Hi all:
<div>    we are testing monetdb on a sql</div><div><br></div><div>select substring(fact_bk,1,1) as aa,sum(1) as recordcount from f_activity group by aa</div><div>the table f_activity have about 5 million rows.  when i run this sql, monetdb need about 30 seconds .  (if we use another no calculated column, it need only 1-3 seconds)</div>
<div>when I run this sql on sql server, it needs only 7 seconds.</div><div><br></div><div>is monetdb not good at calculated column? or we have made some mistake?</div><div><br></div><div>please tell me the reason, thank you.</div>
<div><br></div><div><br></div><div>lixiaohua</div><div>Shanghai,China</div><div><br></div><div><br></div>