Hi Timo,
Thanks for the FLIP.
I also tend to think that Option 3 is better.
I would be also interested in a question mentioned by Benchao Li.
And a similar question about nested queries like
`SELECT * FROM (SELECT $rowtime, * FROM t);`
Am I right that it will show `$rowtime` in output ?
On Thu, Jul 27, 2023 at 6:58 AM Benchao Li <libenc...@apache.org> wrote:
> Hi Timo,
>
> Thanks for the FLIP, I also like the idea and option 3 sounds good to me.
>
> I would like to discuss a case which is not mentioned in the current FLIP.
> How are the "System column"s expressed in intermediate result, e.g. Join?
> E.g. `SELECT * FROM t1 JOIN t2`, I guess it should not include "system
> columns" from t1 and t2 as you proposed, and for `SELECT t1.$rowtime, *
> FROM t1 JOIN t2`, it should also be valid.
> Then the question is how to you plan to implement the "system columns", do
> we need to add it to `RelNode` level? Or we just need to do it in the
> parsing/validating phase?
> I'm not sure that Calcite's "system column" feature is fully ready for this
> since the code about this part is imported from the earlier project before
> it gets into Apache, and has not been considered much in the past
> development.
>
>
> Jing Ge <j...@ververica.com.invalid> 于2023年7月26日周三 00:01写道：
>
> > Hi Timo,
> >
> > Thanks for your proposal. It is a very pragmatic feature. Among all
> options
> > in the FLIP, option 3 is one I prefer too and I'd like to ask some
> > questions to understand your thoughts.
> >
> > 1. I did some research on pseudo columns, just out of curiosity, do you
> > know why most SQL systems do not need any prefix with their pseudo
> column?
> > 2. Some platform providers will use ${variable_name} to define their own
> > configurations and allow them to be embedded into SQL scripts. Will there
> > be any conflict with option 3?
> >
> > Best regards,
> > Jing
> >
> > On Tue, Jul 25, 2023 at 7:00 PM Konstantin Knauf <kna...@apache.org>
> > wrote:
> >
> > > Hi Timo,
> > >
> > > this makes sense to me. Option 3 seems reasonable, too.
> > >
> > > Cheers,
> > >
> > > Konstantin
> > >
> > > Am Di., 25. Juli 2023 um 12:53 Uhr schrieb Timo Walther <
> > > twal...@apache.org
> > > >:
> > >
> > > > Hi everyone,
> > > >
> > > > I would like to start a discussion about introducing the concept of
> > > > "System Columns" in SQL and Table API.
> > > >
> > > > The subject sounds bigger than it actually is. Luckily, Flink SQL
> > > > already exposes the concept of metadata columns. And this proposal is
> > > > just a slight adjustment for how metadata columns can be used as
> system
> > > > columns.
> > > >
> > > > The biggest problem of metadata columns currently is that a catalog
> > > > implementation can't provide them by default because they would
> affect
> > > > `SELECT *` when adding another one.
> > > >
> > > > Looking forward to your feedback on FLIP-348:
> > > >
> > > >
> > > >
> > >
> >
> https://cwiki.apache.org/confluence/display/FLINK/FLIP-348%3A+Support+System+Columns+in+SQL+and+Table+API
> > > >
> > > > Thanks,
> > > > Timo
> > > >
> > >
> > >
> > > --
> > > https://twitter.com/snntrable
> > > https://github.com/knaufk
> > >
> >
>
>
> --
>
> Best,
> Benchao Li
>
--
Best regards,
Sergey
