[jira] [Created] (BEAM-7610) SELECT COALESCE(...) isn't inferred as non-nullable field

[Gleb Kanterov (JIRA)]

Gleb Kanterov created BEAM-7610:
-----------------------------------

             Summary: SELECT COALESCE(...) isn't inferred as non-nullable field
                 Key: BEAM-7610
                 URL: https://issues.apache.org/jira/browse/BEAM-7610
             Project: Beam
          Issue Type: Bug
          Components: dsl-sql
    Affects Versions: 2.13.0
            Reporter: Gleb Kanterov
            Assignee: Andrew Pilloud


In Calcite, Coalesce is described as:

{code}
ReturnTypes.cascade(ReturnTypes.LEAST_RESTRICTIVE,
            SqlTypeTransforms.LEAST_NULLABLE)
{code}

However, giving non-null constant as an argument doesn't result in a 
non-nullable expression:

{code}
    Schema inputSchema = Schema.of(
        Schema.Field.of("name", Schema.FieldType.STRING.withNullable(true)));

    PCollection<Row> input = p.apply(Create.of(ImmutableList.<Row>of())
        .withCoder(SchemaCoder.of(inputSchema)));

    Schema outputSchema = input
        .apply(SqlTransform.query("SELECT COALESCE(name, 'unknown') as name 
FROM PCOLLECTION"))
        .getSchema();

    assertEquals(
        Schema.builder().addStringField("name").build(),
        outputSchema);
{code}

Not sure if it's a problem in Calcite or Beam SQL.

There are no other functions that can be used to produce a non-nullable field.




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