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 <rube...@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 <nizhi...@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?
