ClickHouse/tests/performance/low_cardinality_argument.xml

<test>
    <create_query>
        CREATE TABLE test_lc (x UInt64, lc LowCardinality(Nullable(String))) ENGINE = MergeTree order by x
    </create_query>

    <fill_query>INSERT INTO test_lc SELECT number, number % 10 ? NULL : toString(number % 10000) FROM numbers(1e7)</fill_query>
    
    <query>SELECT isNullable(lc) FROM test_lc FORMAT Null</query>
    <query>SELECT isConstant(lc) FROM test_lc FORMAT Null</query>
    <query>SELECT isNull(lc) FROM test_lc FORMAT Null</query>
    <query>SELECT isNotNull(lc) FROM test_lc FORMAT Null</query>
</test>