+1 for Matei's suggestion! Bests, Dongjoon.
On Sat, Sep 21, 2019 at 5:44 PM Matei Zaharia <matei.zaha...@gmail.com> wrote: > If the goal is to get people to try the DSv2 API and build DSv2 data > sources, can we recommend the 3.0-preview release for this? That would get > people shifting to 3.0 faster, which is probably better overall compared to > maintaining two major versions. There’s not that much else changing in 3.0 > if you already want to update your Java version. > > On Sep 21, 2019, at 2:45 PM, Ryan Blue <rb...@netflix.com.INVALID> wrote: > > > If you insist we shouldn't change the unstable temporary API in 3.x . . . > > Not what I'm saying at all. I said we should carefully consider whether a > breaking change is the right decision in the 3.x line. > > All I'm suggesting is that we can make a 2.5 release with the feature and > an API that is the same as the one in 3.0. > > > I also don't get this backporting a giant feature to 2.x line > > I am planning to do this so we can use DSv2 before 3.0 is released. Then > we can have a source implementation that works in both 2.x and 3.0 to make > the transition easier. Since I'm already doing the work, I'm offering to > share it with the community. > > > On Sat, Sep 21, 2019 at 2:36 PM Reynold Xin <r...@databricks.com> wrote: > >> Because for example we'd need to move the location of InternalRow, >> breaking the package name. If you insist we shouldn't change the unstable >> temporary API in 3.x to maintain compatibility with 3.0, which is totally >> different from my understanding of the situation when you exposed it, then >> I'd say we should gate 3.0 on having a stable row interface. >> >> I also don't get this backporting a giant feature to 2.x line ... as >> suggested by others in the thread, DSv2 would be one of the main reasons >> people upgrade to 3.0. What's so special about DSv2 that we are doing this? >> Why not abandoning 3.0 entirely and backport all the features to 2.x? >> >> >> >> On Sat, Sep 21, 2019 at 2:31 PM, Ryan Blue <rb...@netflix.com> wrote: >> >>> Why would that require an incompatible change? >>> >>> We *could* make an incompatible change and remove support for >>> InternalRow, but I think we would want to carefully consider whether that >>> is the right decision. And in any case, we would be able to keep 2.5 and >>> 3.0 compatible, which is the main goal. >>> >>> On Sat, Sep 21, 2019 at 2:28 PM Reynold Xin <r...@databricks.com> wrote: >>> >>> How would you not make incompatible changes in 3.x? As discussed the >>> InternalRow API is not stable and needs to change. >>> >>> On Sat, Sep 21, 2019 at 2:27 PM Ryan Blue <rb...@netflix.com> wrote: >>> >>> > Making downstream to diverge their implementation heavily between >>> minor versions (say, 2.4 vs 2.5) wouldn't be a good experience >>> >>> You're right that the API has been evolving in the 2.x line. But, it is >>> now reasonably stable with respect to the current feature set and we should >>> not need to break compatibility in the 3.x line. Because we have reached >>> our goals for the 3.0 release, we can backport at least those features to >>> 2.x and confidently have an API that works in both a 2.x release and is >>> compatible with 3.0, if not 3.1 and later releases as well. >>> >>> > I'd rather say preparation of Spark 2.5 should be started after Spark >>> 3.0 is officially released >>> >>> The reason I'm suggesting this is that I'm already going to do the work >>> to backport the 3.0 release features to 2.4. I've been asked by several >>> people when DSv2 will be released, so I know there is a lot of interest in >>> making this available sooner than 3.0. If I'm already doing the work, then >>> I'd be happy to share that with the community. >>> >>> I don't see why 2.5 and 3.0 are mutually exclusive. We can work on 2.5 >>> while preparing the 3.0 preview and fixing bugs. For DSv2, the work is >>> about complete so we can easily release the same set of features and API in >>> 2.5 and 3.0. >>> >>> If we decide for some reason to wait until after 3.0 is released, I >>> don't know that there is much value in a 2.5. The purpose is to be a step >>> toward 3.0, and releasing that step after 3.0 doesn't seem helpful to me. >>> It also wouldn't get these features out any sooner than 3.0, as a 2.5 >>> release probably would, given the work needed to validate the incompatible >>> changes in 3.0. >>> >>> > DSv2 change would be the major backward incompatibility which Spark >>> 2.x users may hesitate to upgrade >>> >>> As I pointed out, DSv2 has been changing in the 2.x line, so this is >>> expected. I don't think it will need incompatible changes in the 3.x line. >>> >>> On Fri, Sep 20, 2019 at 9:25 PM Jungtaek Lim <kabh...@gmail.com> wrote: >>> >>> Just 2 cents, I haven't tracked the change of DSv2 (though I needed to >>> deal with this as the change made confusion on my PRs...), but my bet is >>> that DSv2 would be already changed in incompatible way, at least who works >>> for custom DataSource. Making downstream to diverge their implementation >>> heavily between minor versions (say, 2.4 vs 2.5) wouldn't be a good >>> experience - especially we are not completely closed the chance to further >>> modify DSv2, and the change could be backward incompatible. >>> >>> If we really want to bring the DSv2 change to 2.x version line to let >>> end users avoid forcing to upgrade Spark 3.x to enjoy new DSv2, I'd rather >>> say preparation of Spark 2.5 should be started after Spark 3.0 is >>> officially released, honestly even later than that, say, getting some >>> reports from Spark 3.0 about DSv2 so that we feel DSv2 is OK. I hope we >>> don't make Spark 2.5 be a kind of "tech-preview" which Spark 2.4 users may >>> be frustrated to upgrade to next minor version. >>> >>> Btw, do we have any specific target users for this? Personally DSv2 >>> change would be the major backward incompatibility which Spark 2.x users >>> may hesitate to upgrade, so they might be already prepared to migrate to >>> Spark 3.0 if they are prepared to migrate to new DSv2. >>> >>> On Sat, Sep 21, 2019 at 12:46 PM Dongjoon Hyun <dongjoon.h...@gmail.com> >>> wrote: >>> >>> 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 <rb...@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 <r...@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 <rb...@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 <r...@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 <rb...@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 <r...@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 <rb...@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 >>> >>> >>> >>> -- >>> Name : Jungtaek Lim >>> Blog : http://medium.com/@heartsavior >>> Twitter : http://twitter.com/heartsavior >>> LinkedIn : http://www.linkedin.com/in/heartsavior >>> >>> >>> >>> -- >>> Ryan Blue >>> Software Engineer >>> Netflix >>> >>> >>> >>> -- >>> Ryan Blue >>> Software Engineer >>> Netflix >>> >> >> > > -- > Ryan Blue > Software Engineer > Netflix > > >
