[jira] [Commented] (CALCITE-5046) SqlTypeFactorylmpl#leastRestrictiveByCast incorrect results with MAP types

["Francesco Guardiani (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-5046?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17506999#comment-17506999 ] 

Francesco Guardiani commented on CALCITE-5046:
----------------------------------------------

After some investigation I found out that on master this bug does not reproduce. I tried to add this test:


{code:java}
/**
 * Test case for CALCITE-5046.
 */
@Test void testLeastRestrictiveForMapsWithMixedCharVarChar() {
  SqlTypeFixture f = new SqlTypeFixture();

  // (CHAR(1), VARCHAR(6)) MAP
  // (VARCHAR(2147483647), VARCHAR(2147483647)) MAP
  // (CHAR(1), CHAR(1)) MAP

  List<RelDataType> inputs = Lists.newArrayList(
    f.typeFactory.createMapType(f.sqlChar1, f.typeFactory.createSqlType(SqlTypeName.VARCHAR, 6)),
      f.typeFactory.createMapType(f.sqlVarchar, f.sqlVarchar),
      f.typeFactory.createMapType(f.sqlChar1, f.sqlChar1)
  );

  RelDataType leastRestrictive = f.typeFactory.leastRestrictive(inputs);
  assertThat(leastRestrictive.getSqlTypeName(), is(SqlTypeName.MAP));
  assertThat(leastRestrictive.isNullable(), is(false));
  assertThat(leastRestrictive.getKeyType().getSqlTypeName(), is(SqlTypeName.VARCHAR));
  assertThat(leastRestrictive.getValueType().getSqlTypeName(), is(SqlTypeName.VARCHAR));
} {code}
And it passes fine, so I guess we can close this one. Sorry for the noise!

> SqlTypeFactorylmpl#leastRestrictiveByCast incorrect results with MAP types
> --------------------------------------------------------------------------
>
>                 Key: CALCITE-5046
>                 URL: https://issues.apache.org/jira/browse/CALCITE-5046
>             Project: Calcite
>          Issue Type: Bug
>    Affects Versions: 1.26.0
>            Reporter: Francesco Guardiani
>            Priority: Major
>
> SqlTypeFactorylmpl#leastRestrictiveByCast returns incorrect results when the two input types are maps, with key and value types castable.
> For example, trying with this input:
> {code:sql}
> (CHAR(1), VARCHAR(6)) MAP
> (VARCHAR(2147483647), VARCHAR(2147483647)) MAP
> (CHAR(1), CHAR(1)) MAP
> {code}
> Returns the type {{(CHAR(1), CHAR(1)) MAP}}, which is incorrect as i would expect {{(VARCHAR(2147483647), VARCHAR(2147483647)) MAP}} as result.
> My analysis is that this is caused by {{SqlTypeUtil#canCastFrom}} which doesn't properly support MAP types, in particular when coerce = false. Adding this chunk of code here https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/sql/type/SqlTypeUtil.java#L877:
> {code:java}
>         if (fromTypeName == toTypeName && fromTypeName == SqlTypeName.MAP) {
>             return canCastFrom(toType.getKeyType(), fromType.getKeyType(), coerce)
>                     && canCastFrom(toType.getValueType(), fromType.getValueType(), coerce);
>         }
> {code}
> Solves the issue, as now the MAP type casting check is not falling back to {{SqlTypeMappingRule}} anymore.
> I tested with 1.26, but looking on master, it sounds like the problem applies to later versions as well https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/sql/type/SqlTypeUtil.java#L814



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