There are tests for builder.values() but there are no tests for literals in
a projection (with, or without a relation), and I didn't know enough to
know to look for values() ..
I have unit tests for literals in projection. I'm happy to contribute to
docs too. I'll get a PR prepared, but before I do that, how would you
recommend I model this?
Option 1: tuple with literals, then projection references them as fields:
builder
.values(new String[] { "f0", "f1" }, 123, "Hello")
.project(builder.field(0), builder.field(1))
.build();
Option 2: tuple with literals, then projection has the same literals (seems
redundant)
builder
.values(new String[] { "f0", "f1" }, 123, "Hello")
.project(builder.literal(123), builder.literal("Hello"))
There is an option 3 where I just have a placeholder values() that is never
referenced, and the projection just has the literals. That seemed too hacky
though.
Thanks,
Andy.
--
Andy Grove
Chief Architect
AgilData - Simple Streaming SQL that Scales
www.agildata.com
On Thu, Nov 19, 2015 at 6:01 PM, Julian Hyde <[email protected]> wrote:
> I think there are tests for RelBuilder.values already.
>
> But it sounds as if we need more documentation in
> http://calcite.apache.org/docs/algebra.html <
> http://calcite.apache.org/docs/algebra.html>. What do you think?
>
> Julian
>
>
>
> > On Nov 19, 2015, at 4:58 PM, Andy Grove <[email protected]> wrote:
> >
> > Got it. Thanks for the detail. I'll submit some unit tests for
> > RelBuilderTest to demonstrate this usage for others.
> >
> >
> > Thanks,
> >
> > Andy.
> >
> > --
> >
> > Andy Grove
> > Chief Architect
> > AgilData - Simple Streaming SQL that Scales
> > www.agildata.com
> >
> >
> > On Thu, Nov 19, 2015 at 5:24 PM, Julian Hyde <[email protected]> wrote:
> >
> >> A Project needs one input. It’s not negotiable.
> >>
> >> If you want to generate a single row, use RelBuilder.values(). There are
> >> several overloaded forms, but for your case probably
> >>
> >> RelBuilder builder;
> >> builder.values(“i”, 123)
> >> .build();
> >>
> >> will do the trick. The VALUES relational operator is a leaf: it has no
> >> inputs, and produces a constant relation. In SQL terms, you are
> generating
> >>
> >> VALUES (123);
> >>
> >> Other overloaded forms of the overloaded values method allow multiple
> >> columns and multiple rows, e.g.
> >>
> >> VALUES (123, ‘a’), (234, ‘bcd’);
> >>
> >> Your mind has probably been poisoned by MySQL and Postgres’ non-standard
> >> FROM-less queries:
> >>
> >> SELECT 123;
> >>
> >> Julian
> >>
> >>
> >>
> >>> On Nov 19, 2015, at 4:16 PM, Andy Grove <[email protected]>
> wrote:
> >>>
> >>> Hi,
> >>>
> >>> I'm now working on a project to translate some proprietary SQL to a
> >> Calcite
> >>> relational plan using the RelBuilder API.
> >>>
> >>> I have a question about literal projections. I can do this OK:
> >>>
> >>> // SELECT 123 FROM EMP
> >>> builder
> >>> .scan("EMP")
> >>> .project(builder.literal(123))
> >>> .build();
> >>>
> >>> However, if I try and do "SELECT 123" without a relation, it fails with
> >> an
> >>> ArrayIndexOutOfBoundsException.
> >>>
> >>> // SELECT 123
> >>> builder
> >>> .project(builder.literal(123))
> >>> .build();
> >>>
> >>> Is there an extra step I need to add a fake relation, or is this a bug?
> >> I'm
> >>> happy to dig in and fix this if it is a bug, but wanted to verify first
> >> if
> >>> this expected to work or not.
> >>>
> >>> Thanks,
> >>>
> >>> Andy.
> >>>
> >>> --
> >>>
> >>> Andy Grove
> >>> Chief Architect
> >>> AgilData - Simple Streaming SQL that Scales
> >>> www.agildata.com
> >>
> >>
>
>
