datastore/tests/performance/hash_table_iteration_prefetch.xml

<test>
    <settings>
        <max_threads>2</max_threads>
    </settings>
    <create_query>
        create table ht_prefetch (a String, b String, c UInt64) engine=Memory
    </create_query>

    <fill_query>
        insert into ht_prefetch select concat('key', toString(number)), concat('value', toString(rand())), rand() % 1000 from numbers(1e7)
    </fill_query>

    <query>
        select a, b , avg(c) from ht_prefetch group by a, b format Null
    </query>

    <drop_query>
        drop table if exists ht_prefetch
    </drop_query>
</test>