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From Stamatis Zampetakis <zabe...@gmail.com>
Subject Re: Pluggable JDBC types
Date Tue, 04 Jun 2019 16:23:16 GMT
I am not sure what problem exactly we are trying to solve here (sorry for
that).
>From what I understood so far the requirement is to introduce a new
built-in SQL type (i.e., TEXT).
However, I am still trying to understand why do we need this.
Are we going to treat TEXT and VARCHAR differently?

On Tue, Jun 4, 2019 at 5:18 PM Muhammad Gelbana <m.gelbana@gmail.com> wrote:

> Thanks Lai, I beleive your analysis is correct.
>
> Which brings up another question:
> Is it ok if we add support for what I'm trying to do here ? I can gladly
> work on that but I need to know if it will be accepted.
>
> Thanks,
> Gelbana
>
>
> On Tue, Jun 4, 2019 at 8:38 AM Lai Zhou <hhlai1990@gmail.com> wrote:
>
> > @Muhammad Gelbana,I think you just register an alias-name 'TEXT' for the
> > SqlType  'VARCHAR'.
> > The parser did the right thing here, see
> >
> >
> https://github.com/apache/calcite/blob/9721283bd0ce46a337f51a3691585cca8003e399/core/src/main/java/org/apache/calcite/sql/validate/SqlValidatorImpl.java#L1566
> > When the parser encountered a 'text' SqlIdentifier, it would get the type
> > from the rootSchema, the type was SqlTypeName.VARCHAR here , that you
> > registered before.
> > If you really need a new sqlType named 'text' rather than an alias-name,
> I
> > guess you need to introduce a new kind of SqlTypeName .
> >
> >
> >
> >
> > Muhammad Gelbana <m.gelbana@gmail.com> 于2019年6月3日周一 下午6:54写道:
> >
> > > Is that different from what I mentioned in my Jira comment ? Here it is
> > > again:
> > >
> > > Connection connection = DriverManager.getConnection("jdbc:calcite:",
> > info);
> > >
> > >
> >
> connection.unwrap(CalciteConnection.class).getRootSchema().unwrap(CalciteSchema.class).add("
> > > *TEXT*", new RelProtoDataType() {
> > >
> > >             @Override
> > >             public RelDataType apply(RelDataTypeFactory factory) {
> > >                 return
> > > factory.createTypeWithNullability(factory.createJavaType(String.class),
> > > false);
> > >                 // return
> > >
> > >
> >
> factory.createTypeWithNullability(factory.createSqlType(SqlTypeName.VARCHAR),
> > > false); // Has the same effect
> > >             }
> > >         });
> > >
> > > This still returns a column type name of VARCHAR, not *TEXT*.
> > >
> > > I tried providing the type through the model as the UdtTest does but
> it's
> > > giving me the same output.
> > >
> > > Thanks,
> > > Gelbana
> > >
> > >
> > > On Mon, Jun 3, 2019 at 9:59 AM Julian Hyde <jhyde@apache.org> wrote:
> > >
> > > > User-defined types are probably the way to go.
> > > >
> > > > > On Jun 2, 2019, at 8:28 PM, Muhammad Gelbana <m.gelbana@gmail.com>
> > > > wrote:
> > > > >
> > > > > That was my first attempt and it worked, but Julian pointed out
> that
> > I
> > > > can
> > > > > support a type without modifying the parser (which I prefer) but
I
> > > > couldn't
> > > > > get it to return the column type name as I wish.
> > > > >
> > > > > Thanks,
> > > > > Gelbana
> > > > >
> > > > >
> > > > > On Mon, Jun 3, 2019 at 3:13 AM Yuzhao Chen <yuzhao.cyz@gmail.com>
> > > wrote:
> > > > >
> > > > >> You don’t need to, just define a new type name in parser[1]
and
> > > > translate
> > > > >> it to VARCHAR is okey.
> > > > >>
> > > > >> [1]
> > > > >>
> > > >
> > >
> >
> https://github.com/apache/calcite/blob/b0e83c469ff57257c1ea621ff943ca76f626a9b7/server/src/main/codegen/config.fmpp#L375
> > > > >>
> > > > >> Best,
> > > > >> Danny Chan
> > > > >> 在 2019年6月3日 +0800 AM6:09,Muhammad Gelbana <m.gelbana@gmail.com
> >,写道:
> > > > >>> That I understand now. But how can I support casting to TEXT
and
> > > having
> > > > >> the
> > > > >>> returned column type name as TEXT (ie. Not VARCHAR) ?
> > > > >>>
> > > > >>> Thanks,
> > > > >>> Gelbana
> > > > >>>
> > > > >>>
> > > > >>> On Sun, Jun 2, 2019 at 7:41 PM Julian Hyde <jhyde@apache.org>
> > wrote:
> > > > >>>
> > > > >>>> The parser should only parse, not validate. This is a
very
> > important
> > > > >>>> organizing principle for the parser.
> > > > >>>>
> > > > >>>> If I write “x :: text” or “x :: foo” it is up
to the type system
> > > > >>>> (implemented in the validator and elsewhere) to figure
out
> whether
> > > > >> “text”
> > > > >>>> or “foo” are valid types.
> > > > >>>>
> > > > >>>> Logically, “x :: foo” is the same as “CAST(x AS
foo)”. The
> parser
> > > > >> should
> > > > >>>> produce the same SqlCall in both cases. Then the parser’s
job is
> > > done.
> > > > >>>>
> > > > >>>> Julian
> > > > >>>>
> > > > >>>>
> > > > >>>>> On Jun 2, 2019, at 6:42 AM, Muhammad Gelbana <
> > m.gelbana@gmail.com>
> > > > >>>> wrote:
> > > > >>>>>
> > > > >>>>> I'm trying to support the PostgreSQL TEXT type[1].
It's
> > basically a
> > > > >>>> VARCHAR.
> > > > >>>>>
> > > > >>>>> As Julian mentioned in his comment on Jira, I don't
need to
> > define
> > > a
> > > > >>>>> keyword to achieve what I need so I tried exploring
that and
> here
> > > is
> > > > >>>> what I
> > > > >>>>> observed so far:
> > > > >>>>>
> > > > >>>>> 1. If I define a new keyword in the parser, I face
no trouble
> > > > >> whatsoever
> > > > >>>>> except for the numerous wiring I need to do for
> > RexToLixTranslator,
> > > > >>>>> JavaTypeFactoryImpl, SqlTypeAssignmentRules and SqlTypeName.
I
> > > won't
> > > > >> be
> > > > >>>>> suprised if I'm missing anything but doing what I
did at first
> > > > >> managed to
> > > > >>>>> get my queries through.
> > > > >>>>>
> > > > >>>>> 2. If I define the type by plugging it in through
the root
> > schema,
> > > I
> > > > >> face
> > > > >>>>> two problems: a) The field cannot be declared as
nullable
> because
> > > the
> > > > >>>> query
> > > > >>>>> I'm using for testing gets data from (VALUES()) which
doesn't
> > > produce
> > > > >>>> null
> > > > >>>>> values, so an exception is thrown. b) The returned
column type
> > name
> > > > >> is
> > > > >>>>> VARCHAR (although I delcared the new plugged type
name to be
> > TEXT),
> > > > >> the
> > > > >>>>> returned type number is valid though (Types.VARCHAR
= 12)
> > > > >>>>>
> > > > >>>>> I think I'm doing something wrong that causes (2.a)
but (2.b)
> > > seems a
> > > > >>>> like
> > > > >>>>> a bug to me. What do you think ?
> > > > >>>>>
> > > > >>>>> [1] https://issues.apache.org/jira/browse/CALCITE-3108
> > > > >>>>>
> > > > >>>>> Thanks,
> > > > >>>>> Gelbana
> > > > >>>>
> > > > >>>>
> > > > >>
> > > >
> > > >
> > >
> >
>

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