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Re: [DISCUSS] Flink SQL DDL Design

Yeah! I agree with Timo that DDL can actually proceed w/o being blocked by connector API. We can leave the unknown out while defining the basic syntax.


As commented in the doc, I think we can probably stick with simple syntax with general properties, without extending the syntax too much that it mimics the descriptor API. 

Part of our effort on Flink-Hive integration is also to make DDL syntax compatible with Hive's. The one in the current proposal seems making our effort more challenging.

We can help and collaborate. At this moment, I think we can finalize on the proposal and then we can divide the tasks for better collaboration.

Please let me know if there are  any questions or suggestions.


Sender:Timo Walther <twalthr@xxxxxxxxxx>
Sent at:2018 Nov 27 (Tue) 16:21
Recipient:dev <dev@xxxxxxxxxxxxxxxx>
Subject:Re: [DISCUSS] Flink SQL DDL Design

Thanks for offering your help here, Xuefu. It would be great to move 
these efforts forward. I agree that the DDL is somehow releated to the 
unified connector API design but we can also start with the basic 
functionality now and evolve the DDL during this release and next releases.

For example, we could identify the MVP DDL syntax that skips defining 
key constraints and maybe even time attributes. This DDL could be used 
for batch usecases, ETL, and materializing SQL queries (no time 
operations like windows).

The unified connector API is high on our priority list for the 1.8 
release. I will try to update the document until mid of next week.



Am 27.11.18 um 08:08 schrieb Shuyi Chen:
> Thanks a lot, Xuefu. I was busy for some other stuff for the last 2 weeks,
> but we are definitely interested in moving this forward. I think once the
> unified connector API design [1] is done, we can finalize the DDL design as
> well and start creating concrete subtasks to collaborate on the
> implementation with the community.
> Shuyi
> [1]
> On Mon, Nov 26, 2018 at 7:01 PM Zhang, Xuefu <xuefu.z@xxxxxxxxxxxxxxx>
> wrote:
>> Hi Shuyi,
>> I'm wondering if you folks still have the bandwidth working on this.
>> We have some dedicated resource and like to move this forward. We can
>> collaborate.
>> Thanks,
>> Xuefu
>> ------------------------------------------------------------------
>> 发件人:wenlong.lwl<wenlong88.lwl@xxxxxxxxx>
>> 日 期:2018年11月05日 11:15:35
>> 收件人:<dev@xxxxxxxxxxxxxxxx>
>> 主 题:Re: [DISCUSS] Flink SQL DDL Design
>> Hi, Shuyi, thanks for the proposal.
>> I have two concerns about the table ddl:
>> 1. how about remove the source/sink mark from the ddl, because it is not
>> necessary, the framework determine the table referred is a source or a sink
>> according to the context of the query using the table. it will be more
>> convenient for use defining a table which can be both a source and sink,
>> and more convenient for catalog to persistent and manage the meta infos.
>> 2. how about just keeping one pure string map as parameters for table, like
>> create tabe Kafka10SourceTable (
>> intField INTEGER,
>> stringField VARCHAR(128),
>> longField BIGINT,
>> rowTimeField TIMESTAMP
>> ) with (
>> connector.type = ’kafka’,
>> = ’1’,
>> connector.version = ’0.10’,
>> = ‘test-kafka-topic’,
>> = ‘latest-offset’,
>> = ‘offset’,
>> format.type = 'json'
>> format.prperties.version=’1’,
>> format.derive-schema = 'true'
>> );
>> Because:
>> 1. in TableFactory, what user use is a string map properties, defining
>> parameters by string-map can be the closest way to mapping how user use the
>> parameters.
>> 2. The table descriptor can be extended by user, like what is done in Kafka
>> and Json, it means that the parameter keys in connector or format can be
>> different in different implementation, we can not restrict the key in a
>> specified set, so we need a map in connector scope and a map in
>> scope. why not just give user a single map, let them
>> put parameters in a format they like, which is also the simplest way to
>> implement DDL parser.
>> 3. whether we can define a format clause or not, depends on the
>> implementation of the connector, using different clause in DDL may make a
>> misunderstanding that we can combine the connectors with arbitrary formats,
>> which may not work actually.
>> On Sun, 4 Nov 2018 at 18:25, Dominik Wosiński <wossyn@xxxxxxxxx> wrote:
>>> +1, Thanks for the proposal.
>>> I guess this is a long-awaited change. This can vastly increase the
>>> functionalities of the SQL Client as it will be possible to use complex
>>> extensions like for example those provided by Apache Bahir[1].
>>> Best Regards,
>>> Dom.
>>> [1]
>>> sob., 3 lis 2018 o 17:17 Rong Rong <walterddr@xxxxxxxxx> napisał(a):
>>>> +1. Thanks for putting the proposal together Shuyi.
>>>> DDL has been brought up in a couple of times previously [1,2].
>> Utilizing
>>>> DDL will definitely be a great extension to the current Flink SQL to
>>>> systematically support some of the previously brought up features such
>> as
>>>> [3]. And it will also be beneficial to see the document closely aligned
>>>> with the previous discussion for unified SQL connector API [4].
>>>> I also left a few comments on the doc. Looking forward to the alignment
>>>> with the other couple of efforts and contributing to them!
>>>> Best,
>>>> Rong
>>>> [1]
>>>> [2]
>>>> [3]
>>>> [4]
>>>> On Fri, Nov 2, 2018 at 10:22 AM Bowen Li <bowenli86@xxxxxxxxx> wrote:
>>>>> Thanks Shuyi!
>>>>> I left some comments there. I think the design of SQL DDL and
>>> Flink-Hive
>>>>> integration/External catalog enhancements will work closely with each
>>>>> other. Hope we are well aligned on the directions of the two designs,
>>>> and I
>>>>> look forward to working with you guys on both!
>>>>> Bowen
>>>>> On Thu, Nov 1, 2018 at 10:57 PM Shuyi Chen <suez1224@xxxxxxxxx>
>> wrote:
>>>>>> Hi everyone,
>>>>>> SQL DDL support has been a long-time ask from the community.
>> Current
>>>>> Flink
>>>>>> SQL support only DML (e.g. SELECT and INSERT statements). In its
>>>> current
>>>>>> form, Flink SQL users still need to define/create table sources and
>>>> sinks
>>>>>> programmatically in Java/Scala. Also, in SQL Client, without DDL
>>>> support,
>>>>>> the current implementation does not allow dynamical creation of
>>> table,
>>>>> type
>>>>>> or functions with SQL, this adds friction for its adoption.
>>>>>> I drafted a design doc [1] with a few other community members that
>>>>> proposes
>>>>>> the design and implementation for adding DDL support in Flink. The
>>>>> initial
>>>>>> design considers DDL for table, view, type, library and function.
>> It
>>>> will
>>>>>> be great to get feedback on the design from the community, and
>> align
>>>> with
>>>>>> latest effort in unified SQL connector API [2] and Flink Hive
>>>>> integration
>>>>>> [3].
>>>>>> Any feedback is highly appreciated.
>>>>>> Thanks
>>>>>> Shuyi Chen
>>>>>> [1]
>>>>>> [2]
>>>>>> [3]
>>>>>> --
>>>>>> "So you have to trust that the dots will somehow connect in your
>>>> future."