Hi Timo, Great thanks for your feedback. I would like to share my thoughts with you inline. :)
Best, Jincheng Timo Walther <twal...@apache.org> 于2019年9月2日周一 下午5:04写道： > Hi all, > > the FLIP looks awesome. However, I would like to discuss the changes to > the user-facing parts again. Some feedback: > > 1. DataViews: With the current non-annotation design for DataViews, we > cannot perform eager state declaration, right? At which point during > execution do we know which state is required by the function? We need to > instantiate the function first, right? > >> We will analysis the Python AggregateFunction and extract the DataViews used in the Python AggregateFunction. This can be done by instantiate a Python AggregateFunction, creating an accumulator by calling method create_accumulator and then analysis the created accumulator. This is actually similar to the way that Java AggregateFunction processing codegen logic. The extracted DataViews can then be used to construct the StateDescriptors in the operator, i.e., we should have hold the state spec and the state descriptor id in Java operator and Python worker can access the state by specifying the corresponding state descriptor id. > 2. Serializability of functions: How do we ensure serializability of > functions for catalog persistence? In the Scala/Java API, we would like > to register classes instead of instances soon. This is the only way to > store a function properly in a catalog or we need some > serialization/deserialization logic in the function interfaces to > convert an instance to string properties. > >> The Python function will be serialized with CloudPickle anyway in the Python API as we need to transfer it to the Python worker which can then deserialize it for execution. The serialized Python function can be stored into catalog. > 3. TableEnvironment: What is the signature of `register_function(self, > name, function)`? Does it accept both a class and function? Like `class > Sum` and `def split()`? Could you add some examples for registering both > kinds of functions? > >> It has been already supported which you mentioned. You can find an example in the POC code: https://github.com/dianfu/flink/commit/93f41ba173482226af7513fdec5acba72b274489#diff-34f619b31a7e38604e22a42a441fbe2fR26 > 4. FunctionDefinition: Function definition is not a user-defined > function definition. It is the highest interface for both user-defined > and built-in functions. I'm not sure if getLanguage() should be part of > this interface or one-level down which would be `UserDefinedFunction`. > Built-in functions will never be implemented in a different language. In > any case, I would vote for removing the UNKNOWN language, because it > does not solve anything. Why should a user declare a function that the > runtime can not handle? I also find the term `JAVA` confusing for Scala > users. How about `FunctionLanguage.JVM` instead? > >> Actually we may have built-in Python functions in the future. Regarding to the following expression: py_udf1(a, b) + py_udf2(c), if there is built-in Python funciton for '+' operator, then we don't need to mix using Java and Python UDFs. In this way, we can improve the execution performance. Regarding to removing FunctionLanguage.UNKNOWN and renaming FunctionLanguage.Java to FunctionLanguage.JVM, it makes more sense to me. > 5. Function characteristics: In the current design, function classes do > not extend from any upper class. How can users declare characteristics > that are present in `FunctionDefinition` like determinism, requirements, > or soon also monotonism. > >> Actually we have defined 'UserDefinedFunction' which is the base class for all user-defined functions. We can define the deterministic, requirements, etc in this class. Currently, we have already supported to define the deterministic. > > Thanks, > Timo > > > On 02.09.19 03:38, Shaoxuan Wang wrote: > > Hi Jincheng, Fudian, and Aljoscha, > > I am assuming the proposed python UDX can also be applied to Flink SQL. > > Is this correct? If yes, I would suggest to title the FLIP as "Flink > Python > > User-Defined Function" or "Flink Python User-Defined Function for Table". > > > > Regards, > > Shaoxuan > > > > > > On Wed, Aug 28, 2019 at 12:22 PM jincheng sun <sunjincheng...@gmail.com> > > wrote: > > > >> Thanks for the feedback Bowen! > >> > >> Great thanks for create the FLIP and bring up the VOTE Dian! > >> > >> Best, Jincheng > >> > >> Dian Fu <dian0511...@gmail.com> 于2019年8月28日周三 上午11:32写道： > >> > >>> Hi all, > >>> > >>> I have started a voting thread [1]. Thanks a lot for your help during > >>> creating the FLIP @Jincheng. > >>> > >>> > >>> Hi Bowen, > >>> > >>> Very appreciated for your comments. I have replied you in the design > doc. > >>> As it seems that the comments doesn't affect the overall design, I'll > not > >>> cancel the vote for now and we can continue the discussion in the > design > >>> doc. > >>> > >>> [1] > >>> > >> > http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/VOTE-FLIP-58-Flink-Python-User-Defined-Function-for-Table-API-td32295.html > >>> < > >>> > >> > http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/VOTE-FLIP-58-Flink-Python-User-Defined-Function-for-Table-API-td32295.html > >>> Regards, > >>> Dian > >>> > >>>> 在 2019年8月28日，上午11:05，Bowen Li <bowenl...@gmail.com> 写道： > >>>> > >>>> Hi Jincheng and Dian, > >>>> > >>>> Sorry for being late to the party. I took a glance at the proposal, > >> LGTM > >>> in > >>>> general, and I left only a couple comments. > >>>> > >>>> Thanks, > >>>> Bowen > >>>> > >>>> > >>>> On Mon, Aug 26, 2019 at 8:05 PM Dian Fu <dian0511...@gmail.com> > wrote: > >>>> > >>>>> Hi Jincheng, > >>>>> > >>>>> Thanks! It works. > >>>>> > >>>>> Thanks, > >>>>> Dian > >>>>> > >>>>>> 在 2019年8月27日，上午10:55，jincheng sun <sunjincheng...@gmail.com> 写道： > >>>>>> > >>>>>> Hi Dian, can you check if you have edit access? :) > >>>>>> > >>>>>> > >>>>>> Dian Fu <dian0511...@gmail.com> 于2019年8月26日周一 上午10:52写道： > >>>>>> > >>>>>>> Hi Jincheng, > >>>>>>> > >>>>>>> Appreciated for the kind tips and offering of help. Definitely need > >>> it! > >>>>>>> Could you grant me write permission for confluence? My Id: Dian Fu > >>>>>>> > >>>>>>> Thanks, > >>>>>>> Dian > >>>>>>> > >>>>>>>> 在 2019年8月26日，上午9:53，jincheng sun <sunjincheng...@gmail.com> 写道： > >>>>>>>> > >>>>>>>> Thanks for your feedback Hequn & Dian. > >>>>>>>> > >>>>>>>> Dian, I am glad to see that you want help to create the FLIP! > >>>>>>>> Everyone will have first time, and I am very willing to help you > >>>>> complete > >>>>>>>> your first FLIP creation. Here some tips: > >>>>>>>> > >>>>>>>> - First I'll give your account write permission for confluence. > >>>>>>>> - Before create the FLIP, please have look at the FLIP Template > >> [1], > >>>>>>> (It's > >>>>>>>> better to know more about FLIP by reading [2]) > >>>>>>>> - Create Flink Python UDFs related JIRAs after completing the VOTE > >> of > >>>>>>>> FLIP.(I think you also can bring up the VOTE thread, if you want! > ) > >>>>>>>> > >>>>>>>> Any problems you encounter during this period，feel free to tell me > >>> that > >>>>>>> we > >>>>>>>> can solve them together. :) > >>>>>>>> > >>>>>>>> Best, > >>>>>>>> Jincheng > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> > >>>>>>>> [1] > >> https://cwiki.apache.org/confluence/display/FLINK/FLIP+Template > >>>>>>>> [2] > >>>>>>>> > >> > https://cwiki.apache.org/confluence/display/FLINK/Flink+Improvement+Proposals > >>>>>>>> > >>>>>>>> Hequn Cheng <chenghe...@gmail.com> 于2019年8月23日周五 上午11:54写道： > >>>>>>>> > >>>>>>>>> +1 for starting the vote. > >>>>>>>>> > >>>>>>>>> Thanks Jincheng a lot for the discussion. > >>>>>>>>> > >>>>>>>>> Best, Hequn > >>>>>>>>> > >>>>>>>>> On Fri, Aug 23, 2019 at 10:06 AM Dian Fu <dian0511...@gmail.com> > >>>>> wrote: > >>>>>>>>>> Hi Jincheng, > >>>>>>>>>> > >>>>>>>>>> +1 to start the FLIP create and VOTE on this feature. I'm > willing > >>> to > >>>>>>> help > >>>>>>>>>> on the FLIP create if you don't mind. As I haven't created a > FLIP > >>>>>>> before, > >>>>>>>>>> it will be great if you could help on this. :) > >>>>>>>>>> > >>>>>>>>>> Regards, > >>>>>>>>>> Dian > >>>>>>>>>> > >>>>>>>>>>> 在 2019年8月22日，下午11:41，jincheng sun <sunjincheng...@gmail.com> > >> 写道： > >>>>>>>>>>> Hi all, > >>>>>>>>>>> > >>>>>>>>>>> Thanks a lot for your feedback. If there are no more > suggestions > >>> and > >>>>>>>>>>> comments, I think it's better to initiate a vote to create a > >> FLIP > >>>>> for > >>>>>>>>>>> Apache Flink Python UDFs. > >>>>>>>>>>> What do you think? > >>>>>>>>>>> > >>>>>>>>>>> Best, Jincheng > >>>>>>>>>>> > >>>>>>>>>>> jincheng sun <sunjincheng...@gmail.com> 于2019年8月15日周四 > >> 上午12:54写道： > >>>>>>>>>>>> Hi Thomas, > >>>>>>>>>>>> > >>>>>>>>>>>> Thanks for your confirmation and the very important reminder > >>> about > >>>>>>>>>> bundle > >>>>>>>>>>>> processing. > >>>>>>>>>>>> > >>>>>>>>>>>> I have had add the description about how to perform bundle > >>>>> processing > >>>>>>>>>> from > >>>>>>>>>>>> the perspective of checkpoint and watermark. Feel free to > leave > >>>>>>>>>> comments if > >>>>>>>>>>>> there are anything not describe clearly. > >>>>>>>>>>>> > >>>>>>>>>>>> Best, > >>>>>>>>>>>> Jincheng > >>>>>>>>>>>> > >>>>>>>>>>>> > >>>>>>>>>>>> Dian Fu <dian0511...@gmail.com> 于2019年8月14日周三 上午10:08写道： > >>>>>>>>>>>> > >>>>>>>>>>>>> Hi Thomas, > >>>>>>>>>>>>> > >>>>>>>>>>>>> Thanks a lot the suggestions. > >>>>>>>>>>>>> > >>>>>>>>>>>>> Regarding to bundle processing, there is a section > >>> "Checkpoint"[1] > >>>>>>> in > >>>>>>>>>> the > >>>>>>>>>>>>> design doc which talks about how to handle the checkpoint. > >>>>>>>>>>>>> However, I think you are right that we should talk more about > >>> it, > >>>>>>>>> such > >>>>>>>>>> as > >>>>>>>>>>>>> what's bundle processing, how it affects the checkpoint and > >>>>>>>>> watermark, > >>>>>>>>>> how > >>>>>>>>>>>>> to handle the checkpoint and watermark, etc. > >>>>>>>>>>>>> > >>>>>>>>>>>>> [1] > >>>>>>>>>>>>> > >> > https://docs.google.com/document/d/1WpTyCXAQh8Jr2yWfz7MWCD2-lou05QaQFb810ZvTefY/edit#heading=h.urladt565yo3 > >>>>>>>>>>>>> < > >>>>>>>>>>>>> > >> > https://docs.google.com/document/d/1WpTyCXAQh8Jr2yWfz7MWCD2-lou05QaQFb810ZvTefY/edit#heading=h.urladt565yo3 > >>>>>>>>>>>>> Regards, > >>>>>>>>>>>>> Dian > >>>>>>>>>>>>> > >>>>>>>>>>>>>> 在 2019年8月14日，上午1:01，Thomas Weise <t...@apache.org> 写道： > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> Hi Jincheng, > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> Thanks for putting this together. The proposal is very > >>> detailed, > >>>>>>>>>>>>> thorough > >>>>>>>>>>>>>> and for me as a Beam Flink runner contributor easy to > >>> understand > >>>>> :) > >>>>>>>>>>>>>> One thing that you should probably detail more is the bundle > >>>>>>>>>>>>> processing. It > >>>>>>>>>>>>>> is critically important for performance that multiple > >> elements > >>>>> are > >>>>>>>>>>>>>> processed in a bundle. The default bundle size in the Flink > >>>>> runner > >>>>>>>>> is > >>>>>>>>>>>>> 1s or > >>>>>>>>>>>>>> 1000 elements, whichever comes first. And for streaming, you > >>> can > >>>>>>>>> find > >>>>>>>>>>>>> the > >>>>>>>>>>>>>> logic necessary to align the bundle processing with > >> watermarks > >>>>> and > >>>>>>>>>>>>>> checkpointing here: > >>>>>>>>>>>>>> > >> > https://github.com/apache/beam/blob/release-2.14.0/runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/ExecutableStageDoFnOperator.java > >>>>>>>>>>>>>> Thomas > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> > >>>>>>>>>>>>>> On Tue, Aug 13, 2019 at 7:05 AM jincheng sun < > >>>>>>>>>> sunjincheng...@gmail.com> > >>>>>>>>>>>>>> wrote: > >>>>>>>>>>>>>> > >>>>>>>>>>>>>>> Hi all, > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> The Python Table API(without Python UDF support) has > already > >>>>> been > >>>>>>>>>>>>> supported > >>>>>>>>>>>>>>> and will be available in the coming release 1.9. > >>>>>>>>>>>>>>> As Python UDF is very important for Python users, we'd like > >> to > >>>>>>>>> start > >>>>>>>>>>>>> the > >>>>>>>>>>>>>>> discussion about the Python UDF support in the Python Table > >>> API. > >>>>>>>>>>>>>>> Aljoscha Krettek, Dian Fu and I have discussed offline and > >>> have > >>>>>>>>>>>>> drafted a > >>>>>>>>>>>>>>> design doc[1]. It includes the following items: > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> - The user-defined function interfaces. > >>>>>>>>>>>>>>> - The user-defined function execution architecture. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> As mentioned by many guys in the previous discussion > >>> thread[2], > >>>>> a > >>>>>>>>>>>>>>> portability framework was introduced in Apache Beam in > >> latest > >>>>>>>>>>>>> releases. It > >>>>>>>>>>>>>>> provides well-defined, language-neutral data structures and > >>>>>>>>> protocols > >>>>>>>>>>>>> for > >>>>>>>>>>>>>>> language-neutral user-defined function execution. This > >> design > >>> is > >>>>>>>>>> based > >>>>>>>>>>>>> on > >>>>>>>>>>>>>>> Beam's portability framework. We will introduce how to make > >>> use > >>>>> of > >>>>>>>>>>>>> Beam's > >>>>>>>>>>>>>>> portability framework for user-defined function execution: > >>> data > >>>>>>>>>>>>>>> transmission, state access, checkpoint, metrics, logging, > >> etc. > >>>>>>>>>>>>>>> Considering that the design relies on Beam's portability > >>>>> framework > >>>>>>>>>> for > >>>>>>>>>>>>>>> Python user-defined function execution and not all the > >>>>>>> contributors > >>>>>>>>>> in > >>>>>>>>>>>>>>> Flink community are familiar with Beam's portability > >>> framework, > >>>>> we > >>>>>>>>>> have > >>>>>>>>>>>>>>> done a prototype[3] for proof of concept and also ease of > >>>>>>>>>>>>> understanding of > >>>>>>>>>>>>>>> the design. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> Welcome any feedback. > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> Best, > >>>>>>>>>>>>>>> Jincheng > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> [1] > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >> > https://docs.google.com/document/d/1WpTyCXAQh8Jr2yWfz7MWCD2-lou05QaQFb810ZvTefY/edit?usp=sharing > >>>>>>>>>>>>>>> [2] > >>>>>>>>>>>>>>> > >>>>>>>>>>>>>>> > >> > http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/DISCUSS-FLIP-38-Support-python-language-in-flink-TableAPI-td28061.html > >>>>>>>>>>>>>>> [3] https://github.com/dianfu/flink/commits/udf_poc > >>>>>>>>>>>>>>> > >>>>>>>>>>>>> > >>>>>>>>>> > >>>>>>> > >>>>> > >>> > >
