@Rascal Thanks for looking at this new feature! There is a lot of content in these two flips and we will prepare a more detailed user documentation before the 1.16 release.
First of all, unlike regular join, the lookup join only triggers the lookup action (access the dimension table) through the records of the stream table, and the updates of the dimension table itself do not actively trigger the updating results to downstream. For your example, whether retry is enabled or not, only the first "+[order1, id1, 10]" will sent to downstream (because only one order record has come), the new updates of dimension table "10:02 -> (id1, 12)" will not trigger updates. For the retry support in FLIP-234, it only provide a 'lookup_miss' retry predicate which is to retry if can not find it (not always equivalent to the complete join condition [1]), and not to trigger the retry if can find a non-null value from the dimension table. If more complex value check logic required, a viable way is to implement a custom `AsyncRetryPredicate` in DataStream API (as FLIP-232 introduced). [1]: for different connector, the index-lookup capability maybe different, e.g., HBase can lookup on rowkey only (by default, without secondary index), while RDBMS can provided more powerful index-lookup capabilities let's see the lookup join example from flink document( https://nightlies.apache.org/flink/flink-docs-master/docs/dev/table/sql/queries/joins/#lookup-join) if the query with a join condition "ON o.customer_id = c.id and c.country = 'US'" -- enrich each order with customer informationSELECT o.order_id, o.total, c.country, c.zipFROM Orders AS o JOIN Customers FOR SYSTEM_TIME AS OF o.proc_time AS c ON o.customer_id = c.id and c.country = 'US'; for the dimension table in mysql, all of the columns (id & country) can be used as index-lookup condition -- Customers is backed by the JDBC connector and can be used for lookup joinsCREATE TEMPORARY TABLE Customers ( id INT, name STRING, country STRING, zip STRING) WITH ( 'connector' = 'jdbc', 'url' = 'jdbc:mysql://mysqlhost:3306/customerdb', 'table-name' = 'customers'); while if the same table stored in HBase (with no secondary index), only the 'id' column (rowkey in HBase) can be the index-lookup condition -- Customers is backed by the JDBC connector and can be used for lookup joinsCREATE TEMPORARY TABLE Customers ( id INT, name STRING, country STRING, zip STRING, PRIMARY KEY (id) NOT ENFORCED) WITH ( 'connector' = 'hbase-xxx', ...); so, the 'lookup_miss' retry predicte may result differently in different connectors. wish this can helps. Best, Lincoln Lee Rascal Wu <stayras...@gmail.com> 于2022年8月11日周四 10:32写道： > Hi here, > > Sorry for digging up this old email. > > May I consult one question about what's the final behavior we expected > after we enabled retryable mechanism. I viewed the FLIP-232 & FLIP-234, but > I didn't get a clear answer as lacking of some knowledge. > > Let me take a example there, let's assume we have a dim table(id, price), > the record(id1) existed in dim table before 10:00, and then it was updated > in business system at 10:01, but delay updated in dim table at 10:02. the > record timeline as follow: > 10:00 -> (id1, 10) > 10:00 -> the id1 records was been updated, but delayed persistency or sync > to dim table. > 10:02 -> (id1, 12) > > And a Flink application processes an order record that will join the dim > table at 10:01, so it will output an event +[order1, id1, 10]. > And if we enable retry mechanism no matter it's sync or async, does it mean > there will be two events sink to downstream: > 1. retract event: -[order1, id1, 10] > 2. new event: +[order1, id1, 12] > > does the above all behavior is what we expected to solve the delay update > for dimension table? > > > Lincoln Lee <lincoln.8...@gmail.com> 于2022年6月7日周二 12:19写道： > > > Hi everyone, > > > > I started a vote for this FLIP [1], please vote there or ask additional > > questions here. [2] > > > > [1] https://lists.apache.org/thread/bb0kqjs8co3hhmtklmwptws4fc4rz810 > > [2] https://lists.apache.org/thread/9k1sl2519kh2n3yttwqc00p07xdfns3h > > > > > > Best, > > Lincoln Lee > > > > > > Lincoln Lee <lincoln.8...@gmail.com> 于2022年6月2日周四 15:51写道： > > > > > Hi everyone, > > > > > > When reviewing the name of the hint option 'miss-retry'='true|false', I > > > feel the current name is not precise enough, it might be easier to > > > understand by using the retry-predicate directly from flip-232, > > > e.g. 'retry-predicate'='lookup-miss', which has the additional benefit > of > > > extensibility(maybe more retry condition in the future). > > > > > > Jark & Jingsong, do you have any suggestions? If we agree with the name > > > 'retry-predicate' or other better candidate, I'll update the FLIP. > > > > > > Best, > > > Lincoln Lee > > > > > > > > > Lincoln Lee <lincoln.8...@gmail.com> 于2022年6月2日周四 11:23写道： > > > > > >> Hi everyone, > > >> > > >> I've updated the FLIP[1] based on this discussion thread that we agree > > to > > >> have a single unified 'LOOKUP' hint and also a related part in > > FLIP-221[2] > > >> which is mainly for the necessity of the common table option > > >> 'lookup.async'. > > >> > > >> The main updates are: > > >> 1. the new unified 'LOOKUP' hint, make retry support both on sync and > > >> async lookup > > >> 2. clarify the default choice of the planner for those connectors > which > > >> have both sync and async lookup capabilities, and how to deal with the > > >> query hint > > >> 3. will add a followup issue to discuss whether to remove the > > >> 'lookup.async' option in HBase connector. > > >> > > >> [1] > > >> > > > https://cwiki.apache.org/confluence/display/FLINK/FLIP-234%3A+Support+Retryable+Lookup+Join+To+Solve+Delayed+Updates+Issue+In+External+Systems > > >> [2] https://lists.apache.org/thread/1vokqdnnt01yycl7y1p74g556cc8yvtq > > >> > > >> Best, > > >> Lincoln Lee > > >> > > >> > > >> Lincoln Lee <lincoln.8...@gmail.com> 于2022年6月1日周三 16:03写道： > > >> > > >>> Hi Jingsong, > > >>> > > >>> There will be no change for connectors with only one capability (sync > > or > > >>> async). > > >>> > > >>> Query hint works in a best effort manner, so if users specifies a > hint > > >>> with invalid option, the query plan keeps unchanged, e.g., use > > >>> LOOKUP('table'='customer', 'async'='true'), but backend lookup source > > only > > >>> implemented the sync lookup function, then the async lookup hint > takes > > no > > >>> effect. > > >>> > > >>> For these connectors which can have both capabilities of async and > sync > > >>> lookup, our advice for the connector developer is implementing both > > sync > > >>> and async interfaces if both capabilities have suitable use cases, > and > > the > > >>> planner can decide which capability is the preferable one based on > cost > > >>> model or maybe other mechanism (another use case is exactly what > we're > > >>> discussing here, users can give the query hint), otherwise choose one > > >>> interface to implement. > > >>> > > >>> Also, this should be clarified for the lookup function related APIs. > > >>> > > >>> Best, > > >>> Lincoln Lee > > >>> > > >>> > > >>> Jingsong Li <jingsongl...@gmail.com> 于2022年6月1日周三 15:18写道： > > >>> > > >>>> Hi Lincoln, > > >>>> > > >>>> > It's better making decisions at the query level when a connector > has > > >>>> both > > >>>> capabilities. > > >>>> > > >>>> Can you clarify the mechanism? > > >>>> - only sync connector: What connector developers should do > > >>>> - only async connector: What connector developers should do > > >>>> - both async and sync connector: What connector developers should do > > >>>> > > >>>> Best, > > >>>> Jingsong > > >>>> > > >>>> On Wed, Jun 1, 2022 at 2:29 PM Lincoln Lee <lincoln.8...@gmail.com> > > >>>> wrote: > > >>>> > > >>>> > Hi Jingsong, > > >>>> > > > >>>> > Thanks for your feedback! > > >>>> > > > >>>> > Yes, the existing HBase connector use an option 'lookup.async' to > > >>>> control > > >>>> > its lookup source implementations that exposed to the planner, > > >>>> however it's > > >>>> > a private option for the HBase connector only, so it will not > affect > > >>>> the > > >>>> > common API. > > >>>> > > > >>>> > And as discussed in the mailing thread of FLIP-221[1], we got a > > >>>> consensus > > >>>> > that do not make it as a common option. It's better making > decisions > > >>>> at the > > >>>> > query level when a connector has both capabilities. > > >>>> > > > >>>> > So if everything goes well, we should discuss it whether to > > deprecate > > >>>> > the 'lookup.async' > > >>>> > or not for HBase connector after the hint been done. > > >>>> > > > >>>> > This will be mentioned in the Compatibility part of this FLIP[2]. > > >>>> > > > >>>> > WDYT? > > >>>> > > > >>>> > [1]: > > https://lists.apache.org/thread/v76g8v1o9sjdho9kbzlgjyv38l2oynox > > >>>> > [2]: > > >>>> > > > >>>> > > > >>>> > > > https://cwiki.apache.org/confluence/display/FLINK/FLIP-234%3A+Support+Retryable+Lookup+Join+To+Solve+Delayed+Updates+Issue+In+External+Systems?src=contextnavpagetreemode > > >>>> > > > >>>> > Best, > > >>>> > Lincoln Lee > > >>>> > > > >>>> > > > >>>> > Jingsong Li <jingsongl...@gmail.com> 于2022年6月1日周三 14:11写道： > > >>>> > > > >>>> > > Hi Lincoln, > > >>>> > > > > >>>> > > The unified lookup hint is what I want. > > >>>> > > > > >>>> > > And I like 'async'='true|false' option. > > >>>> > > > > >>>> > > But there is a compatibility issue, as I remember if async is > > >>>> currently > > >>>> > > controlled by connector, and this may also require some API > > changes? > > >>>> > > > > >>>> > > We need to have a clear story for the connector combined with > this > > >>>> > option: > > >>>> > > - only sync connector > > >>>> > > - only async connector > > >>>> > > - both async and sync connector > > >>>> > > > > >>>> > > Best, > > >>>> > > Jingsong > > >>>> > > > > >>>> > > On Mon, May 30, 2022 at 3:55 PM Lincoln Lee < > > lincoln.8...@gmail.com > > >>>> > > > >>>> > > wrote: > > >>>> > > > > >>>> > > > Thanks Jark for your quick response and the consensus! > > >>>> > > > > > >>>> > > > And I will update the FLIP after Jingsong or other developers > > >>>> confirm > > >>>> > > that > > >>>> > > > there is no problem. > > >>>> > > > > > >>>> > > > Best, > > >>>> > > > Lincoln Lee > > >>>> > > > > > >>>> > > > > > >>>> > > > Jark Wu <imj...@gmail.com> 于2022年5月30日周一 15:49写道： > > >>>> > > > > > >>>> > > > > Thanks for the update. > > >>>> > > > > > > >>>> > > > > The unified lookup hint looks good to me. > > >>>> > > > > And thanks for explaining ALLOW_UNORDERED. > > >>>> > > > > > > >>>> > > > > Best, > > >>>> > > > > Jark > > >>>> > > > > > > >>>> > > > > On Mon, 30 May 2022 at 15:31, Lincoln Lee < > > >>>> lincoln.8...@gmail.com> > > >>>> > > > wrote: > > >>>> > > > > > > >>>> > > > > > Hi Jark & Jingsong, > > >>>> > > > > > > > >>>> > > > > > Thanks for your feedback! > > >>>> > > > > > > > >>>> > > > > > 1.) support retry on sync lookup > > >>>> > > > > > I also agree with supporting it, this will be useful for > > >>>> connectors > > >>>> > > > that > > >>>> > > > > > don't have asynchronous lookup implementations and can > also > > >>>> solve > > >>>> > the > > >>>> > > > > ASYNC > > >>>> > > > > > non-target problem to some extent(because the retrying is > > >>>> blocking > > >>>> > > for > > >>>> > > > > sync > > >>>> > > > > > lookup, and may accumulate delay, but it maybe acceptable > > for > > >>>> the > > >>>> > > case > > >>>> > > > > that > > >>>> > > > > > most or all data want to do a delayed lookup). > > >>>> > > > > > > > >>>> > > > > > For the api perspective, we can do some unification. Let's > > >>>> think of > > >>>> > > the > > >>>> > > > > > whole user story for lookup join: > > >>>> > > > > > > > >>>> > > > > > ASYNC_LOOKUP vs SYNC_LOOKUP can share a common one: > LOOKUP > > by > > >>>> > > > different > > >>>> > > > > > hint option values: 'async'='true|false' > > >>>> > > > > > > > >>>> > > > > > ASYNC_LOOKUP_MISS_RETRY vs SYNC_LOOKUP_MISS_RETRY can > share > > >>>> the > > >>>> > > > > > LOOKUP_MISS_RETRY with hint option: > > 'miss-retry'='true|false' > > >>>> > > > > > > > >>>> > > > > > we can use one single hint LOOKUP with different hint > > options > > >>>> > > > > > ('async'='true|false', 'miss-retry'='true|false') to cover > > all > > >>>> > > related > > >>>> > > > > > functionalities. > > >>>> > > > > > Compared to multiple hints with different subsets of > > >>>> > functionality, a > > >>>> > > > > > single hint may be easier for users to understand and use, > > and > > >>>> > > specific > > >>>> > > > > > parameters can be quickly found through documentation > > >>>> > > > > > > > >>>> > > > > > the support matrix will be: > > >>>> > > > > > lookup support async retry > > >>>> > > > > > sync w/o retry N N > > >>>> > > > > > sync w/ retry N Y > > >>>> > > > > > async w/o retry Y N > > >>>> > > > > > async w/ retry Y Y > > >>>> > > > > > > > >>>> > > > > > and the available hint options for each mode: > > >>>> > > > > > mode support hint options > > >>>> > > > > > async async'='true' > > >>>> > > > > > 'output-mode'='ordere|allow-unordered' > > >>>> > > > > > 'capacity'='100' > > >>>> > > > > > 'timeout'='180s' > > >>>> > > > > > retry miss-retry'='true' > > >>>> > > > > > 'retry-strategy'='fixed-delay' > > >>>> > > > > > 'delay'='10s' > > >>>> > > > > > 'max-attempts'='3' > > >>>> > > > > > > > >>>> > > > > > > > >>>> > > > > > 2.) 'allow-unordered' vs 'unordered' for > > >>>> > > > > > 'table.exec.async-lookup.output-mode' > > >>>> > > > > > Yes, make it align with DataStream Api maybe more > intuitive, > > >>>> but > > >>>> > > > there's > > >>>> > > > > > some difference in table layer that makes the > > >>>> 'allow-unordered' > > >>>> > > > > meaningful: > > >>>> > > > > > updates in the pipeline need to be processed in order, > > >>>> > > ALLOW_UNORDERED > > >>>> > > > > > means if users allow unordered result, it will attempt to > > use > > >>>> > > > > > AsyncDataStream.OutputMode.UNORDERED when it does not > affect > > >>>> the > > >>>> > > > > > correctness of the result, otherwise ORDERED will be still > > >>>> used. > > >>>> > > > > > > > >>>> > > > > > Another choice is that when the user specifies unordered > > mode, > > >>>> > > planner > > >>>> > > > > > throws an error when it finds that it may affect > > correctness. > > >>>> But > > >>>> > > this > > >>>> > > > is > > >>>> > > > > > not user-friendly and is not consistent with the customary > > >>>> > treatment > > >>>> > > of > > >>>> > > > > > invalid query hints(best effort). > > >>>> > > > > > > > >>>> > > > > > I opened a pr https://github.com/apache/flink/pull/19759 > > for > > >>>> the > > >>>> > new > > >>>> > > > > > option > > >>>> > > > > > 'table.exec.async-lookup.output-mode' and also a > discussion > > on > > >>>> > > > > FLINK-27625: > > >>>> > > > > > add query hint 'ASYNC_LOOKUP' for async lookup join(Since > > the > > >>>> > changes > > >>>> > > > > were > > >>>> > > > > > relatively minor, no new flip was created) > > >>>> > > > > > > > >>>> > > > > > If we can reach a consensus on the single unified hint, > > e.g., > > >>>> > LOOKUP, > > >>>> > > > > then > > >>>> > > > > > FLINK-27625 can be covered. > > >>>> > > > > > > > >>>> > > > > > WDYT? > > >>>> > > > > > > > >>>> > > > > > Best, > > >>>> > > > > > Lincoln Lee > > >>>> > > > > > > > >>>> > > > > > > > >>>> > > > > > Jark Wu <imj...@gmail.com> 于2022年5月27日周五 21:04写道： > > >>>> > > > > > > > >>>> > > > > > > Hi Lincoln, > > >>>> > > > > > > > > >>>> > > > > > > Delayed Dim Join is a frequently requested feature, it's > > >>>> exciting > > >>>> > > to > > >>>> > > > > see > > >>>> > > > > > > this feature is on the road. > > >>>> > > > > > > The FLIP looks good to me in general. I only left some > > minor > > >>>> > > > comments. > > >>>> > > > > > > > > >>>> > > > > > > 1) support retry for sync lookup > > >>>> > > > > > > I'm also fine with the idea proposed by Jingsong. But > this > > >>>> > doesn't > > >>>> > > > > > conflict > > >>>> > > > > > > with the FLIP and can > > >>>> > > > > > > be future work. It would be great if we can determine > the > > >>>> APIs > > >>>> > > first. > > >>>> > > > > > > > > >>>> > > > > > > 1) "allow-unordered" => "unordered" > > >>>> > > > > > > I would prefer the "unordered" output mode rather than > > >>>> > > > > "allow-unordered". > > >>>> > > > > > > Because this fully aligns with the DataStream behaviors > > and > > >>>> > avoids > > >>>> > > > > > > confusion on the differences. > > >>>> > > > > > > I understand the purpose that adding a "allow" prefix > > here, > > >>>> but I > > >>>> > > > think > > >>>> > > > > > the > > >>>> > > > > > > semantic is fine to just > > >>>> > > > > > > use "unordered" here. We didn't see any users confused > > about > > >>>> > > > > > > OutputMode#UNORDERED. > > >>>> > > > > > > > > >>>> > > > > > > Best, > > >>>> > > > > > > Jark > > >>>> > > > > > > > > >>>> > > > > > > > > >>>> > > > > > > > > >>>> > > > > > > On Fri, 27 May 2022 at 12:58, Jingsong Li < > > >>>> > jingsongl...@gmail.com> > > >>>> > > > > > wrote: > > >>>> > > > > > > > > >>>> > > > > > > > Thanks Lincoln for your proposal. > > >>>> > > > > > > > > > >>>> > > > > > > > Take a look at `strategy: fixed-delay delay: duration, > > >>>> e.g., > > >>>> > 10s > > >>>> > > > > > > > max-attempts: integer, e.g., 3`. > > >>>> > > > > > > > > > >>>> > > > > > > > Are these options only for async? It looks like normal > > >>>> lookups > > >>>> > > work > > >>>> > > > > > too? > > >>>> > > > > > > > > > >>>> > > > > > > > One thing is: most of the lookup functions seem to be > > >>>> > synchronous > > >>>> > > > > now? > > >>>> > > > > > > > There are not so many asynchronous ones? > > >>>> > > > > > > > > > >>>> > > > > > > > Best, > > >>>> > > > > > > > Jingsong > > >>>> > > > > > > > > > >>>> > > > > > > > On Tue, May 24, 2022 at 11:48 AM Lincoln Lee < > > >>>> > > > lincoln.8...@gmail.com > > >>>> > > > > > > > >>>> > > > > > > > wrote: > > >>>> > > > > > > > > > >>>> > > > > > > > > Hi all, > > >>>> > > > > > > > > > > >>>> > > > > > > > > Considering the new common table option > > >>>> 'lookup.max-retries' > > >>>> > > > > proposed > > >>>> > > > > > > in > > >>>> > > > > > > > > FLIP-221[1] which is commonly used for exception > > >>>> handling in > > >>>> > > > > > connector > > >>>> > > > > > > > > implementation, we should clearly distinguish > > >>>> > > ASYNC_LOOKUP_RETRY > > >>>> > > > > from > > >>>> > > > > > > it > > >>>> > > > > > > > to > > >>>> > > > > > > > > avoid confusing users. > > >>>> > > > > > > > > > > >>>> > > > > > > > > To do so, the name ASYNC_LOOKUP_RETRY can change to > > >>>> > > > > > > > > ASYNC_LOOKUP_MISS_RETRY, and as the name implies, > > >>>> restrict > > >>>> > it > > >>>> > > to > > >>>> > > > > > > support > > >>>> > > > > > > > > retries only for lookup misses and no longer include > > >>>> > exceptions > > >>>> > > > > (for > > >>>> > > > > > > sql > > >>>> > > > > > > > > connectors, let the connector implementer decide how > > to > > >>>> > handle > > >>>> > > > > > > exceptions > > >>>> > > > > > > > > since there are various kinds of retryable > exceptions > > >>>> and can > > >>>> > > not > > >>>> > > > > > retry > > >>>> > > > > > > > > ones). > > >>>> > > > > > > > > > > >>>> > > > > > > > > The FLIP[2] has been updated. > > >>>> > > > > > > > > > > >>>> > > > > > > > > [1] > > >>>> > > > > > > > > > > >>>> > > > > > > > > > > >>>> > > > > > > > > > >>>> > > > > > > > > >>>> > > > > > > > >>>> > > > > > > >>>> > > > > > >>>> > > > > >>>> > > > >>>> > > > https://cwiki.apache.org/confluence/display/FLINK/FLIP-221%3A+Abstraction+for+lookup+source+cache+and+metric > > >>>> > > > > > > > > [2] > > >>>> > > > > > > > > > > >>>> > > > > > > > > > > >>>> > > > > > > > > > >>>> > > > > > > > > >>>> > > > > > > > >>>> > > > > > > >>>> > > > > > >>>> > > > > >>>> > > > >>>> > > > https://cwiki.apache.org/confluence/display/FLINK/FLIP-234%3A+Support+Retryable+Lookup+Join+To+Solve+Delayed+Updates+Issue+In+External+Systems > > >>>> > > > > > > > > > > >>>> > > > > > > > > > > >>>> > > > > > > > > Best, > > >>>> > > > > > > > > Lincoln Lee > > >>>> > > > > > > > > > > >>>> > > > > > > > > > > >>>> > > > > > > > > Lincoln Lee <lincoln.8...@gmail.com> 于2022年5月19日周四 > > >>>> 18:24写道： > > >>>> > > > > > > > > > > >>>> > > > > > > > > > Dear Flink developers, > > >>>> > > > > > > > > > > > >>>> > > > > > > > > > I would like to open a discussion on FLIP 234 [1] > to > > >>>> > support > > >>>> > > > > > > retryable > > >>>> > > > > > > > > > lookup join to solve delayed updates issue, as a > > >>>> pre-work > > >>>> > for > > >>>> > > > > this > > >>>> > > > > > > > > > solution, we proposed FLIP-232[2] which adds a > > generic > > >>>> > retry > > >>>> > > > > > support > > >>>> > > > > > > > for > > >>>> > > > > > > > > > Async I/O. > > >>>> > > > > > > > > > We prefer to offer this retry capability via query > > >>>> hints, > > >>>> > > > similar > > >>>> > > > > > to > > >>>> > > > > > > > new > > >>>> > > > > > > > > > join hints proposed in FLINK-27625[3] & > FLIP-204[4]. > > >>>> > > > > > > > > > > > >>>> > > > > > > > > > This feature is backwards compatible and > > >>>> transparently to > > >>>> > > > > > connectors. > > >>>> > > > > > > > For > > >>>> > > > > > > > > > existing connectors which implements > > >>>> AsyncTableFunction, > > >>>> > can > > >>>> > > > > easily > > >>>> > > > > > > > > enable > > >>>> > > > > > > > > > async retry via the new join hint. > > >>>> > > > > > > > > > > > >>>> > > > > > > > > > [1] > > >>>> > > > > > > > > > > > >>>> > > > > > > > > > > >>>> > > > > > > > > > >>>> > > > > > > > > >>>> > > > > > > > >>>> > > > > > > >>>> > > > > > >>>> > > > > >>>> > > > >>>> > > > https://cwiki.apache.org/confluence/display/FLINK/FLIP-234%3A+Support+Retryable+Lookup+Join+To+Solve+Delayed+Updates+Issue+In+External+Systems > > >>>> > > > > > > > > > [2] > > >>>> > > > > > > > > > > > >>>> > > > > > > > > > > >>>> > > > > > > > > > >>>> > > > > > > > > >>>> > > > > > > > >>>> > > > > > > >>>> > > > > > >>>> > > > > >>>> > > > >>>> > > > https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=211883963 > > >>>> > > > > > > > > > [3] > > >>>> > > > > > > > >>>> https://lists.apache.org/thread/jm9kg33wk9z2bvo2b0g5bp3n5kfj6qv8 > > >>>> > > > > > > > > > [4] > > >>>> > > > > > > > > > > > >>>> > > > > > > > > > > >>>> > > > > > > > > > >>>> > > > > > > > > >>>> > > > > > > > >>>> > > > > > > >>>> > > > > > >>>> > > > > >>>> > > > >>>> > > > https://cwiki.apache.org/confluence/display/FLINK/FLIP-204:+Introduce+Hash+Lookup+Join > > >>>> > > > > > > > > > > > >>>> > > > > > > > > > Best, > > >>>> > > > > > > > > > Lincoln Lee > > >>>> > > > > > > > > > > > >>>> > > > > > > > > > > >>>> > > > > > > > > > >>>> > > > > > > > > >>>> > > > > > > > >>>> > > > > > > >>>> > > > > > >>>> > > > > >>>> > > > >>>> > > >>> > > >
