Hi Timo and Dawid,
It's really great that we have the same goal. I am actually wondering if we
can go one step further to avoid some of the interfaces in Table as well.
For example, if we have the FilterableSource, do we still need the
FilterableTableSource? Should DynamicTableSource just become a Source<*Row*,
SourceSplitT, EnumChkT>?
Can you help me understand a bit more about the reason we need the
following relational representation / wrapper interfaces v.s. the
interfaces that we could put to the Source in FLIP-27?
DynamicTableSource v.s. Source<Row, SourceSplitT, EnumChkT>
SupportsFilterablePushDown v.s. FilterableSource
SupportsProjectablePushDown v.s. ProjectableSource
SupportsWatermarkPushDown v.s. WithWatermarkAssigner
SupportsComputedColumnPushDown v.s. ComputedColumnDeserializer
ScanTableSource v.s. ChangeLogDeserializer.
LookUpTableSource v.s. LookUpSource
Assuming we have all the interfaces on the right side, do we still need the
interfaces on the left side? Note that the interfaces on the right can be
used by both DataStream and Table. If we do this, there will only be one
set of Source interfaces Table and DataStream, the only difference is that
the Source for table will have some specific plugins and configurations. An
omnipotent Source can implement all the the above interfaces and take a
Deserializer that implements both ComputedColumnDeserializer and
ChangeLogDeserializer.
Would the SQL planner work with that?
Thanks,
Jiangjie (Becket) Qin
On Tue, Mar 24, 2020 at 5:03 PM Jingsong Li <jingsongl...@gmail.com> wrote:
> +1. Thanks Timo for the design doc.
>
> We can also consider @Experimental too. But I am +1 to @PublicEvolving, we
> should be confident in the current change.
>
> Best,
> Jingsong Lee
>
> On Tue, Mar 24, 2020 at 4:30 PM Timo Walther <twal...@apache.org> wrote:
>
> > @Becket: We totally agree that we don't need table specific connectors
> > during runtime. As Dawid said, the interfaces proposed here are just for
> > communication with the planner. Once the properties (watermarks,
> > computed column, filters, projecttion etc.) are negotiated, we can
> > configure a regular Flink connector.
> >
> > E.g. setting the watermark assigner and deserialization schema of a
> > Kafka connector.
> >
> > For better separation of concerns, Flink connectors should not include
> > relational interfaces and depend on flink-table. This is the
> > responsibility of table source/sink.
> >
> > @Kurt: I would like to mark them @PublicEvolving already because we need
> > to deprecate the old interfaces as early as possible. We cannot redirect
> > to @Internal interfaces. They are not marked @Public, so we can still
> > evolve them. But a core design shift should not happen again, it would
> > leave a bad impression if we are redesign over and over again. Instead
> > we should be confident in the current change.
> >
> > Regards,
> > Timo
> >
> >
> > On 24.03.20 09:20, Dawid Wysakowicz wrote:
> > > Hi Becket,
> > >
> > > Answering your question, we have the same intention not to duplicate
> > > connectors between datastream and table apis. The interfaces proposed
> in
> > > the FLIP are a way to describe relational properties of a source. The
> > > intention is as you described to translate all of those expressed as
> > > expressions or other Table specific structures into a DataStream
> source.
> > > In other words I think what we are doing here is in line with what you
> > > described.
> > >
> > > Best,
> > >
> > > Dawid
> > >
> > > On 24/03/2020 02:23, Becket Qin wrote:
> > >> Hi Timo,
> > >>
> > >> Thanks for the proposal. I completely agree that the current Table
> > >> connectors could be simplified quite a bit. I haven't finished reading
> > >> everything, but here are some quick thoughts.
> > >>
> > >> Actually to me the biggest question is why should there be two
> different
> > >> connector systems for DataStream and Table? What is the fundamental
> > reason
> > >> that is preventing us from merging them to one?
> > >>
> > >> The basic functionality of a connector is to provide capabilities to
> do
> > IO
> > >> and Serde. Conceptually, Table connectors should just be DataStream
> > >> connectors that are dealing with Rows. It seems that quite a few of
> the
> > >> special connector requirements are just a specific way to do IO /
> Serde.
> > >> Taking SupportsFilterPushDown as an example, imagine we have the
> > following
> > >> interface:
> > >>
> > >> interface FilterableSource<PREDICATE> {
> > >> void applyFilterable(Supplier<PREDICATE> predicate);
> > >> }
> > >>
> > >> And if a ParquetSource would like to support filterable, it will
> become:
> > >>
> > >> class ParquetSource implements Source,
> > FilterableSource(FilterPredicate> {
> > >> ...
> > >> }
> > >>
> > >> For Table, one just need to provide an predicate supplier that
> converts
> > an
> > >> Expression to the specified predicate type. This has a few benefit:
> > >> 1. Same unified API for filterable for sources, regardless of
> > DataStream or
> > >> Table.
> > >> 2. The DataStream users now can also use the ExpressionToPredicate
> > >> supplier if they want to.
> > >>
> > >> To summarize, my main point is that I am wondering if it is possible
> to
> > >> have a single set of connector interface for both Table and
> DataStream,
> > >> rather than having two hierarchies. I am not 100% sure if this would
> > work,
> > >> but if it works, this would be a huge win from both code maintenance
> and
> > >> user experience perspective.
> > >>
> > >> Thanks,
> > >>
> > >> Jiangjie (Becket) Qin
> > >>
> > >>
> > >>
> > >> On Tue, Mar 24, 2020 at 2:03 AM Dawid Wysakowicz <
> > dwysakow...@apache.org>
> > >> wrote:
> > >>
> > >>> Hi Timo,
> > >>>
> > >>> Thank you for the proposal. I think it is an important improvement
> that
> > >>> will benefit many parts of the Table API. The proposal looks really
> > good
> > >>> to me and personally I would be comfortable with voting on the
> current
> > >>> state.
> > >>>
> > >>> Best,
> > >>>
> > >>> Dawid
> > >>>
> > >>> On 23/03/2020 18:53, Timo Walther wrote:
> > >>>> Hi everyone,
> > >>>>
> > >>>> I received some questions around how the new interfaces play
> together
> > >>>> with formats and their factories.
> > >>>>
> > >>>> Furthermore, for MySQL or Postgres CDC logs, the format should be
> able
> > >>>> to return a `ChangelogMode`.
> > >>>>
> > >>>> Also, I incorporated the feedback around the factory design in
> > general.
> > >>>>
> > >>>> I added a new section `Factory Interfaces` to the design document.
> > >>>> This should be helpful to understand the big picture and connecting
> > >>>> the concepts.
> > >>>>
> > >>>> Please let me know what you think?
> > >>>>
> > >>>> Thanks,
> > >>>> Timo
> > >>>>
> > >>>>
> > >>>> On 18.03.20 13:43, Timo Walther wrote:
> > >>>>> Hi Benchao,
> > >>>>>
> > >>>>> this is a very good question. I will update the FLIP about this.
> > >>>>>
> > >>>>> The legacy planner will not support the new interfaces. It will
> only
> > >>>>> support the old interfaces. With the next release, I think the
> Blink
> > >>>>> planner is stable enough to be the default one as well.
> > >>>>>
> > >>>>> Regards,
> > >>>>> Timo
> > >>>>>
> > >>>>> On 18.03.20 08:45, Benchao Li wrote:
> > >>>>>> Hi Timo,
> > >>>>>>
> > >>>>>> Thank you and others for the efforts to prepare this FLIP.
> > >>>>>>
> > >>>>>> The FLIP LGTM generally.
> > >>>>>>
> > >>>>>> +1 for moving blink data structures to table-common, it's useful
> to
> > >>>>>> udf too
> > >>>>>> in the future.
> > >>>>>> A little question is, do we plan to support the new interfaces and
> > data
> > >>>>>> types in legacy planner?
> > >>>>>> Or we only plan to support these new interfaces in blink planner.
> > >>>>>>
> > >>>>>> And using primary keys from DDL instead of derived key information
> > from
> > >>>>>> each query is also a good idea,
> > >>>>>> we met some use cases where this does not works very well before.
> > >>>>>>
> > >>>>>> This FLIP also makes the dependencies of table modules more
> clear, I
> > >>>>>> like
> > >>>>>> it very much.
> > >>>>>>
> > >>>>>> Timo Walther <twal...@apache.org> 于2020年3月17日周二 上午1:36写道：
> > >>>>>>
> > >>>>>>> Hi everyone,
> > >>>>>>>
> > >>>>>>> I'm happy to present the results of long discussions that we had
> > >>>>>>> internally. Jark, Dawid, Aljoscha, Kurt, Jingsong, me, and many
> > more
> > >>>>>>> have contributed to this design document.
> > >>>>>>>
> > >>>>>>> We would like to propose new long-term table source and table
> sink
> > >>>>>>> interfaces:
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>
> >
> https://cwiki.apache.org/confluence/display/FLINK/FLIP-95%3A+New+TableSource+and+TableSink+interfaces
> > >>>>>>>
> > >>>>>>> This is a requirement for FLIP-105 and finalizing FLIP-32.
> > >>>>>>>
> > >>>>>>> The goals of this FLIP are:
> > >>>>>>>
> > >>>>>>> - Simplify the current interface architecture:
> > >>>>>>> - Merge upsert, retract, and append sinks.
> > >>>>>>> - Unify batch and streaming sources.
> > >>>>>>> - Unify batch and streaming sinks.
> > >>>>>>>
> > >>>>>>> - Allow sources to produce a changelog:
> > >>>>>>> - UpsertTableSources have been requested a lot by users.
> Now
> > >>>>>>> is the
> > >>>>>>> time to open the internal planner capabilities via the new
> > interfaces.
> > >>>>>>> - According to FLIP-105, we would like to support
> > changelogs for
> > >>>>>>> processing formats such as Debezium.
> > >>>>>>>
> > >>>>>>> - Don't rely on DataStream API for source and sinks:
> > >>>>>>> - According to FLIP-32, the Table API and SQL should be
> > >>>>>>> independent
> > >>>>>>> of the DataStream API which is why the `table-common` module has
> no
> > >>>>>>> dependencies on `flink-streaming-java`.
> > >>>>>>> - Source and sink implementations should only depend on
> the
> > >>>>>>> `table-common` module after FLIP-27.
> > >>>>>>> - Until FLIP-27 is ready, we still put most of the
> > interfaces in
> > >>>>>>> `table-common` and strictly separate interfaces that communicate
> > >>>>>>> with a
> > >>>>>>> planner and actual runtime reader/writers.
> > >>>>>>>
> > >>>>>>> - Implement efficient sources and sinks without planner
> > dependencies:
> > >>>>>>> - Make Blink's internal data structures available to
> > connectors.
> > >>>>>>> - Introduce stable interfaces for data structures that can
> > be
> > >>>>>>> marked as `@PublicEvolving`.
> > >>>>>>> - Only require dependencies on `flink-table-common` in the
> > >>>>>>> future
> > >>>>>>>
> > >>>>>>> It finalizes the concept of dynamic tables and consideres how all
> > >>>>>>> source/sink related classes play together.
> > >>>>>>>
> > >>>>>>> We look forward to your feedback.
> > >>>>>>>
> > >>>>>>> Regards,
> > >>>>>>> Timo
> > >>>>>>>
> > >>>>>>
> > >>>
> > >
> >
> >
>
> --
> Best, Jingsong Lee
>
