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Jul 31, 2014 at 07:32 AM

Question about split group by in IQ16 SP08.


Dear all,

I have a customer who encountered performance of "union all view".
As per our analysis, IQ optimizer does't split the Group By.

select "EDPS_CSN","count"()
from "adwown"."vw_adw_dpy111n_01"
group by "edps_csn"

As far as I know, There are some restrictions on the situations and queries that benefit from the split GROUP BY.
But this view meets all restrictions.

Please refer to the below URL.

[Impact on query performance of GROUP BY over a UNION ALL]

So I would like to know the following questions.
1) How to enforce the split the group by.
2) Any changes about split group by in IQ16 SP08?

I failed to attach the query pland becuase it's extension is html.

Any comments or advice will be greatly apprecaited.

** Base Table Rows
1) ADWOWN.TB_ADW_DPY119N : 23,259
2) ADWOWN.TB_ADW_DPY111N : 398,017,348
3) ADWOWN.TB_ADW_DPY117N : 16,160,487


Gi-Sung Jang