Fine by me. Thanks for driving this Lincoln :) Best, Piotrek
wt., 20 wrz 2022 o 09:06 Lincoln Lee <lincoln.8...@gmail.com> napisał(a): > Hi all, > I'll start a vote if there are no more objections till this > thursday(9.22). Looking forward to your feedback! > > [1] Flip-260: > > https://cwiki.apache.org/confluence/display/FLINK/FLIP-260%3A+Expose+Finish+Method+For+TableFunction > [2] PoC: https://github.com/lincoln-lil/flink/tree/tf-finish-poc > > Best, > Lincoln Lee > > > Lincoln Lee <lincoln.8...@gmail.com> 于2022年9月19日周一 17:38写道： > > > Hi Jingsong, > > Thank you for participating this discussion! For the method name, I > > think we should follow the new finish() method in `StreamOperator`, the > > BoundedOneInput might be removed in the future as discussed [1] before > > > > [1] https://lists.apache.org/thread/3ozw653ql8jso9w55p4pw8p4909trvkb > > > > Best, > > Lincoln Lee > > > > > > Jingsong Li <jingsongl...@gmail.com> 于2022年9月19日周一 10:13写道： > > > >> +1 to add `finish()` method to `TableFunction` only. > >> > >> Can we use `endInput` just like `BoundedOneInput`? > >> > >> Best, > >> Jingsong > >> > >> On Fri, Sep 16, 2022 at 11:54 PM Lincoln Lee <lincoln.8...@gmail.com> > >> wrote: > >> > > >> > Hi Dawid, Piotr, > >> > Agree with you that add finish() method to `TableFunction` only. > >> Other > >> > `UserDefinedFunction`s (`ScalarFunction`, `AggregateFunction`, > >> > `AggregateTableFunction`) are not necessarily to have the finish > >> > method(they can not emit records in legacy close() method). > >> > > >> > A `TableFunction` is used to correlate with the left table/stream, the > >> > following example shows a case that user only select columns from the > >> > correlated 'FeatureTF' (no left table column was selected): > >> > ``` > >> > SELECT feature1, feature2, feature3 > >> > FROM MyTable t1 > >> > JOIN LATERAL TABLE(FeatureTF(t1.f0, t1.f1)) AS F(feature1, feature2, > >> > feature3) ON TRUE > >> > ``` > >> > the 'FeatureTF' can do some flushing work in legacy close() method and > >> this > >> > doesn't break any sql semantics, so I don't see any reason that we can > >> > enforce users not do flushing work in new finish() method. I've > updated > >> the > >> > flip doc to limit the change only for `TableFunction`[1]. > >> > > >> > For the more powerful `ProcessFunction`, I'd like to share some > >> thoughts: > >> > There indeed exists requirements for advanced usage in Table/SQL, > even a > >> > further UD-Operator, e.g., UD-Join for user controlled join logic > which > >> can > >> > not simply expressed by SQL. This is an interesting topic, expect more > >> > discussions on this. > >> > > >> > > >> > [1] > >> > > >> > https://cwiki.apache.org/confluence/display/FLINK/FLIP-260%3A+Expose+Finish+Method+For+TableFunction > >> > > >> > Best, > >> > Lincoln Lee > >> > > >> > > >> > Piotr Nowojski <pnowoj...@apache.org> 于2022年9月15日周四 22:39写道： > >> > > >> > > Hi Dawid, Lincoln, > >> > > > >> > > I would tend to agree with Dawid. It seems to me like > `TableFunction` > >> is > >> > > the one that needs to be taken care of. Other types of > >> > > `UserDefinedFunction` wouldn't be able to emit anything from the > >> `finish()` > >> > > even if we added it. And if we added `finish(Collector<T> out)` to > >> them, it > >> > > would create the same problems (how to pass the output type) that > >> prevented > >> > > us from adding `finish()` to all functions in the DataStream API. > >> > > > >> > > However I'm not sure what should be the long term solution for the > >> Table > >> > > API. For the DataStream API we wanted to provide a new, better and > >> more > >> > > powerful `ProcessFunction` for all of the unusual use cases, that > >> currently > >> > > require the use of `StreamOperator` API instead of `DataStream` > >> functions. > >> > > I don't know what would be an alternative in the Table API. > >> > > > >> > > Dawid, who do you think we should ping from the Table API/SQL teams > >> to chip > >> > > in? > >> > > > >> > > Best, > >> > > Piotrek > >> > > > >> > > czw., 15 wrz 2022 o 12:38 Dawid Wysakowicz <dwysakow...@apache.org> > >> > > napisał(a): > >> > > > >> > > > Hey Lincoln, > >> > > > > >> > > > Thanks for opening the discussion. > >> > > > > >> > > > To be honest I am not convinced if emitting from close there is a > >> > > > contract that was envisioned and thus should be maintained. As far > >> as I > >> > > > can see it does affect only the TableFunction, because it has the > >> > > > collect method. None of the other UDFs (ScalarFunction, > >> > > > AggregateFunction) have means to emit records from close(). > >> > > > > >> > > > To be honest I am not sure what would be the consequences of > >> interplay > >> > > > with other operators which expect TableFunction to emit only when > >> eval > >> > > > is called. Not sure if there are such. > >> > > > > >> > > > If it is a thing that we are certain we want to support, I'd be > much > >> > > > more comfortable adding finish() to the TableFunction instead. > >> Would be > >> > > > happy to hear opinions from the Table API folks. > >> > > > > >> > > > Best, > >> > > > > >> > > > Dawid > >> > > > > >> > > > On 14/09/2022 15:55, Lincoln Lee wrote: > >> > > > > Thanks @Piort for your valuable inputs! > >> > > > > > >> > > > > I did a quick read of the previous discussion you mentioned, > >> seems my > >> > > > flip > >> > > > > title doesn't give a clear scope here and make some confusions, > >> if my > >> > > > > understanding is correct, the UDFs in your context is the user > >> > > > > implemented `org.apache.flink.api.common.functions.Function`s, > >> while > >> > > the > >> > > > > `UserDefinedFunction` I mentioned in the flip is limited to the > >> > > > flink-table > >> > > > > module which located in `org.apache.flink.table.functions`. > >> > > > > > >> > > > > Here's an use case we've met recently (which is indeed the > >> motivation > >> > > to > >> > > > > propose this): > >> > > > > one of our user implemented a > >> > > > > `org.apache.flink.table.functions.TableFunction`, the simplified > >> > > > > pseudo-code is as below: > >> > > > > > >> > > > > ``` > >> > > > > class XFunction extend TableFunction<Out> { > >> > > > > > >> > > > > open(FunctionContext context){ > >> > > > > initMemQueue(); > >> > > > > initPythonProc() > >> > > > > } > >> > > > > > >> > > > > eval(In in){ > >> > > > > queue.offer(data) > >> > > > > Out out = queue.poll() > >> > > > > if (out != null) { > >> > > > > collect(out) > >> > > > > } > >> > > > > } > >> > > > > > >> > > > > close(){ > >> > > > > waitForPythonFinish() > >> > > > > List<Out> outputs = drainQueue() > >> > > > > outputs.foreach(out -> collect(out)) > >> > > > > } > >> > > > > } > >> > > > > ``` > >> > > > > It works well in lower flink versions until they attempt to do a > >> > > upgrade > >> > > > > recently, the 'flush' logic in the legacy close method of > >> > > `TableFunction` > >> > > > > cannot work properly any more. > >> > > > > > >> > > > > Before proposing the flip, I also considered the `flush()` > >> extension on > >> > > > the > >> > > > > `org.apache.flink.api.common.functions.Function`, because some > sql > >> > > > > operators are also related, but currently not included in the > >> scope of > >> > > > this > >> > > > > flip, maybe we can discuss it in another thread. > >> > > > > > >> > > > > Wish this helps explaining the reason and welcome your comments > >> here! > >> > > > > > >> > > > > Best, > >> > > > > Lincoln Lee > >> > > > > > >> > > > > > >> > > > > Piotr Nowojski <pnowoj...@apache.org> 于2022年9月14日周三 16:56写道： > >> > > > > > >> > > > >> Hi Lincoln, > >> > > > >> > >> > > > >> Thanks for the proposal. Have you seen the old discussion about > >> adding > >> > > > this > >> > > > >> `finish()` method? [1] We didn't add it to UDFs, as we didn't > >> see a > >> > > > >> motivation (maybe we have missed something), and at the same > >> time it > >> > > > wasn't > >> > > > >> that easy. Plain `finish()` wouldn't be enough. Users would > need > >> a way > >> > > > to > >> > > > >> output records from the `finish()` call, so it would have to be > >> typed > >> > > > with > >> > > > >> the user record (`finish(Collector<T> output)`). On the other > >> hand, we > >> > > > >> couldn't find an example where a user would actually need the > >> > > `finish()` > >> > > > >> call in an UDF, as it seemed to us it makes only sense for > >> > > > >> operators/functions that are buffering records. Note back then, > >> during > >> > > > the > >> > > > >> discussion, we were referring to this method as `flush()` or > >> > > `drain()`. > >> > > > >> > >> > > > >> Can you shed some more light and provide more details on the > >> exact > >> > > > >> motivating example behind this proposal? > >> > > > >> > >> > > > >> Best, > >> > > > >> Piotrek > >> > > > >> > >> > > > >> [1] > >> https://lists.apache.org/thread/gmr9r3n3ktojt4bhoxz4t8qho6h7d1rp > >> > > > >> > >> > > > >> śr., 14 wrz 2022 o 08:22 Lincoln Lee <lincoln.8...@gmail.com> > >> > > > napisał(a): > >> > > > >> > >> > > > >>> Hello everyone, > >> > > > >>> > >> > > > >>> I’d like to open a discussion on FLIP-260[1]: expose finish > >> method > >> > > > for > >> > > > >>> UserDefinedFunction, this makes a chance for users who rely on > >> finish > >> > > > >> logic > >> > > > >>> in the legacy close() method (< 1.14) to migrate to the new > >> finish() > >> > > > >>> method. > >> > > > >>> > >> > > > >>> The task lifecycle was changed in FLINK-22972[2]: a new > >> finish() > >> > > > phase > >> > > > >>> was introduced (extracted the ‘finish’ part out of the > ‘close’) > >> and > >> > > > >> removed > >> > > > >>> the dispose() method. This change was also done in table > module > >> > > (e.g., > >> > > > >>> `AbstractMapBundleOperator` for mini-batch operation ) but not > >> > > covered > >> > > > >> the > >> > > > >>> UserDefinedFunction which only exposes open() and close() api > >> for > >> > > > custom > >> > > > >>> usage, those customers who rely on the legacy close() api may > >> > > encounter > >> > > > >>> wrong result or suffer runtime errors after upgrading to the > new > >> > > > version. > >> > > > >>> Strictly speaking, it is a bug caused by the breaking change, > >> but due > >> > > > to > >> > > > >>> the public api change, we propose this flip. > >> > > > >>> > >> > > > >>> Looking forward to your comments or feedback. > >> > > > >>> > >> > > > >>> [1] > >> > > > >>> > >> > > > >>> > >> > > > >> > >> > > > > >> > > > >> > https://cwiki.apache.org/confluence/display/FLINK/FLIP-260%3A+Expose+Finish+Method+For+UserDefinedFunction > >> > > > >>> [2] https://issues.apache.org/jira/browse/FLINK-22972 > >> > > > >>> > >> > > > >>> Best, > >> > > > >>> Lincoln Lee > >> > > > >>> > >> > > > > >> > > > >> > > >
