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Posted to dev@calcite.apache.org by Николай Ижиков <ni...@apache.org> on 2023/01/16 15:45:19 UTC
[DISCUSS] CAST DOUBLE to BOOLEAN
Hello.
Right now, Calcite allows to cast FLOAT, DOUBLE expressions to BOOLEAN.
But, results is always `false`. Cast works as `java.lang.Boolean.parseBoolean` call and always return false for anything except «true» string(`Primitive#parse`).
Simple additional test for `InterpreterTest` shows this:
```
@Test void testDoubleCast() {
sql("SELECT CAST(CAST('0.0' AS DOUBLE) AS BOOLEAN)").returnsRows("[false]");
sql("SELECT CAST(CAST('0.1' AS DOUBLE) AS BOOLEAN)").returnsRows("[false]");
sql("SELECT CAST(CAST('1.0' AS DOUBLE) AS BOOLEAN)").returnsRows("[false]");
sql("SELECT CAST(CAST('42' AS DOUBLE) AS BOOLEAN)").returnsRows("[false]");
}
```
Other database, such as Postgres, disallow cast from double(float) to boolean:
```
psql (14.6 (Homebrew))
Type "help" for help.
postgres=# SELECT CAST(CAST('1' AS float) AS BOOLEAN);
ERROR: cannot cast type double precision to boolean
LINE 1: SELECT CAST(CAST('1' AS float) AS BOOLEAN);
^
postgres=#
```
Do we really need to support this?
I think Calcite should disallow this kind of conversion for better user experience.
I can provide PR to implement proposed behavior
What do you think?
Re: [DISCUSS] CAST DOUBLE to BOOLEAN
Posted by Julian Hyde <jh...@apache.org>.
I agree, we should not support converting (explicitly or implicitly)
any numeric type to BOOLEAN. We made a mistake when we documented the
conversions (the table did not match actual or intended behavior)
I have just logged https://issues.apache.org/jira/browse/CALCITE-5485
to ensure that the documentation, intended behavior, and tests are in
sync. I'd be grateful if someone would fix it.
On Tue, Jan 17, 2023 at 12:36 AM Ruben Q L <ru...@gmail.com> wrote:
>
> Hello,
>
> IIRC there was a discussion some time ago about this topic, see comments in
> https://issues.apache.org/jira/browse/CALCITE-4777 and related tickets (all
> of them still open).
>
> Best,
> Ruben
>
>
> On Mon, Jan 16, 2023 at 3:46 PM Николай Ижиков <ni...@apache.org> wrote:
>
> > Hello.
> >
> > Right now, Calcite allows to cast FLOAT, DOUBLE expressions to BOOLEAN.
> > But, results is always `false`. Cast works as
> > `java.lang.Boolean.parseBoolean` call and always return false for anything
> > except «true» string(`Primitive#parse`).
> >
> > Simple additional test for `InterpreterTest` shows this:
> >
> > ```
> > @Test void testDoubleCast() {
> > sql("SELECT CAST(CAST('0.0' AS DOUBLE) AS
> > BOOLEAN)").returnsRows("[false]");
> > sql("SELECT CAST(CAST('0.1' AS DOUBLE) AS
> > BOOLEAN)").returnsRows("[false]");
> > sql("SELECT CAST(CAST('1.0' AS DOUBLE) AS
> > BOOLEAN)").returnsRows("[false]");
> > sql("SELECT CAST(CAST('42' AS DOUBLE) AS
> > BOOLEAN)").returnsRows("[false]");
> > }
> > ```
> >
> > Other database, such as Postgres, disallow cast from double(float) to
> > boolean:
> >
> > ```
> > psql (14.6 (Homebrew))
> > Type "help" for help.
> >
> > postgres=# SELECT CAST(CAST('1' AS float) AS BOOLEAN);
> > ERROR: cannot cast type double precision to boolean
> > LINE 1: SELECT CAST(CAST('1' AS float) AS BOOLEAN);
> > ^
> > postgres=#
> > ```
> >
> > Do we really need to support this?
> > I think Calcite should disallow this kind of conversion for better user
> > experience.
> > I can provide PR to implement proposed behavior
> >
> > What do you think?
Re: [DISCUSS] CAST DOUBLE to BOOLEAN
Posted by Ruben Q L <ru...@gmail.com>.
Hello,
IIRC there was a discussion some time ago about this topic, see comments in
https://issues.apache.org/jira/browse/CALCITE-4777 and related tickets (all
of them still open).
Best,
Ruben
On Mon, Jan 16, 2023 at 3:46 PM Николай Ижиков <ni...@apache.org> wrote:
> Hello.
>
> Right now, Calcite allows to cast FLOAT, DOUBLE expressions to BOOLEAN.
> But, results is always `false`. Cast works as
> `java.lang.Boolean.parseBoolean` call and always return false for anything
> except «true» string(`Primitive#parse`).
>
> Simple additional test for `InterpreterTest` shows this:
>
> ```
> @Test void testDoubleCast() {
> sql("SELECT CAST(CAST('0.0' AS DOUBLE) AS
> BOOLEAN)").returnsRows("[false]");
> sql("SELECT CAST(CAST('0.1' AS DOUBLE) AS
> BOOLEAN)").returnsRows("[false]");
> sql("SELECT CAST(CAST('1.0' AS DOUBLE) AS
> BOOLEAN)").returnsRows("[false]");
> sql("SELECT CAST(CAST('42' AS DOUBLE) AS
> BOOLEAN)").returnsRows("[false]");
> }
> ```
>
> Other database, such as Postgres, disallow cast from double(float) to
> boolean:
>
> ```
> psql (14.6 (Homebrew))
> Type "help" for help.
>
> postgres=# SELECT CAST(CAST('1' AS float) AS BOOLEAN);
> ERROR: cannot cast type double precision to boolean
> LINE 1: SELECT CAST(CAST('1' AS float) AS BOOLEAN);
> ^
> postgres=#
> ```
>
> Do we really need to support this?
> I think Calcite should disallow this kind of conversion for better user
> experience.
> I can provide PR to implement proposed behavior
>
> What do you think?