MYSQL:

counting 20000 question_attempts, 60000 question_attempt_steps and 180000 question_attempt_step_data
 
    IN (unrelated) execution took 0.54368996620178 seconds
    179820 question_attempt_step_data remaining
 
    EQUAL (related) execution took 0.5357780456543 seconds
    179640 question_attempt_step_data remaining
 
    EXISTS (related) execution took 0.49872303009033 seconds
    179460 question_attempt_step_data remaining
 
    FROM JOIN execution took 0.0028629302978516 seconds
    179280 question_attempt_step_data remaining
 
    FROM USING execution took 0.0026040077209473 seconds
    179100 question_attempt_step_data remaining


counting 100000 question_attempts, 300000 question_attempt_steps and 900000 question_attempt_step_data
 
    IN (unrelated) execution took 3.0166909694672 seconds
    899820 question_attempt_step_data remaining
 
    EQUAL (related) execution took 2.7955451011658 seconds
    899640 question_attempt_step_data remaining
 
    EXISTS (related) execution took 2.5789709091187 seconds
    899460 question_attempt_step_data remaining
 
    FROM JOIN execution took 0.0029830932617188 seconds
    899280 question_attempt_step_data remaining
 
    FROM USING execution took 0.002744197845459 seconds
    899100 question_attempt_step_data remaining


counting 500000 question_attempts, 1500000 question_attempt_steps and 4500000 question_attempt_step_data
 
    IN (unrelated) execution took 15.427474021912 seconds
    4499820 question_attempt_step_data remaining
 
    EQUAL (related) execution took 15.782146930695 seconds
    4499640 question_attempt_step_data remaining
 
    EXISTS (related) execution took 14.763441085815 seconds
    4499460 question_attempt_step_data remaining
 
    FROM JOIN execution took 0.0038988590240479 seconds
    4499280 question_attempt_step_data remaining
 
    FROM USING execution took 0.0034580230712891 seconds
    4499100 question_attempt_step_data remaining



POSTGRESQL:

counting 100000 question_attempts, 300000 question_attempt_steps and 900000 question_attempt_step_data
 
    IN (unrelated) execution took 0.0032730102539062 seconds
    899820 question_attempt_step_data remaining
 
    EQUAL (related) execution took 3.3927338123322 seconds
    899640 question_attempt_step_data remaining
 
    EXISTS (related) execution took 0.002051830291748 seconds
    899460 question_attempt_step_data remaining
 
    FROM USING execution took 0.0020790100097656 seconds
    899280 question_attempt_step_data remaining



MSSQL:

counting 100000 question_attempts, 300000 question_attempt_steps and 900000 question_attempt_step_data
 
    IN (unrelated) execution took 2.6794860363007 seconds
    899820 question_attempt_step_data remaining
 
    EQUAL (related) execution took 5.0533430576324 seconds
    899640 question_attempt_step_data remaining
 
    EXISTS (related) execution took 0.015043973922729 seconds
    899460 question_attempt_step_data remaining
 
    FROM JOIN execution took 0.016202926635742 seconds
    899280 question_attempt_step_data remaining



ORACLE:

counting 100000 question_attempts, 300000 question_attempt_steps and 900000 question_attempt_step_data
 
    IN (unrelated) execution took 1.5360279083252 seconds
    899820 question_attempt_step_data remaining
 
    EQUAL (related) execution took 4.0022511482239 seconds
    899640 question_attempt_step_data remaining
 
    EXISTS (related) execution took 0.31714200973511 seconds
    899460 question_attempt_step_data remaining