需要帮助来加速SQL Server查询

Question

I have a stored procedure that creates quite a few temp tables in memory. I have the following query which takes an extremely long time to run (7 minutes).

select 
  a.DEPT,
  a.DIV,
  a.PART,
convert(datetime,convert(varchar(2),datepart("mm",a.Release_Date))+'/1/'+ convert(varchar(4),datepart("yyyy",a.Release_Date)),101) as rptng_mnth
from @tmpReportData3 a
where not exists
(select distinct DEPT,DIV,PART from @tmpReportData4 b
where a.DEPT = b.DEPT and a.DIV = b.DIV and a.PART = b.PART)
order by rptng_mnth

Is there a way to speed this up?

Answer 1

This is your query, with the unnecessary select distinct removed from the subquery:

select a.DEPT, a.DIV, a.PART,
       convert(datetime,convert(varchar(2),datepart("mm",a.Release_Date))+'/1/'+ convert(varchar(4),datepart("yyyy",a.Release_Date)),101) as rptng_mnth
from @tmpReportData3 a
where not exists (select DEPT, DIV, PART
                  from @tmpReportData4 b
                  where a.DEPT = b.DEPT and a.DIV = b.DIV and a.PART = b.PART
                 )
order by rptng_mnth;

Your performance problem is probably caused by the not exists . Writing the query using left join might provide some benefit. But, the easiest approach is to switch from using a table variable to a temporary table, #tmpReportData4 . Then add an index on the temporary table: #tmpReportData4(dept, div, part) .

Answer 2

A good start would be to change the "not in" to a left join.

You might also consider using "#" (rather than "@") temp tables, because you can index #-tables.

Can you include the complete stored procedure?

select 
  a.DEPT
 ,a.DIV
 ,a.PART
 ,convert(datetime,convert(varchar(2),datepart("mm",a.Release_Date))+'/1/'+ convert(varchar(4),datepart("yyyy",a.Release_Date)),101) as rptng_mnth
from
  @tmpReportData3 a
  left join @tmpReportData4 b on b.dept = a.dept and a.div = b.div and a.part = b.part
where b.dept is null
order by
  a.rptng_mnth

Answer 3

Try to re-create the sp, but no use any temp table, no use cursors.. that works for me. Also you can post your whole sp code. :)