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From Jörn Franke <jornfra...@gmail.com>
Subject Re: [DISCUSS] Integrate Flink SQL well with Hive ecosystem
Date Thu, 11 Oct 2018 05:54:25 GMT
Would it maybe make sense to provide Flink as an engine on Hive („flink-on-Hive“)? Eg to
address 4,5,6,8,9,10. this could be more loosely coupled than integrating hive in all possible
flink core modules and thus introducing a very tight dependency to Hive in the core.
1,2,3 could be achieved via a connector based on the Flink Table API.
Just as a proposal to start this Endeavour as independent projects (hive engine, connector)
to avoid too tight coupling with Flink. Maybe in a more distant future if the Hive integration
is heavily demanded one could then integrate it more tightly if needed. 

What is meant by 11?
> Am 11.10.2018 um 05:01 schrieb Zhang, Xuefu <xuefu.z@alibaba-inc.com>:
> Hi Fabian/Vno,
> Thank you very much for your encouragement inquiry. Sorry that I didn't see Fabian's
email until I read Vino's response just now. (Somehow Fabian's went to the spam folder.)
> My proposal contains long-term and short-terms goals. Nevertheless, the effort will focus
on the following areas, including Fabian's list:
> 1. Hive metastore connectivity - This covers both read/write access, which means Flink
can make full use of Hive's metastore as its catalog (at least for the batch but can extend
for streaming as well).
> 2. Metadata compatibility - Objects (databases, tables, partitions, etc) created by Hive
can be understood by Flink and the reverse direction is true also.
> 3. Data compatibility - Similar to #2, data produced by Hive can be consumed by Flink
and vise versa.
> 4. Support Hive UDFs - For all Hive's native udfs, Flink either provides its own implementation
or make Hive's implementation work in Flink. Further, for user created UDFs in Hive, Flink
SQL should provide a mechanism allowing user to import them into Flink without any code change
> 5. Data types -  Flink SQL should support all data types that are available in Hive.
> 6. SQL Language - Flink SQL should support SQL standard (such as SQL2003) with extension
to support Hive's syntax and language features, around DDL, DML, and SELECT queries.
> 7.  SQL CLI - this is currently developing in Flink but more effort is needed.
> 8. Server - provide a server that's compatible with Hive's HiverServer2 in thrift APIs,
such that HiveServer2 users can reuse their existing client (such as beeline) but connect
to Flink's thrift server instead.
> 9. JDBC/ODBC drivers - Flink may provide its own JDBC/ODBC drivers for other application
to use to connect to its thrift server
> 10. Support other user's customizations in Hive, such as Hive Serdes, storage handlers,
> 11. Better task failure tolerance and task scheduling at Flink runtime.
> As you can see, achieving all those requires significant effort and across all layers
in Flink. However, a short-term goal could  include only core areas (such as 1, 2, 4, 5, 6,
7) or start  at a smaller scope (such as #3, #6).
> Please share your further thoughts. If we generally agree that this is the right direction,
I could come up with a formal proposal quickly and then we can follow up with broader discussions.
> Thanks,
> Xuefu
> ------------------------------------------------------------------
> Sender:vino yang <yanghua1127@gmail.com>
> Sent at:2018 Oct 11 (Thu) 09:45
> Recipient:Fabian Hueske <fhueske@gmail.com>
> Cc:dev <dev@flink.apache.org>; Xuefu <xuefu.z@alibaba-inc.com>; user <user@flink.apache.org>
> Subject:Re: [DISCUSS] Integrate Flink SQL well with Hive ecosystem
> Hi Xuefu,
> Appreciate this proposal, and like Fabian, it would look better if you can give more
details of the plan.
> Thanks, vino.
> Fabian Hueske <fhueske@gmail.com> 于2018年10月10日周三 下午5:27写道:
> Hi Xuefu,
> Welcome to the Flink community and thanks for starting this discussion! Better Hive integration
would be really great!
> Can you go into details of what you are proposing? I can think of a couple ways to improve
Flink in that regard:
> * Support for Hive UDFs
> * Support for Hive metadata catalog
> * Support for HiveQL syntax
> * ???
> Best, Fabian
> Am Di., 9. Okt. 2018 um 19:22 Uhr schrieb Zhang, Xuefu <xuefu.z@alibaba-inc.com>:
> Hi all,
> Along with the community's effort, inside Alibaba we have explored Flink's potential
as an execution engine not just for stream processing but also for batch processing. We are
encouraged by our findings and have initiated our effort to make Flink's SQL capabilities
full-fledged. When comparing what's available in Flink to the offerings from competitive data
processing engines, we identified a major gap in Flink: a well integration with Hive ecosystem.
This is crucial to the success of Flink SQL and batch due to the well-established data ecosystem
around Hive. Therefore, we have done some initial work along this direction but there are
still a lot of effort needed.
> We have two strategies in mind. The first one is to make Flink SQL full-fledged and well-integrated
with Hive ecosystem. This is a similar approach to what Spark SQL adopted. The second strategy
is to make Hive itself work with Flink, similar to the proposal in [1]. Each approach bears
its pros and cons, but they don’t need to be mutually exclusive with each targeting at different
users and use cases. We believe that both will promote a much greater adoption of Flink beyond
stream processing.
> We have been focused on the first approach and would like to showcase Flink's batch and
SQL capabilities with Flink SQL. However, we have also planned to start strategy #2 as the
follow-up effort.
> I'm completely new to Flink(, with a short bio [2] below), though many of my colleagues
here at Alibaba are long-time contributors. Nevertheless, I'd like to share our thoughts and
invite your early feedback. At the same time, I am working on a detailed proposal on Flink
SQL's integration with Hive ecosystem, which will be also shared when ready.
> While the ideas are simple, each approach will demand significant effort, more than what
we can afford. Thus, the input and contributions from the communities are greatly welcome
and appreciated.
> Regards,
> Xuefu
> References:
> [1] https://issues.apache.org/jira/browse/HIVE-10712
> [2] Xuefu Zhang is a long-time open source veteran, worked or working on many projects
under Apache Foundation, of which he is also an honored member. About 10 years ago he worked
in the Hadoop team at Yahoo where the projects just got started. Later he worked at Cloudera,
initiating and leading the development of Hive on Spark project in the communities and across
many organizations. Prior to joining Alibaba, he worked at Uber where he promoted Hive on
Spark to all Uber's SQL on Hadoop workload and significantly improved Uber's cluster efficiency.

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