Re: Help me in reducing the CPU cost for the high cost query below, as it is hitting production seriously!!

pavan95 wrote
> Hi all,
>
> Hope my mail finds you in good time. I had a problem with a query which is
> hitting the production seriously.
> The below is the sub part of the query for which I cannot reduce the CPU
> cost.
>
> Please check and verify whether I'm doing wrong or whether that type index
> type suits it or not.
>
> Kindly help me resolve this issue.
>
> *Query*:
>
> explain select sum(CASE
> WHEN MOD(cast(effort_hours as decimal),1) =
> 0.45 THEN
> cast(effort_hours as int)+0.75
> ELSE
> CASE
> WHEN MOD(cast(effort_hours as decimal),1)
> =
> 0.15 THEN
> cast(effort_hours as int) + 0.25
>
> ELSE
> CASE
> WHEN MOD(cast(effort_hours as decimal),1)
> =
> 0.30 THEN
> cast(effort_hours as int) + 0.5
>
> ELSE
> CASE
> WHEN MOD(cast(effort_hours as decimal),1)
> =
> 0 THEN
> cast(effort_hours as int)
> end
> END
> END
> END) from tms_timesheet_details,
> tms_wsr_header
> header where wsr_header_id=header.id and work_order_no != 'CORPORATE';
>
>
>
> --
> Sent from:
> http://www.postgresql-archive.org/PostgreSQL-performance-f2050081.html

To start with you can try re-writing this so that it only does the mod cast
once. e.g:
sum (
CASE MOD(cast(effort_hours as decimal),1)
WHEN 0.45 THEN cast(effort_hours as int)+0.75
WHEN 0.15 THEN cast(effort_hours as int)+0.25
WHEN 0.30 THEN cast(effort_hours as int)+0.5
WHEN 0 THEN cast(effort_hours as int)
END
)

--
Sent from: http://www.postgresql-archive.org/PostgreSQL-performance-f2050081.html