both have group by, here is sql
select product_sk,sum(1) as recordcount from f_activity group by product_sk
query:0.516 seconds
select substring(fact_bk,1,1) as aa,sum(1) as recordcount from f_activity group by aa query:38.657 seconds
2012/7/27 Stefan Manegold Stefan.Manegold@cwi.nl
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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