ClickHouse/tests/performance/trim_whitespace.xml

<test>

    <create_query>
        create table if not exists whitespaces
        engine = MergeTree() partition by tuple() order by tuple()
        as
            with 32 - log2(intHash32(number)) + 1 as num_spaces,
                repeat(' ', toUInt32(num_spaces)) as spaces
            select spaces || toString(number) || spaces value
            from numbers_mt(100000000);
    </create_query>



    <substitutions>
        <substitution>
           <name>func</name>
           <values>
               <value>trimLeft(value)</value>
               <value>trimRight(value)</value>
               <value>trimBoth(value)</value>
           </values>
       </substitution>
       <substitution>
           <name>func_slow</name>
           <values>
               <value>replaceRegexpOne(value, '^ *', '')</value>
               <value>replaceRegexpOne(value, ' *$', '')</value>
               <value>replaceRegexpAll(value, '^ *| *$', '')</value>
           </values>
       </substitution>
    </substitutions>

    <query>SELECT {func} FROM whitespaces FORMAT Null</query>
    <query>SELECT {func_slow} FROM whitespaces LIMIT 10000000 FORMAT Null</query>

    <drop_query>DROP TABLE IF EXISTS whitespaces</drop_query>
</test>