Thanks, I have removed the contents about the “STORED” keyword, we may introduce that in the future if there is requests.
Also thanks all the reviewers for the design doc, I have resolved all the questions/suggestions in the doc at this time. I will kick off a voting thread shortly as there were no comments in this thread so far, so I would assume there are no objections :) Best, Danny Chan 在 2019年10月24日 +0800 PM5:11，Kurt Young <ykt...@gmail.com>，写道： > +1 to move to a future section. By deleting it I mean remove from > the content describing the current processing procedure. > > Best, > Kurt > > > On Thu, Oct 24, 2019 at 5:01 PM Timo Walther <twal...@apache.org> wrote: > > > Having an MVP and a limited scope sounds good to me. But I would not > > remove the STORED keyword entirely from the document. > > > > It shows that we have a long-term vision. Instead of deleting this > > content, I would move it to a Outlook/Future Work section. > > > > Regards, > > Timo > > > > > > On 24.10.19 10:55, Jark Wu wrote: > > > +1 to remove “STORED” related content. We can add them when user > > requires. > > > Others looks good to me in general. > > > > > > Thanks, > > > Jark > > > > > > > > > > 在 2019年10月24日，14:58，Kurt Young <ykt...@gmail.com> 写道： > > > > > > > > Hi Danny, > > > > > > > > Thanks for preparing this design document. IMO It's a very useful > > > > feature, especially combined with time attribute support to specify > > > > watermark in DDL. > > > > > > > > The design doc looks quite good, but I would suggest to reduce the > > > > scope of the first version. Like we don't have to support "STORED" > > > > in the first MVP version, and you can also delete related content in > > > > document to make it more clean and easier to understand. > > > > > > > > Best, > > > > Kurt > > > > > > > > > > > > On Tue, Sep 17, 2019 at 9:18 PM Qi Luo <luoqi...@gmail.com> wrote: > > > > > > > > > Fantastic! We're also very interested in this feature. > > > > > > > > > > +Boxiu > > > > > > > > > > On Tue, Sep 17, 2019 at 11:31 AM Danny Chan <yuzhao....@gmail.com> > > wrote: > > > > > > > > > > > In umbrella task FLINK-10232 we have introduced CREATE TABLE grammar > > in > > > > > > our new module flink-sql-parser. And we proposed to use computed > > column > > > > > to > > > > > > describe the time attribute of process time in the design doc FLINK > > SQL > > > > > > DDL, so user may create a table with process time attribute as > > follows: > > > > > > create table T1( > > > > > > a int, > > > > > > b bigint, > > > > > > c varchar, > > > > > > d as PROCTIME, > > > > > > ) with ( > > > > > > 'k1' = 'v1', > > > > > > 'k2' = 'v2' > > > > > > ); > > > > > > > > > > > > The column d would be a process time attribute for table T1. > > > > > > > > > > > > Besides that, computed columns have several other use cases, such as > > > > > > these [2]: > > > > > > > > > > > > > > > > > > • Virtual generated columns can be used as a way to simplify and > > > > > > unify > > > > > > queries. A complicated condition can be defined as a generated > > > > > > column > > and > > > > > > referred to from multiple queries on the table to ensure that all of > > them > > > > > > use exactly the same condition. > > > > > > • Stored generated columns can be used as a materialized cache for > > > > > > complicated conditions that are costly to calculate on the fly. > > > > > > • Generated columns can simulate functional indexes: Use a generated > > > > > > column to define a functional expression and index it. This can be > > useful > > > > > > for working with columns of types that cannot be indexed directly, > > such > > > > > as > > > > > > JSON columns. > > > > > > • For stored generated columns, the disadvantage of this approach is > > that > > > > > > values are stored twice; once as the value of the generated column > > > > > > and > > > > > once > > > > > > in the index. > > > > > > • If a generated column is indexed, the optimizer recognizes query > > > > > > expressions that match the column definition and uses indexes from > > > > > > the > > > > > > column as appropriate during query execution(Not supported yet). > > > > > > > > > > > > > > > > > > > > > > > > Computed columns are introduced in SQL-SERVER-2016 [1], MYSQL-5.6 > > > > > > [2] > > and > > > > > > ORACLE-11g [3]. > > > > > > > > > > > > This is the design doc: > > > > > > > > > > > > > > > > > > > https://docs.google.com/document/d/110TseRtTCphxETPY7uhiHpu-dph3NEesh3mYKtJ7QOY/edit?usp=sharing > > > > > > > > > > > > Any suggestions are appreciated, thanks. > > > > > > > > > > > > [1] > > > > > > > > > > > > > https://docs.microsoft.com/en-us/sql/relational-databases/tables/specify-computed-columns-in-a-table?view=sql-server-2016 > > > > > > [2] > > > > > > > > > > > > > https://dev.mysql.com/doc/refman/5.7/en/create-table-generated-columns.html > > > > > > [3] https://oracle-base.com/articles/11g/virtual-columns-11gr1 > > > > > > > > > > > > Best, > > > > > > Danny Chan > > > > > > > > > > > > > > >
