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From "Zhang, Xuefu" <xuef...@alibaba-inc.com>
Subject Re: [DISCUSS] Integrate Flink SQL well with Hive ecosystem
Date Tue, 30 Oct 2018 18:32:21 GMT
Hi all,

I have also shared a design doc on Hive metastore integration that is attached here and also
to FLINK-10556[1]. Please kindly review and share your feedback.


Thanks,
Xuefu

[1] https://issues.apache.org/jira/browse/FLINK-10556
------------------------------------------------------------------
Sender:Xuefu <xuefu.z@alibaba-inc.com>
Sent at:2018 Oct 25 (Thu) 01:08
Recipient:Xuefu <xuefu.z@alibaba-inc.com>; Shuyi Chen <suez1224@gmail.com>
Cc:yanghua1127 <yanghua1127@gmail.com>; Fabian Hueske <fhueske@gmail.com>; dev
<dev@flink.apache.org>; user <user@flink.apache.org>
Subject:Re: [DISCUSS] Integrate Flink SQL well with Hive ecosystem

Hi all,

To wrap up the discussion, I have attached a PDF describing the proposal, which is also attached
to FLINK-10556 [1]. Please feel free to watch that JIRA to track the progress.

Please also let me know if you have additional comments or questions.

Thanks,
Xuefu

[1] https://issues.apache.org/jira/browse/FLINK-10556



------------------------------------------------------------------
Sender:Xuefu <xuefu.z@alibaba-inc.com>
Sent at:2018 Oct 16 (Tue) 03:40
Recipient:Shuyi Chen <suez1224@gmail.com>
Cc:yanghua1127 <yanghua1127@gmail.com>; Fabian Hueske <fhueske@gmail.com>; dev
<dev@flink.apache.org>; user <user@flink.apache.org>
Subject:Re: [DISCUSS] Integrate Flink SQL well with Hive ecosystem

Hi Shuyi,

Thank you for your input. Yes, I agreed with a phased approach and like to move forward fast.
:) We did some work internally on DDL utilizing babel parser in Calcite. While babel makes
Calcite's grammar extensible, at first impression it still seems too cumbersome for a project
when too much extensions are made. It's even challenging to find where the extension is needed!
It would be certainly better if Calcite can magically support Hive QL by just turning on a
flag, such as that for MYSQL_5. I can also see that this could mean a lot of work on Calcite.
Nevertheless, I will bring up the discussion over there and to see what their community thinks.

Would mind to share more info about the proposal on DDL that you mentioned? We can certainly
collaborate on this.

Thanks,
Xuefu

------------------------------------------------------------------
Sender:Shuyi Chen <suez1224@gmail.com>
Sent at:2018 Oct 14 (Sun) 08:30
Recipient:Xuefu <xuefu.z@alibaba-inc.com>
Cc:yanghua1127 <yanghua1127@gmail.com>; Fabian Hueske <fhueske@gmail.com>; dev
<dev@flink.apache.org>; user <user@flink.apache.org>
Subject:Re: [DISCUSS] Integrate Flink SQL well with Hive ecosystem

Welcome to the community and thanks for the great proposal, Xuefu! I think the proposal can
be divided into 2 stages: making Flink to support Hive features, and make Hive to work with
Flink. I agreed with Timo that on starting with a smaller scope, so we can make progress faster.
As for [6], a proposal for DDL is already in progress, and will come after the unified SQL
connector API is done. For supporting Hive syntax, we might need to work with the Calcite
community, and a recent effort called babel (https://issues.apache.org/jira/browse/CALCITE-2280)
in Calcite might help here.

Thanks
Shuyi
On Wed, Oct 10, 2018 at 8:02 PM Zhang, Xuefu <xuefu.z@alibaba-inc.com> wrote:
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
required.
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, etc.
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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