+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 > >>>> > >>> > >
