > > in a
> > > > > > > > > > > > > > separate
> > > > > > > > > > > > > > > > jira.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > +1 for a separate jira.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Best,
> > > > > > > > > > > > > > > Shengkai
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Gabor Somogyi <gabor.g.somo...@gmail.com>
> > > > > 于2025年3月10日周一
> > > > > > > > > 19:05写道：
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Hi Shengkai,
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Please see my comments inline.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > BR,
> > > > > > > > > > > > > > > > G
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > On Mon, Mar 3, 2025 at 7:07 AM Shengkai Fang
> <
> > > > > > > > > > fskm...@gmail.com>
> > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Hi, Gabor. Thanks for your the FLIP. I have
> > > some
> > > > > > > > questions
> > > > > > > > > > > about
> > > > > > > > > > > > > the
> > > > > > > > > > > > > > > > FLIP:
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > 1. State TTL for Value Columns
> > > > > > > > > > > > > > > > > How can users retrieve the state TTL
> > > > (Time-to-Live)
> > > > > > for
> > > > > > > > > each
> > > > > > > > > > > > value
> > > > > > > > > > > > > > > > column?
> > > > > > > > > > > > > > > > > From my understanding of the current
> design,
> > it
> > > > > seems
> > > > > > > > that
> > > > > > > > > > this
> > > > > > > > > > > > > > > > > functionality is not supported. Could you
> > > clarify
> > > > > if
> > > > > > > > there
> > > > > > > > > > are
> > > > > > > > > > > > > plans
> > > > > > > > > > > > > > to
> > > > > > > > > > > > > > > > > address this limitation?
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Since the state processor API is not yet
> > exposing
> > > > > this
> > > > > > > > > > > information
> > > > > > > > > > > > > this
> > > > > > > > > > > > > > > > would require several steps.
> > > > > > > > > > > > > > > > First, the state processor API support needs
> to
> > > be
> > > > > > added
> > > > > > > > > which
> > > > > > > > > > > can
> > > > > > > > > > > > be
> > > > > > > > > > > > > > > then
> > > > > > > > > > > > > > > > exposed on the SQL API.
> > > > > > > > > > > > > > > > This is definitely a future improvement which
> > is
> > > > > useful
> > > > > > > and
> > > > > > > > > can
> > > > > > > > > > > be
> > > > > > > > > > > > > > > handled
> > > > > > > > > > > > > > > > in a separate jira.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > 2. Metadata Table vs. Metadata Column
> > > > > > > > > > > > > > > > > The metadata information described in the
> > FLIP
> > > > > > appears
> > > > > > > to
> > > > > > > > > be
> > > > > > > > > > > > > intended
> > > > > > > > > > > > > > > to
> > > > > > > > > > > > > > > > > describe the state files stored at a
> specific
> > > > > > location.
> > > > > > > > To
> > > > > > > > > > me,
> > > > > > > > > > > > this
> > > > > > > > > > > > > > > > concept
> > > > > > > > > > > > > > > > > aligns more closely with system tables like
> > > > > pg_tables
> > > > > > > in
> > > > > > > > > > > > PostgreSQL
> > > > > > > > > > > > > > [1]
> > > > > > > > > > > > > > > > or
> > > > > > > > > > > > > > > > > the INFORMATION_SCHEMA in MySQL [2].
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Adding a new connector with
> > `savepoint-metadata`
> > > > is a
> > > > > > > > > > possibility
> > > > > > > > > > > > > where
> > > > > > > > > > > > > > > we
> > > > > > > > > > > > > > > > can create such functionality.
> > > > > > > > > > > > > > > > I'm not against that, just want to have a
> > common
> > > > > > > agreement
> > > > > > > > > that
> > > > > > > > > > > we
> > > > > > > > > > > > > > would
> > > > > > > > > > > > > > > > like to move that direction.
> > > > > > > > > > > > > > > > (As a side note not just PG but Spark also
> has
> > > > > similar
> > > > > > > > > approach
> > > > > > > > > > > > and I
> > > > > > > > > > > > > > > > basically like the idea).
> > > > > > > > > > > > > > > > If we would go that direction savepoint
> > metadata
> > > > can
> > > > > be
> > > > > > > > > reached
> > > > > > > > > > > in
> > > > > > > > > > > > a
> > > > > > > > > > > > > > way
> > > > > > > > > > > > > > > > that one row would represent
> > > > > > > > > > > > > > > > an operator with it's values something like
> > this:
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> ┌─────────┬─────────┬─────────┬─────────┬─────────┬─────────┬─────────┬────────┐
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> │operatorN│operatorU│operatorH│paralleli│maxParall│subtaskSt│coordinat│totalSta│
> > > > > > > > > > > > > > > > │ame │id │ash │sm
> │elism
> > > > > > > > > > > > > > > > │atesCount│orStateSi│tesSizeI│
> > > > > > > > > > > > > > > > │ │ │ │ │
> > > │
> > > > > > > > > > > > > > > > │zeInBytes│nBytes │
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> ├─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼────────┤
> > > > > > > > > > > > > > > > │Source: │datagen-s│47aee9439│2 │128
> > > > │2
> > > > > > > > > │16
> > > > > > > > > > > > > > > > │546 │
> > > > > > > > > > > > > > > > │datagen-s│ource-uid│4d6ea26e2│ │
> > > │
> > > > > > > > │
> > > > > > > > > > > > > │
> > > > > > > > > > > > > > > > │
> > > > > > > > > > > > > > > > │ource │ │d544bef0a│ │
> > > │
> > > > > > > > │
> > > > > > > > > > > > > │
> > > > > > > > > > > > > > > > │
> > > > > > > > > > > > > > > > │ │ │37bb5 │ │
> > > │
> > > > > > > > │
> > > > > > > > > > > > > │
> > > > > > > > > > > > > > > > │
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> ├─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼────────┤
> > > > > > > > > > > > > > > > │long-udf-│long-udf-│6ed3f40bf│2 │128
> > > > │2
> > > > > > > > > │0
> > > > > > > > > > > > > > │0
> > > > > > > > > > > > > > > > │
> > > > > > > > > > > > > > > > │with-mast│with-mast│f3c8dfcdf│ │
> > > │
> > > > > > > > │
> > > > > > > > > > > > > │
> > > > > > > > > > > > > > > > │
> > > > > > > > > > > > > > > > │er-hook │er-hook-u│cb95128a1│ │
> > > │
> > > > > > > > │
> > > > > > > > > > > > > │
> > > > > > > > > > > > > > > > │
> > > > > > > > > > > > > > > > │ │id │018f1 │ │
> > > │
> > > > > > > > │
> > > > > > > > > > > > > │
> > > > > > > > > > > > > > > > │
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> ├─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼────────┤
> > > > > > > > > > > > > > > > │value-pro│value-pro│ca4f5fe9a│2 │128
> > > > │2
> > > > > > > > > │0
> > > > > > > > > > > > > > > > │40726 │
> > > > > > > > > > > > > > > > │cess │cess-uid │637b656f0│ │
> > > │
> > > > > > > > │
> > > > > > > > > > > > > │
> > > > > > > > > > > > > > > > │
> > > > > > > > > > > > > > > > │ │ │9ea78b3e7│ │
> > > │
> > > > > > > > │
> > > > > > > > > > > > > │
> > > > > > > > > > > > > > > > │
> > > > > > > > > > > > > > > > │ │ │a15b9 │ │
> > > │
> > > > > > > > │
> > > > > > > > > > > > > │
> > > > > > > > > > > > > > > > │
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> ├─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼────────┤
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > This table can then be joined with the
> actually
> > > > > > existing
> > > > > > > > > > > > `savepoint`
> > > > > > > > > > > > > > > > connector created tables based on UID hash
> > (which
> > > > is
> > > > > > > unique
> > > > > > > > > and
> > > > > > > > > > > > > always
> > > > > > > > > > > > > > > > exists).
> > > > > > > > > > > > > > > > This would mean that the already existing
> table
> > > > would
> > > > > > > need
> > > > > > > > > > only a
> > > > > > > > > > > > > > single
> > > > > > > > > > > > > > > > metadata column which is the UID hash.
> > > > > > > > > > > > > > > > WDYT?
> > > > > > > > > > > > > > > > @zakelly, plz share your thoughts too.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > If we opt to use metadata columns, every
> > record
> > > > in
> > > > > > the
> > > > > > > > > table
> > > > > > > > > > > > would
> > > > > > > > > > > > > > end
> > > > > > > > > > > > > > > up
> > > > > > > > > > > > > > > > > having identical values for these columns
> > > (please
> > > > > > > correct
> > > > > > > > > me
> > > > > > > > > > if
> > > > > > > > > > > > I’m
> > > > > > > > > > > > > > > > > mistaken). On the other hand, the state
> > > connector
> > > > > > > > requires
> > > > > > > > > > > users
> > > > > > > > > > > > to
> > > > > > > > > > > > > > > > specify
> > > > > > > > > > > > > > > > > an operator UID or operator UID hash, after
> > > which
> > > > > it
> > > > > > > > > outputs
> > > > > > > > > > > > > > > user-defined
> > > > > > > > > > > > > > > > > values in its records. This approach feels
> > > > somewhat
> > > > > > > > > redundant
> > > > > > > > > > > to
> > > > > > > > > > > > > me.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > If we would add a new `savepoint-metadata`
> > > > connector
> > > > > > then
> > > > > > > > > this
> > > > > > > > > > > can
> > > > > > > > > > > > be
> > > > > > > > > > > > > > > > addressed.
> > > > > > > > > > > > > > > > On the other hand UID and UID hash are having
> > > > > either-or
> > > > > > > > > > > > relationship
> > > > > > > > > > > > > > from
> > > > > > > > > > > > > > > > config perspective,
> > > > > > > > > > > > > > > > so when a user provides the UID then he/she
> can
> > > be
> > > > > > > > interested
> > > > > > > > > > in
> > > > > > > > > > > > the
> > > > > > > > > > > > > > hash
> > > > > > > > > > > > > > > > for further calculations
> > > > > > > > > > > > > > > > (the whole Flink internals are depending on
> the
> > > > > hash).
> > > > > > > > > Printing
> > > > > > > > > > > out
> > > > > > > > > > > > > the
> > > > > > > > > > > > > > > > human readable UID
> > > > > > > > > > > > > > > > is an explicit requirement from the user side
> > > > because
> > > > > > > > hashes
> > > > > > > > > > are
> > > > > > > > > > > > not
> > > > > > > > > > > > > > > human
> > > > > > > > > > > > > > > > readable.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > 3. Handling LIST and MAP States in the
> State
> > > > > > Connector
> > > > > > > > > > > > > > > > > I have concerns about how the current
> design
> > > > > handles
> > > > > > > LIST
> > > > > > > > > and
> > > > > > > > > > > MAP
> > > > > > > > > > > > > > > states.
> > > > > > > > > > > > > > > > > Specifically, the state connector uses
> Flink
> > > > SQL’s
> > > > > > MAP
> > > > > > > > and
> > > > > > > > > > > ARRAY
> > > > > > > > > > > > > > types,
> > > > > > > > > > > > > > > > > which implies that it attempts to load
> entire
> > > MAP
> > > > > or
> > > > > > > LIST
> > > > > > > > > > > states
> > > > > > > > > > > > > into
> > > > > > > > > > > > > > > > > memory.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > However, in many real-world scenarios,
> these
> > > > states
> > > > > > can
> > > > > > > > > grow
> > > > > > > > > > > very
> > > > > > > > > > > > > > > large.
> > > > > > > > > > > > > > > > > Typically, the state API addresses this by
> > > > > providing
> > > > > > an
> > > > > > > > > > > iterator
> > > > > > > > > > > > to
> > > > > > > > > > > > > > > > > traverse elements within the state
> > > incrementally.
> > > > > I’m
> > > > > > > > > unsure
> > > > > > > > > > > > > whether
> > > > > > > > > > > > > > > I’ve
> > > > > > > > > > > > > > > > > missed something in FLIP-496 or FLIP-512,
> but
> > > it
> > > > > > seems
> > > > > > > > that
> > > > > > > > > > the
> > > > > > > > > > > > > > current
> > > > > > > > > > > > > > > > > design might struggle with scalability in
> > such
> > > > > cases.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > You see it good, the current implementation
> > keeps
> > > > > state
> > > > > > > > for a
> > > > > > > > > > > > single
> > > > > > > > > > > > > > key
> > > > > > > > > > > > > > > in
> > > > > > > > > > > > > > > > memory.
> > > > > > > > > > > > > > > > Back in the days we've considered this
> > potential
> > > > > issue
> > > > > > > and
> > > > > > > > > > > > concluded
> > > > > > > > > > > > > > that
> > > > > > > > > > > > > > > > this is not necessarily
> > > > > > > > > > > > > > > > needed for the initial version and can be
> done
> > > as a
> > > > > > later
> > > > > > > > > > > > > improvement.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Up until now we've seen even in TB savepoints
> > > that
> > > > > the
> > > > > > > > number
> > > > > > > > > > of
> > > > > > > > > > > > keys
> > > > > > > > > > > > > > can
> > > > > > > > > > > > > > > > be extremely huge but not the per key state
> > > itself.
> > > > > > > > > > > > > > > > But again, this is a good feature as-is and
> can
> > > be
> > > > > > > handled
> > > > > > > > > in a
> > > > > > > > > > > > > > separate
> > > > > > > > > > > > > > > > jira.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Best,
> > > > > > > > > > > > > > > > > Shengkai
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > [1]
> > > > > > > > > > >
> > > https://www.postgresql.org/docs/current/view-pg-tables.html
> > > > > > > > > > > > > > > > > [2]
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> https://dev.mysql.com/doc/refman/8.4/en/information-schema-tables-table.html
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Gabor Somogyi <gabor.g.somo...@gmail.com>
> > > > > > 于2025年3月3日周一
> > > > > > > > > > > 02:00写道：
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > Hi Zakelly,
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > In order to shoot for simplicity
> `METADATA
> > > > > VIRTUAL`
> > > > > > > as
> > > > > > > > > key
> > > > > > > > > > > > words
> > > > > > > > > > > > > > for
> > > > > > > > > > > > > > > > > > definition is the target.
> > > > > > > > > > > > > > > > > > When it's not super complex the latter
> can
> > be
> > > > > added
> > > > > > > > too.
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > BR,
> > > > > > > > > > > > > > > > > > G
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > On Sun, Mar 2, 2025 at 3:37 PM Zakelly
> Lan
> > <
> > > > > > > > > > > > > zakelly....@gmail.com>
> > > > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > Hi Gabor,
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > +1 for this.
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > Will the metadata column use `METADATA
> > > > VIRTUAL`
> > > > > > as
> > > > > > > > key
> > > > > > > > > > > words
> > > > > > > > > > > > > for
> > > > > > > > > > > > > > > > > > > definition, or `METADATA FROM xxx
> > VIRTUAL`
> > > > for
> > > > > > > > > renaming,
> > > > > > > > > > > just
> > > > > > > > > > > > > > like
> > > > > > > > > > > > > > > > the
> > > > > > > > > > > > > > > > > > > Kafka table?
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > Best,
> > > > > > > > > > > > > > > > > > > Zakelly
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > On Sat, Mar 1, 2025 at 1:31 PM Gabor
> > > Somogyi
> > > > <
> > > > > > > > > > > > > > > > > gabor.g.somo...@gmail.com>
> > > > > > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > Hi All,
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > I'd like to start a discussion of
> > > FLIP-512:
> > > > > Add
> > > > > > > > meta
> > > > > > > > > > > > > > information
> > > > > > > > > > > > > > > to
> > > > > > > > > > > > > > > > > SQL
> > > > > > > > > > > > > > > > > > > > state connector [1].
> > > > > > > > > > > > > > > > > > > > Feel free to add your thoughts to
> make
> > > this
> > > > > > > feature
> > > > > > > > > > > better.
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > [1]
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> https://cwiki.apache.org/confluence/display/FLINK/FLIP-512%3A+Add+meta+information+to+SQL+state+connector
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > BR,
> > > > > > > > > > > > > > > > > > > > G
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > >
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