[CALCITE-4150] RelToSqlConverter does not support null without a cast: "Unsupported type when convertTypeToSpec: NULL"

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.24.0
• Fix Version/s: 1.25.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Anton Haidai
• Reporter: Anton Haidai
• Created: 31/Jul/20 09:01
• Updated: 22/Aug/20 18:48
• Resolved: 07/Aug/20 07:56

Description

RelToSqlConverterTest:

 @Test void testSelectNullNoCast() {
  String query = "select \"product_id\", null as dummy from \"product\"";
  final String expected = "SELECT \"product_id\", CAST(NULL AS NULL) AS \"DUMMY\"\n"
      + "FROM \"foodmart\".\"product\"";
  sql(query).ok(expected);
}

the test works fine in 1.23.

result in 1.24:

Unsupported type when convertTypeToSpec: NULL
java.lang.UnsupportedOperationException: Unsupported type when convertTypeToSpec: NULL at org.apache.calcite.sql.type.SqlTypeUtil.convertTypeToSpec(SqlTypeUtil.java:1078) at org.apache.calcite.sql.SqlDialect.getCastSpec(SqlDialect.java:790) at org.apache.calcite.rel.rel2sql.RelToSqlConverter.castNullType(RelToSqlConverter.java:361) at org.apache.calcite.rel.rel2sql.RelToSqlConverter.visit(RelToSqlConverter.java:342) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at org.apache.calcite.util.ReflectUtil$2.invoke(ReflectUtil.java:524) at org.apache.calcite.rel.rel2sql.RelToSqlConverter.dispatch(RelToSqlConverter.java:131)

Please note, that there is an existing test "testSelectNull()", but it tests nulls with a cast, "CAST(NULL AS INT)".

Issue Links

• is duplicated by: CALCITE-4165 RelToSqlConverter fails on literal, untyped nulls
• links to: GitHub Pull Request #2093