I agree with Jingsong that sink schema inference and system tables can be
considered later. I wouldn’t recommend to tackle them for the sake of
simplifying user experience to the extreme. Providing the above handy
source and sink implementations already offer users a ton of immediate
value.
On Mon, Mar 23, 2020 at 20:20 Jingsong Li <jingsongl...@gmail.com> wrote:
> Hi Benchao,
>
> > do you think we need to add more columns with various types?
>
> I didn't list all types, but we should support primitive types, varchar,
> Decimal, Timestamp and etc...
> This can be done continuously.
>
> Hi Benchao, Jark,
> About console and blackhole, yes, they can have no schema, the schema can
> be inferred by upstream node.
> - But now we don't have this mechanism to do these configurable sink
> things.
> - If we want to support, we need a single way to support these two sinks.
> - And uses can use "create table like" and others way to simplify DDL.
>
> And for providing system/registered tables (`console` and `blackhole`):
> - I have no strong opinion on these system tables. In SQL, will be "insert
> into blackhole select a /*int*/, b /*string*/ from tableA", "insert into
> blackhole select a /*double*/, b /*Map*/, c /*string*/ from tableB". It
> seems that Blackhole is a universal thing, which makes me feel bad
> intuitively.
> - Can user override these tables? If can, we need ensure it can be
> overwrite by catalog tables.
>
> So I think we can leave these system tables to future too.
> What do you think?
>
> Best,
> Jingsong Lee
>
> On Mon, Mar 23, 2020 at 4:44 PM Jark Wu <imj...@gmail.com> wrote:
>
> > Hi Jingsong,
> >
> > Regarding (2) and (3), I was thinking to ignore manually DDL work, so
> users
> > can use them directly:
> >
> > # this will log results to `.out` files
> > INSERT INTO console
> > SELECT ...
> >
> > # this will drop all received records
> > INSERT INTO blackhole
> > SELECT ...
> >
> > Here `console` and `blackhole` are system sinks which is similar to
> system
> > functions.
> >
> > Best,
> > Jark
> >
> > On Mon, 23 Mar 2020 at 16:33, Benchao Li <libenc...@gmail.com> wrote:
> >
> > > Hi Jingsong,
> > >
> > > Thanks for bring this up. Generally, it's a very good proposal.
> > >
> > > About data gen source, do you think we need to add more columns with
> > > various types?
> > >
> > > About print sink, do we need to specify the schema?
> > >
> > > Jingsong Li <jingsongl...@gmail.com> 于2020年3月23日周一 下午1:51写道：
> > >
> > > > Thanks Bowen, Jark and Dian for your feedback and suggestions.
> > > >
> > > > I reorganize with your suggestions, and try to expose DDLs:
> > > >
> > > > 1.datagen source:
> > > > - easy startup/test for streaming job
> > > > - performance testing
> > > >
> > > > DDL:
> > > > CREATE TABLE user (
> > > > id BIGINT,
> > > > age INT,
> > > > description STRING
> > > > ) WITH (
> > > > 'connector.type' = 'datagen',
> > > > 'connector.rows-per-second'='100',
> > > > 'connector.total-records'='1000000',
> > > >
> > > > 'schema.id.generator' = 'sequence',
> > > > 'schema.id.generator.start' = '1',
> > > >
> > > > 'schema.age.generator' = 'random',
> > > > 'schema.age.generator.min' = '0',
> > > > 'schema.age.generator.max' = '100',
> > > >
> > > > 'schema.description.generator' = 'random',
> > > > 'schema.description.generator.length' = '100'
> > > > )
> > > >
> > > > Default is random generator.
> > > > Hi Jark, I don't want to bring complicated regularities, because it
> can
> > > be
> > > > done through computed columns. And it is hard to define
> > > > standard regularities, I think we can leave it to the future.
> > > >
> > > > 2.print sink:
> > > > - easy test for streaming job
> > > > - be very useful in production debugging
> > > >
> > > > DDL:
> > > > CREATE TABLE print_table (
> > > > ...
> > > > ) WITH (
> > > > 'connector.type' = 'print'
> > > > )
> > > >
> > > > 3.blackhole sink
> > > > - very useful for high performance testing of Flink
> > > > - I've also run into users trying UDF to output, not sink, so they
> need
> > > > this sink as well.
> > > >
> > > > DDL:
> > > > CREATE TABLE blackhole_table (
> > > > ...
> > > > ) WITH (
> > > > 'connector.type' = 'blackhole'
> > > > )
> > > >
> > > > What do you think?
> > > >
> > > > Best,
> > > > Jingsong Lee
> > > >
> > > > On Mon, Mar 23, 2020 at 12:04 PM Dian Fu <dian0511...@gmail.com>
> > wrote:
> > > >
> > > > > Thanks Jingsong for bringing up this discussion. +1 to this
> > proposal. I
> > > > > think Bowen's proposal makes much sense to me.
> > > > >
> > > > > This is also a painful problem for PyFlink users. Currently there
> is
> > no
> > > > > built-in easy-to-use table source/sink and it requires users to
> > write a
> > > > lot
> > > > > of code to trying out PyFlink. This is especially painful for new
> > users
> > > > who
> > > > > are not familiar with PyFlink/Flink. I have also encountered the
> > > tedious
> > > > > process Bowen encountered, e.g. writing random source connector,
> > print
> > > > sink
> > > > > and also blackhole print sink as there are no built-in ones to use.
> > > > >
> > > > > Regards,
> > > > > Dian
> > > > >
> > > > > > 在 2020年3月22日，上午11:24，Jark Wu <imj...@gmail.com> 写道：
> > > > > >
> > > > > > +1 to Bowen's proposal. I also saw many requirements on such
> > built-in
> > > > > > connectors.
> > > > > >
> > > > > > I will leave some my thoughts here:
> > > > > >
> > > > > >> 1. datagen source (random source)
> > > > > > I think we can merge the functinality of sequence-source into
> > random
> > > > > source
> > > > > > to allow users to custom their data values.
> > > > > > Flink can generate random data according to the field types,
> users
> > > > > > can customize their values to be more domain specific, e.g.
> > > > > > 'field.user'='User_[1-9]{0,1}'
> > > > > > This will be similar to kafka-datagen-connect[1].
> > > > > >
> > > > > >> 2. console sink (print sink)
> > > > > > This will be very useful in production debugging, to easily
> output
> > an
> > > > > > intermediate view or result view to a `.out` file.
> > > > > > So that we can look into the data representation, or check dirty
> > > data.
> > > > > > This should be out-of-box without manually DDL registration.
> > > > > >
> > > > > >> 3. blackhole sink (no output sink)
> > > > > > This is very useful for high performance testing of Flink, to
> > > meansure
> > > > > the
> > > > > > throughput of the whole pipeline without sink.
> > > > > > Presto also provides this as a built-in connector [2].
> > > > > >
> > > > > > Best,
> > > > > > Jark
> > > > > >
> > > > > > [1]:
> > > > > >
> > > > >
> > > >
> > >
> >
> https://github.com/confluentinc/kafka-connect-datagen#define-a-new-schema-specification
> > > > > > [2]: https://prestodb.io/docs/current/connector/blackhole.html
> > > > > >
> > > > > >
> > > > > > On Sat, 21 Mar 2020 at 12:31, Bowen Li <bowenl...@gmail.com>
> > wrote:
> > > > > >
> > > > > >> +1.
> > > > > >>
> > > > > >> I would suggest to take a step even further and see what users
> > > really
> > > > > need
> > > > > >> to test/try/play with table API and Flink SQL. Besides this one,
> > > > here're
> > > > > >> some more sources and sinks that I have developed or used
> > previously
> > > > to
> > > > > >> facilitate building Flink table/SQL pipelines.
> > > > > >>
> > > > > >>
> > > > > >> 1. random input data source
> > > > > >> - should generate random data at a specified rate according
> > to
> > > > > schema
> > > > > >> - purposes
> > > > > >> - test Flink pipeline and data can end up in external
> > > storage
> > > > > >> correctly
> > > > > >> - stress test Flink sink as well as tuning up external
> > > storage
> > > > > >> 2. print data sink
> > > > > >> - should print data in row format in console
> > > > > >> - purposes
> > > > > >> - make it easier to test Flink SQL job e2e in IDE
> > > > > >> - test Flink pipeline and ensure output data
> format/value
> > is
> > > > > >> correct
> > > > > >> 3. no output data sink
> > > > > >> - just swallow output data without doing anything
> > > > > >> - purpose
> > > > > >> - evaluate and tune performance of Flink source and the
> > > whole
> > > > > >> pipeline. Users' don't need to worry about sink back
> > > pressure
> > > > > >>
> > > > > >> These may be taken into consideration all together as an effort
> to
> > > > lower
> > > > > >> the threshold of running Flink SQL/table API, and facilitate
> > users'
> > > > > daily
> > > > > >> work.
> > > > > >>
> > > > > >> Cheers,
> > > > > >> Bowen
> > > > > >>
> > > > > >>
> > > > > >> On Thu, Mar 19, 2020 at 10:32 PM Jingsong Li <
> > > jingsongl...@gmail.com>
> > > > > >> wrote:
> > > > > >>
> > > > > >>> Hi all,
> > > > > >>>
> > > > > >>> I heard some users complain that table is difficult to test.
> Now
> > > with
> > > > > SQL
> > > > > >>> client, users are more and more inclined to use it to test
> rather
> > > > than
> > > > > >>> program.
> > > > > >>> The most common example is Kafka source. If users need to test
> > > their
> > > > > SQL
> > > > > >>> output and checkpoint, they need to:
> > > > > >>>
> > > > > >>> - 1.Launch a Kafka standalone, create a Kafka topic .
> > > > > >>> - 2.Write a program, mock input records, and produce records to
> > > Kafka
> > > > > >>> topic.
> > > > > >>> - 3.Then test in Flink.
> > > > > >>>
> > > > > >>> The step 1 and 2 are annoying, although this test is E2E.
> > > > > >>>
> > > > > >>> Then I found StatefulSequenceSource, it is very good because it
> > has
> > > > > deal
> > > > > >>> with checkpoint things, so it is very good to checkpoint
> > > > > >> mechanism.Usually,
> > > > > >>> users are turned on checkpoint in production.
> > > > > >>>
> > > > > >>> With computed columns, user are easy to create a sequence
> source
> > > DDL
> > > > > same
> > > > > >>> to Kafka DDL. Then they can test inside Flink, don't need
> launch
> > > > other
> > > > > >>> things.
> > > > > >>>
> > > > > >>> Have you consider this? What do you think?
> > > > > >>>
> > > > > >>> CC: @Aljoscha Krettek <aljos...@apache.org> the author
> > > > > >>> of StatefulSequenceSource.
> > > > > >>>
> > > > > >>> Best,
> > > > > >>> Jingsong Lee
> > > > > >>>
> > > > > >>
> > > > >
> > > > >
> > > >
> > > > --
> > > > Best, Jingsong Lee
> > > >
> > >
> > >
> > > --
> > >
> > > Benchao Li
> > > School of Electronics Engineering and Computer Science, Peking
> University
> > > Tel:+86-15650713730
> > > Email: libenc...@gmail.com; libenc...@pku.edu.cn
> > >
> >
>
>
> --
> Best, Jingsong Lee
>
