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From Yuzhao Chen <yuzhao....@gmail.com>
Subject Re: Pluggable JDBC types
Date Mon, 03 Jun 2019 01:12:48 GMT
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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