[jira] [Created] (CALCITE-5649) Produce row count statistics in ReflectiveSchema when trivial

["Adam Kennedy (Jira)" <ji...@apache.org>]

Adam Kennedy created CALCITE-5649:
-------------------------------------

             Summary: Produce row count statistics in ReflectiveSchema when trivial
                 Key: CALCITE-5649
                 URL: https://issues.apache.org/jira/browse/CALCITE-5649
             Project: Calcite
          Issue Type: Improvement
          Components: core
    Affects Versions: 1.34.0
            Reporter: Adam Kennedy


When testing new Calcite implementations it is most simple (and several online examples use) a trivial reflected synthetic schema such as the following:

{code:java}
    public Schema getSchema() {
        return new ReflectiveSchema(new PeopleSchema());
    }

    public static final class PeopleSchema {
        public final Person[] heroes = {
                new Person("Ironman", 12),
                new Person("Batman", 10)
        };

        public static class Person {
            public final String name;
            public final int age;

            public Person(final String name, final int age) {
                this.name = name;
                this.age = age;
            }
        }
    }
{code}

While this works for some basics, the lack of statistics makes it less useful than it could be. While not all variations supported by ReflectiveSchema can easily capture statistics, the variation which provides the table as an array has trivial access to a valid RowCount value.

For these simple cases ReflectiveSchema should provide a Statistic object with a valid row count so the simple synthetic schemas will be more useful.



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