Thanks Godfrey & Jark for your comments! Since both of you mentioned the naming of the parser factory, I'll answer this question first.
I only intend to introduce the pluggable Parser for blink planner. So the BlinkParserFactory will be added to the flink-table-planner-blink module. We already have several factory classes there such as "BlinkPlannerFactory" and "BlinkExecutorFactory". So it seems "BlinkParserFactory" is following the naming convention of existing classes. But I'm also fine with "ParserFactory" if we're going to remove the "blink" prefix anyway. For the concrete implementation, I prefer "DefaultParserFactory". Having a "FlinkParserFactory" in blink planner seems a little weird. We can revisit this when we really get rid of the legacy planner. To answer the other questions: @Godfrey Yes I agree DDLs should also be handled by the HiveParser. That'll give users more consistent experience. The "Go Beyond Hive" section is mainly about decoupling the dialect from hive objects, so that users can write HiveQL to query non-hive tables or call non-hive functions. I think it's in the scope of this FLIP, but it doesn't have to be done in the first release. I'll update the FLIP to be more specific about it. @Jark Creating a new Parser only when dialect changes is a good idea. I'll update the FLIP to mention that. The 3.x new features we need to support in this FLIP include: 1. PK & NOT NULL constraints 2. Alter DB to change location These DDLs are already covered by FLIP-123. Missing them will be a regression. Other new features can be identified with more tests and user feedback, and will be supported incrementally. By "we can use a newer version to support older versions", I mean syntax in the new version is a superset of the old one. But we still need extra efforts to make sure the copied code works with different hive versions, e.g. more shim methods are required. So I'd rather start with a popular version than the newest version. On Wed, Feb 3, 2021 at 11:51 AM Jark Wu <imj...@gmail.com> wrote: > Thanks Rui for the great proposal, I believe this can be very attractive > for many Hive users. > > The FLIP looks good to me in general, I only have some minor comments: > > 1) BlinkParserFactory > IIUC, BlinkParserFactory is located in the flink-table-api-java module with > the Parser interface there. > I suggest renaming it to `ParserFactory`, because it creates Parser instead > of BlinkParser. > And the implementations can be `HiveParserFactory` and > `FlinkParserFactory`. > I think we should avoid the `Blink` keyword in interfaces, blink planner is > already the default planner and > the old planner will be removed in the near future. There will be no > `blink` in the future then. > > 2) "create a new instance each time getParser is called" > Finding parser for every time getParser is called sounds heavy to me. I > think we can improve this by simplify > caching the Parser instance, and creating a new one if current sql-dialect > is different from the cached Parser. > > 3) Hive version > How much code needs to be done to support new features in 3.x based on 2.x? > Is this also included in this FLIP/release? > I don't fully understand this because the FLIP says "we can use a newer > version to support older versions." > > Best, > Jark > > On Wed, 3 Feb 2021 at 11:48, godfrey he <godfre...@gmail.com> wrote: > > > Thanks for bringing up the discussion, Rui! > > > > Regarding the DDL part in the "Introduce HiveParser" section, > > I would like to choose the second option. Because if we could > > use one hive parser to parse all hive SQLs, we need not to copy > > Calcite parser code, and the framework and the code will be very simple. > > > > Regarding the "Go Beyond Hive" section, is that the scope of this FLIP ? > > Could you list all the extensions and give some examples ? > > > > One minor suggestion about the name of ParserImplFactory. > > How about renaming ParserImplFactory to DefaultParserFactory ? > > > > Best, > > Godfrey > > > > Rui Li <lirui.fu...@gmail.com> 于2021年2月3日周三 上午11:16写道： > > > > > Hi Jingsong, > > > > > > Thanks for your comments and they're very good questions. > > > > > > Regarding # Version, we need to do some tradeoff here. Choosing the > > latest > > > 3.x will cover all the features we want to support. But as you said, > 3.x > > > and 2.x can have some differences and requires more efforts to support > > > lower versions. I decided to pick 2.x and evolve from there to support > > new > > > features in 3.x. Because I think most hive users, especially those who > > are > > > likely to be interested in this feature, are still using 2.x or even > 1.x. > > > So the priority is to cover 2.x and 1.x first. > > > > > > Regarding # Hive Codes, in my PoC, I simply copy the code and make as > few > > > changes as possible. I believe we can do some clean up or refactor to > > > reduce it. With that in mind, I expect it to be over 10k lines of java > > > code, and even more if we count ANTLR grammar files as well. > > > > > > Regarding # Functions, you're right that HiveModule is more of a > solution > > > than limitation. I just want to emphasize that HiveModule and hive > > dialect > > > need to be used together to achieve better compatibility. > > > > > > Regarding # Keywords, new hive versions can have more reserved keywords > > > than old versions. Since we're based on hive 2.x code, it may not > provide > > > 100% keyword-compatibility to 1.x users. But I expect it to be good > > enough > > > for most cases. If not, we can provide different grammar files for > lower > > > versions. > > > > > > On Tue, Feb 2, 2021 at 5:10 PM Jingsong Li <jingsongl...@gmail.com> > > wrote: > > > > > > > Thanks Rui for the proposal, I think this FLIP is required by many > > users, > > > > and it is very good to traditional Hive users. I have some confusion: > > > > > > > > # Version > > > > > > > > Which Hive version do you want to choose? Maybe, Hive 3.X and Hive > 2.X > > > have > > > > some differences? > > > > > > > > # Hive Codes > > > > > > > > Can you evaluate how much code we need to copy to our > > > flink-hive-connector? > > > > Do we need to change them? We need to maintain them anyway. > > > > > > > > # Functions > > > > > > > > About Hive functions, I don't think it is a limitation, we are using > > > > HiveModule to be compatible with Hive, right? So it is a solution > > instead > > > > of a limitation. > > > > > > > > # Keywords > > > > > > > > Do you think there will be a keyword problem? Or can we be 100% > > > compatible > > > > with Hive? > > > > > > > > On the whole, the FLIP looks very good and I'm looking forward to it. > > > > > > > > Best, > > > > Jingsong > > > > > > > > On Fri, Dec 11, 2020 at 11:35 AM Zhijiang > > > > <wangzhijiang...@aliyun.com.invalid> wrote: > > > > > > > > > Thanks for the further info and explanations! I have no other > > concerns. > > > > > > > > > > Best, > > > > > Zhijiang > > > > > > > > > > > > > > > ------------------------------------------------------------------ > > > > > From:Rui Li <lirui.fu...@gmail.com> > > > > > Send Time:2020年12月10日(星期四) 20:35 > > > > > To:dev <dev@flink.apache.org>; Zhijiang < > wangzhijiang...@aliyun.com> > > > > > Subject:Re: [DISCUSS] FLIP-152: Hive Query Syntax Compatibility > > > > > > > > > > Hi Zhijiang, > > > > > > > > > > Glad to know you're interested in this FLIP. I wouldn't claim 100% > > > > > compatibility with this FLIP. That's because Flink doesn't have the > > > > > functionalities to support all Hive's features. To list a few > > examples: > > > > > > > > > > 1. Hive allows users to process data with shell scripts -- very > > > > similar > > > > > to UDFs [1] > > > > > 2. Users can compile inline Groovy UDFs and use them in queries > > [2] > > > > > 3. Users can dynamically add/delete jars, or even execute > > arbitrary > > > > > shell command [3] > > > > > > > > > > These features cannot be supported merely by a parser/planner, and > > it's > > > > > open to discussion whether Flink even should support them at all. > > > > > > > > > > So the ultimate goal of this FLIP is to provide Hive syntax > > > compatibility > > > > > to features that are already available in Flink, which I believe > will > > > > cover > > > > > most common use cases. > > > > > > > > > > [1] > > > > > > > > > > > > > > > > > > > > https://cwiki.apache.org/confluence/display/Hive/LanguageManual+Transform#LanguageManualTransform-TRANSFORMExamples > > > > > [2] > > > > > > > > > > > > > > > > > > > > https://community.cloudera.com/t5/Community-Articles/Apache-Hive-Groovy-UDF-examples/ta-p/245060 > > > > > [3] > > > > > > > > > > > > > > > > > > > > https://cwiki.apache.org/confluence/display/Hive/LanguageManual+Cli#LanguageManualCli-HiveInteractiveShellCommands > > > > > > > > > > On Thu, Dec 10, 2020 at 6:11 PM Zhijiang < > wangzhijiang...@aliyun.com > > > > > .invalid> > > > > > wrote: > > > > > > > > > > > Thanks for launching the discussion and the FLIP, Rui! > > > > > > > > > > > > It is really nice to see our continuous efforts for compatibility > > > with > > > > > > Hive and benefiting users in this area. > > > > > > I am only curious that are there any other compatible limitations > > for > > > > > Hive > > > > > > users after this FLIP? Or can I say that the Hive compatibility > is > > > > > > completely resolved after this FLIP? > > > > > > I am interested in the ultimate goal in this area. Maybe it is > out > > of > > > > > this > > > > > > FLIP scope, but still wish some insights from you if possible. :) > > > > > > > > > > > > Best, > > > > > > Zhijiang > > > > > > > > > > > > > > > > > > > ------------------------------------------------------------------ > > > > > > From:Rui Li <lirui.fu...@gmail.com> > > > > > > Send Time:2020年12月10日(星期四) 16:46 > > > > > > To:dev <dev@flink.apache.org> > > > > > > Subject:Re: [DISCUSS] FLIP-152: Hive Query Syntax Compatibility > > > > > > > > > > > > Thanks Kurt for your inputs! > > > > > > > > > > > > I agree we should extend Hive code to support non-Hive tables. I > > have > > > > > > updated the wiki page to remove the limitations you mentioned, > and > > > add > > > > > > typical use cases in the "Motivation" section. > > > > > > > > > > > > Regarding comment #b, the interface is defined in > > > > > flink-table-planner-blink > > > > > > and only used by the blink planner. So I think > "BlinkParserFactory" > > > is > > > > a > > > > > > better name, WDYT? > > > > > > > > > > > > On Mon, Dec 7, 2020 at 12:28 PM Kurt Young <ykt...@gmail.com> > > wrote: > > > > > > > > > > > > > Thanks Rui for starting this discussion. > > > > > > > > > > > > > > I can see the benefit that we improve hive compatibility > further, > > > as > > > > > > quite > > > > > > > some users are asking for this > > > > > > > feature in mailing lists [1][2][3] and some online chatting > tools > > > > such > > > > > as > > > > > > > DingTalk. > > > > > > > > > > > > > > I have 3 comments regarding to the design doc: > > > > > > > > > > > > > > a) Could you add a section to describe the typical use case you > > > want > > > > to > > > > > > > support after this feature is introduced? > > > > > > > In that way, users can also have an impression how to use this > > > > feature > > > > > > and > > > > > > > what the behavior and outcome will be. > > > > > > > > > > > > > > b) Regarding the naming: "BlinkParserFactory", I suggest > renaming > > > it > > > > to > > > > > > > "FlinkParserFactory". > > > > > > > > > > > > > > c) About the two limitations you mentioned: > > > > > > > 1. Only works with Hive tables and the current catalog > needs > > to > > > > be > > > > > a > > > > > > > HiveCatalog. > > > > > > > 2. Queries cannot involve tables/views from multiple > > catalogs. > > > > > > > I assume this is because hive parser and analyzer doesn't > support > > > > > > > referring to a name with "x.y.z" fashion? Since > > > > > > > we can control all the behaviors by leveraging the codes hive > > > > currently > > > > > > > use. Is it possible that we can remove such > > > > > > > limitations? The reason is I'm not sure if users can make the > > whole > > > > > story > > > > > > > work purely depending on hive catalog (that's > > > > > > > the reason why I gave comment #a). If multiple catalogs are > > > involved, > > > > > > with > > > > > > > this limitation I don't think any meaningful > > > > > > > pipeline could be built. For example, users want to stream data > > > from > > > > > > Kafka > > > > > > > to Hive, fully use hive's dialect including > > > > > > > query part. The kafka table could be a temporary table or saved > > in > > > > > > default > > > > > > > memory catalog. > > > > > > > > > > > > > > > > > > > > > [1] > > > > http://apache-flink.147419.n8.nabble.com/calcite-td9059.html#a9118 > > > > > > > [2] > > > > > > > > > http://apache-flink.147419.n8.nabble.com/hive-sql-flink-11-td9116.html > > > > > > > [3] > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/How-to-to-in-Flink-to-support-below-HIVE-SQL-td34162.html > > > > > > > > > > > > > > Best, > > > > > > > Kurt > > > > > > > > > > > > > > > > > > > > > On Wed, Dec 2, 2020 at 10:02 PM Rui Li <lirui.fu...@gmail.com> > > > > wrote: > > > > > > > > > > > > > > > Hi guys, > > > > > > > > > > > > > > > > I'd like to start a discussion about providing HiveQL > > > compatibility > > > > > for > > > > > > > > users connecting to a hive warehouse. FLIP-123 has already > > > covered > > > > > most > > > > > > > > DDLs. So now it's time to complement the other big missing > part > > > -- > > > > > > > queries. > > > > > > > > With FLIP-152, the hive dialect covers more scenarios and > makes > > > it > > > > > even > > > > > > > > easier for users to migrate to Flink. More details are in the > > > FLIP > > > > > wiki > > > > > > > > page [1]. Looking forward to your feedback! > > > > > > > > > > > > > > > > [1] > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > https://cwiki.apache.org/confluence/display/FLINK/FLIP-152%3A+Hive+Query+Syntax+Compatibility > > > > > > > > > > > > > > > > -- > > > > > > > > Best regards! > > > > > > > > Rui Li > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > Best regards! > > > > > > Rui Li > > > > > > > > > > > > > > > > > > > > > > -- > > > > > Best regards! > > > > > Rui Li > > > > > > > > > > > > > > > > > > -- > > > > Best, Jingsong Lee > > > > > > > > > > > > > -- > > > Best regards! > > > Rui Li > > > > > > -- Best regards! Rui Li
