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From Jacques Nadeau <jacq...@dremio.com>
Subject Re: select from table with options
Date Sat, 07 Nov 2015 05:53:11 GMT
Since EXTEND is custom functionality, it seems reasonable that we could
have a switch. Given that SQL Server and Postgres support it seems
reasonable to support the table functions without the TABLE syntax.

I for one definitely think the TABLE syntax is much more confusing to use,
especially in the example that we're looking to support, such as:

select * from dfs.`/myfolder/mytable` (type => 'CSV', fieldDelimiter =>
'|', skipFirstRow => true)

This seems much clearer than:

select * from TABLE(dfs.`/myfolder/mytable` (type => 'CSV', fieldDelimiter
=> '|', skipFirstRow => true))

It also looks much more like a hint to the table (which is our goal).







--
Jacques Nadeau
CTO and Co-Founder, Dremio

On Fri, Nov 6, 2015 at 9:15 PM, Julian Hyde <jhyde@apache.org> wrote:

> Thanks for doing the legwork and finding what the other vendors do. It is
> indeed compelling that SQL Server and Postgres go beyond the standard an
> make the TABLE keyword optional.
>
> I tried that syntax in Calcite and discovered that there is a clash with
> one of our own (few) extensions. In
> https://issues.apache.org/jira/browse/CALCITE-493 we added the EXTENDS
> clause. You can write
>
>   SELECT *
>   FROM Emp EXTEND (favoriteBand VARCHAR(100), golfHandicap INTEGER)
>   WHERE goldHandicap < 10;
>
> to tell Calcite that there are two undeclared columns in the Emp table but
> you would like to use them in this particular query. We chose to make the
> EXTEND keyword optional, so you could instead write
>
>   SELECT *
>   FROM Emp (favoriteBand VARCHAR(100), golfHandicap INTEGER)
>   WHERE goldHandicap < 10;
>
> That is uncomfortably close to
>
>   SELECT *
>   FROM EmpFunction (favoriteBand, golfHandicap);
>
> so we would require
>
>   SELECT *
>   FROM TABLE(EmpFunction (favoriteBand, golfHandicap));
>
> if EmpFunction was a table-function. You could combine the two forms like
> this:
>
>   SELECT *
>   FROM TABLE(EmpFunction (favoriteBand, golfHandicap)) EXTEND
> (anotherAttribute INTEGER);
>
> We could revisit whether EXTEND is optional, I suppose. But we should also
> ask whether requiring folks to type TABLE is such a hardship.
>
> Julian
>
>
> > On Nov 6, 2015, at 2:20 PM, Julien Le Dem <julien@dremio.com> wrote:
> >
> > - Table function syntax: I did a quick search and it seems there's no
> > consensus about this.
> > It seems that Posgres [1] and SQL Server [2] both allow calling table
> > functions without the table(...) wrapper while Oracle [3] and DB2 [4]
> > expect it.
> > MySQL does not have table functions [5]
> > 2 for, 2 against and 1 undecided: that's a draw :)
> > Would it be reasonable to allow a switch in the grammar generation to
> have
> > a posgres compatible syntax? Currently in Drill we use the MySQL like
> > syntax (back ticks for identifiers etc)
> >
> > [1] http://www.postgresql.org/docs/7.3/static/xfunc-tablefunctions.html
> > [2] https://technet.microsoft.com/en-us/library/aa214485(v=sql.80).aspx
> > [3] https://oracle-base.com/articles/misc/pipelined-table-functions
> > [4] http://www.ibm.com/developerworks/ibmi/library/i-power-of-udtf/
> > [5]
> >
> http://stackoverflow.com/questions/12163666/mysql-function-to-return-a-table
> >
> > - It seems a simple change in SqlCallBinding fixes the function
> > overloading: https://github.com/apache/calcite/pull/166/files
> > But that seems too easy to be true. Possibly this method is called more
> > than once (before and after the function has been resolved?)
> >
> > FYI this would happen only when using named parameter. We do want to
> > overload in this case, which is why I'm looking into it.
> >
> > I'll fill a JIRA for my other branch
> >
> > Julien
> >
> > On Thu, Nov 5, 2015 at 5:39 PM, Julian Hyde <jhyde@apache.org> wrote:
> >
> >>
> >> On Nov 5, 2015, at 5:00 PM, Julien Le Dem <julien@dremio.com> wrote:
> >>
> >> TL;DR: TableMacro works for me; I need help with a bug in Calcite when
> >> there's more than 1 function with the same name.
> >>
> >>
> >> Yes; see below.
> >>
> >> FYI: I have a prototype of TableMacro working in Drill. For now just
> being
> >> able to specify the delimiter for csv files.
> >> So it seem the answer to my question 1) is that TableMacros are the way
> to
> >> go.
> >> I'm still wondering about *3) is the table(...) wrapping syntax
> >> necessary?*
> >>
> >>
> >> Consider:
> >>
> >> select * from myTable as f(x, y)
> >> select * from myTable f(x, y)
> >> select * from myFunction(x, y)
> >>
> >> #1 and #2 mean the same thing; #2 and #3 look awfully similar. Also, if
> f
> >> is a function with zero arguments, could you invoke it like this?:
> >>
> >> select * from f
> >>
> >> I don’t know the actual rationale. But I know that the SQL standards
> >> people in their wisdom decided to add a keyword to disambiguate.
> >>
> >> I had to fix some things in Calcite to enable this:
> >> https://github.com/dremio/calcite/pull/1/files
> >> Drill uses Frameworks.getPlanner() that does not seem to be used in
> >> Calcite for the Maze example.
> >> Which is why some hooks were missing.
> >>
> >>
> >> Can you log a jira case to track this bug?
> >>
> >>
> >> I think I found a bug in Calcite but I'd need help to fix it.
> >> Here is a test that reproduces the problem:
> >> https://github.com/apache/calcite/pull/166
> >> If we return more than 1 TableFunction with the same name, we get a NPE
> >> later on.
> >>
> >>
> >> Yes, I knew there was a problem with overloading. Please log a JIRA case
> >> on resolution of overloaded functions when invoked with named arguments.
> >> (It probably applies to all functions, not just table functions.) The
> fix
> >> will take a while (if you wait for me to write it).
> >>
> >> For now please tell your users not to overload. :)
> >>
> >>
> >> Julian
> >>
> >>
> >
> >
> > --
> > Julien
>
>

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