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From Dongjoon Hyun <dongjoon.h...@gmail.com>
Subject Re: [DISCUSS] Spark 2.5 release
Date Sat, 21 Sep 2019 03:46:32 GMT
Do you mean you want to have a breaking API change between 3.0 and 3.1?
I believe we follow Semantic Versioning (
https://spark.apache.org/versioning-policy.html ).

> We just won’t add any breaking changes before 3.1.

Bests,
Dongjoon.


On Fri, Sep 20, 2019 at 11:48 AM Ryan Blue <rblue@netflix.com.invalid>
wrote:

> I don’t think we need to gate a 3.0 release on making a more stable
> version of InternalRow
>
> Sounds like we agree, then. We will use it for 3.0, but there are known
> problems with it.
>
> Thinking we’d have dsv2 working in both 3.x (which will change and
> progress towards more stable, but will have to break certain APIs) and 2.x
> seems like a false premise.
>
> Why do you think we will need to break certain APIs before 3.0?
>
> I’m only suggesting that we release the same support in a 2.5 release that
> we do in 3.0. Since we are nearly finished with the 3.0 goals, it seems
> like we can certainly do that. We just won’t add any breaking changes
> before 3.1.
>
> On Fri, Sep 20, 2019 at 11:39 AM Reynold Xin <rxin@databricks.com> wrote:
>
>> I don't think we need to gate a 3.0 release on making a more stable
>> version of InternalRow, but thinking we'd have dsv2 working in both 3.x
>> (which will change and progress towards more stable, but will have to break
>> certain APIs) and 2.x seems like a false premise.
>>
>> To point out some problems with InternalRow that you think are already
>> pragmatic and stable:
>>
>> The class is in catalyst, which states:
>> https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/package.scala
>>
>> /**
>> * Catalyst is a library for manipulating relational query plans.  All
>> classes in catalyst are
>> * considered an internal API to Spark SQL and are subject to change
>> between minor releases.
>> */
>>
>> There is no even any annotation on the interface.
>>
>> The entire dependency chain were created to be private, and tightly
>> coupled with internal implementations. For example,
>>
>>
>> https://github.com/apache/spark/blob/master/common/unsafe/src/main/java/org/apache/spark/unsafe/types/UTF8String.java
>>
>> /**
>> * A UTF-8 String for internal Spark use.
>> * <p>
>> * A String encoded in UTF-8 as an Array[Byte], which can be used for
>> comparison,
>> * search, see http://en.wikipedia.org/wiki/UTF-8 for details.
>> * <p>
>> * Note: This is not designed for general use cases, should not be used
>> outside SQL.
>> */
>>
>>
>>
>> https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/ArrayData.scala
>>
>> (which again is in catalyst package)
>>
>>
>> If you want to argue this way, you might as well argue we should make the
>> entire catalyst package public to be pragmatic and not allow any changes.
>>
>>
>>
>>
>> On Fri, Sep 20, 2019 at 11:32 AM, Ryan Blue <rblue@netflix.com> wrote:
>>
>>> When you created the PR to make InternalRow public
>>>
>>> This isn’t quite accurate. The change I made was to use InternalRow
>>> instead of UnsafeRow, which is a specific implementation of InternalRow.
>>> Exposing this API has always been a part of DSv2 and while both you and I
>>> did some work to avoid this, we are still in the phase of starting with
>>> that API.
>>>
>>> Note that any change to InternalRow would be very costly to implement
>>> because this interface is widely used. That is why I think we can certainly
>>> consider it stable enough to use here, and that’s probably why UnsafeRow
>>> was part of the original proposal.
>>>
>>> In any case, the goal for 3.0 was not to replace the use of InternalRow,
>>> it was to get the majority of SQL working on top of the interface added
>>> after 2.4. That’s done and stable, so I think a 2.5 release with it is also
>>> reasonable.
>>>
>>> On Fri, Sep 20, 2019 at 11:23 AM Reynold Xin <rxin@databricks.com>
>>> wrote:
>>>
>>> To push back, while I agree we should not drastically change
>>> "InternalRow", there are a lot of changes that need to happen to make it
>>> stable. For example, none of the publicly exposed interfaces should be in
>>> the Catalyst package or the unsafe package. External implementations should
>>> be decoupled from the internal implementations, with cheap ways to convert
>>> back and forth.
>>>
>>> When you created the PR to make InternalRow public, the understanding
>>> was to work towards making it stable in the future, assuming we will start
>>> with an unstable API temporarily. You can't just make a bunch internal APIs
>>> tightly coupled with other internal pieces public and stable and call it a
>>> day, just because it happen to satisfy some use cases temporarily assuming
>>> the rest of Spark doesn't change.
>>>
>>>
>>>
>>> On Fri, Sep 20, 2019 at 11:19 AM, Ryan Blue <rblue@netflix.com> wrote:
>>>
>>> > DSv2 is far from stable right?
>>>
>>> No, I think it is reasonably stable and very close to being ready for a
>>> release.
>>>
>>> > All the actual data types are unstable and you guys have completely
>>> ignored that.
>>>
>>> I think what you're referring to is the use of `InternalRow`. That's a
>>> stable API and there has been no work to avoid using it. In any case, I
>>> don't think that anyone is suggesting that we delay 3.0 until a replacement
>>> for `InternalRow` is added, right?
>>>
>>> While I understand the motivation for a better solution here, I think
>>> the pragmatic solution is to continue using `InternalRow`.
>>>
>>> > If the goal is to make DSv2 work across 3.x and 2.x, that seems too
>>> invasive of a change to backport once you consider the parts needed to make
>>> dsv2 stable.
>>>
>>> I believe that those of us working on DSv2 are confident about the
>>> current stability. We set goals for what to get into the 3.0 release months
>>> ago and have very nearly reached the point where we are ready for that
>>> release.
>>>
>>> I don't think instability would be a problem in maintaining
>>> compatibility between the 2.5 version and the 3.0 version. If we find that
>>> we need to make API changes (other than additions) then we can make those
>>> in the 3.1 release. Because the goals we set for the 3.0 release have been
>>> reached with the current API and if we are ready to release 3.0, we can
>>> release a 2.5 with the same API.
>>>
>>> On Fri, Sep 20, 2019 at 11:05 AM Reynold Xin <rxin@databricks.com>
>>> wrote:
>>>
>>> DSv2 is far from stable right? All the actual data types are unstable
>>> and you guys have completely ignored that. We'd need to work on that and
>>> that will be a breaking change. If the goal is to make DSv2 work across 3.x
>>> and 2.x, that seems too invasive of a change to backport once you consider
>>> the parts needed to make dsv2 stable.
>>>
>>>
>>>
>>> On Fri, Sep 20, 2019 at 10:47 AM, Ryan Blue <rblue@netflix.com.invalid>
>>> wrote:
>>>
>>> Hi everyone,
>>>
>>> In the DSv2 sync this week, we talked about a possible Spark 2.5 release
>>> based on the latest Spark 2.4, but with DSv2 and Java 11 support added.
>>>
>>> A Spark 2.5 release with these two additions will help people migrate to
>>> Spark 3.0 when it is released because they will be able to use a single
>>> implementation for DSv2 sources that works in both 2.5 and 3.0. Similarly,
>>> upgrading to 3.0 won't also require also updating to Java 11 because users
>>> could update to Java 11 with the 2.5 release and have fewer major changes.
>>>
>>> Another reason to consider a 2.5 release is that many people are
>>> interested in a release with the latest DSv2 API and support for DSv2 SQL.
>>> I'm already going to be backporting DSv2 support to the Spark 2.4 line, so
>>> it makes sense to share this work with the community.
>>>
>>> This release line would just consist of backports like DSv2 and Java 11
>>> that assist compatibility, to keep the scope of the release small. The
>>> purpose is to assist people moving to 3.0 and not distract from the 3.0
>>> release.
>>>
>>> Would a Spark 2.5 release help anyone else? Are there any concerns about
>>> this plan?
>>>
>>>
>>> rb
>>>
>>>
>>> --
>>> Ryan Blue
>>> Software Engineer
>>> Netflix
>>>
>>>
>>>
>>>
>>> --
>>> Ryan Blue
>>> Software Engineer
>>> Netflix
>>>
>>>
>>>
>>>
>>> --
>>> Ryan Blue
>>> Software Engineer
>>> Netflix
>>>
>>
>>
>
> --
> Ryan Blue
> Software Engineer
> Netflix
>

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