Hi,
does without substring() also mean without group by?
(Since you group on the substring())
In other words, what is the exact query you run without substring that takes
1-3 seconds?
And:
Could you run both queries prefixed with TRACE and share the profiling
output?
Stefan
> ------------------------------------------------------------------------------
On Fri, Jul 27, 2012 at 08:41:43AM +0800, li, xiaohua wrote:
> Hi all:
> we are testing monetdb on a sql
>
> select substring(fact_bk,1,1) as aa,sum(1) as recordcount from f_activity
> group by aa
> 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)
> when I run this sql on sql server, it needs only 7 seconds.
>
> is monetdb not good at calculated column? or we have made some mistake?
>
> please tell me the reason, thank you.
>
>
> lixiaohua
> Shanghai,China
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