SQL Server 2017 Insert to Temp Table Variable is Very Slow but Not in 2014 - sql-insert

Question

I'm upgrading my test database into 2017 developer edition. Now I have a problem with my table value function. the insert into select performance is very very slow for 4000's insert record.
declare #dateStart date = '4-Jul-2019'
,#dateEnd date = '4-Jul-2019'
declare #ntnOnDate table
(
[NTM ID] char(8)
,[NTM Type] char(3) -- Posible Value: NTM, UPR, SOL
,primary key clustered([NTM ID], [NTM Type])
)
declare #finishedNTM table
(
[NTM ID] char(8)
,[NTM Type] char(3)
,Dept char(3)
,[Model Number] char(4)
,[Shoes Type] int
,[Shoes Version] int
,[Size] varchar(5)
,[Pairs] int not null
--, primary key clustered ([NTM ID], [NTM Type],Dept, [Model Number], [Shoes Type], [Shoes Version], [Size])
)
insert into #ntnOnDate
--- select statement (Only 16 record) --
insert into #finishedNTM (
[NTM ID]
, [NTM Type]
, Dept
, [Model Number]
, [Shoes Type]
, [Shoes Version]
, [Size]
, pairs
)
select
a.[TSW ID] as [NTM ID]
,'NTM' as [NTM Type]
,a.[From Department] as [Dept]
,b.[Model Number]
,b.[Shoes Type]
,b.[Shoes Version]
,b.Size
,sum(b.Pairs) as Pairs
from [TSW Master] a
inner join [TSW Details] b
on a.[TSW ID] = b.[TSW ID]
and a.Issue = b.Issue
and a.[From Department] = b.[From Department]
and a.[To Department] = b.[To Department]
--inner join #ntnOnDate c
-- on a.[TSW ID] = c.[NTM ID]
where a.Executed = 1
and a.Accepted = 1
and a.[From Department] <> '210'
--and c.[NTM Type] = 'NTM'
and a.[TSW ID] in (select x.[NTM ID] from #ntnOnDate x where x.[NTM Type] = 'NTM')
group by
a.[TSW ID]
,a.[From Department]
,b.[Model Number]
,b.[Shoes Type]
,b.[Shoes Version]
,b.Size
The strange thing is when I use "select top 4462" (The record count by the select statement is 4462) with the select statement, the insert will complete in 2 seconds.
Can someone help me? Thanks in advance.
A'an

Answer 1

I found myself a sollution to tweak the insert performance. I Change the insert statement into :
insert #finishedNTM
select
a.[NTM ID]
,'NTM' as [NTM Type]
,b.[From Department] as [Dept]
,b.[Model Number]
,b.[Shoes Type]
,b.[Shoes Version]
,b.Size
,b.Pairs
from #ntnOnDate a
inner join (
select
a.[TSW ID]
,a.[From Department]
,b.[Model Number]
,b.[Shoes Type]
,b.[Shoes Version]
,b.Size
,sum(b.Pairs) as Pairs
from [TSW Master] a
inner join [TSW Details] b
on a.[TSW ID] = b.[TSW ID]
and a.Issue = b.Issue
and a.[From Department] = b.[From Department]
and a.[To Department] = b.[To Department]
where a.Executed = 1
and a.Accepted = 1
and a.[From Department] <> '210'
group by
a.[TSW ID]
,a.[From Department]
,b.[Model Number]
,b.[Shoes Type]
,b.[Shoes Version]
,b.Size
) b
on a.[NTM ID] = b.[TSW ID]
where a.[NTM Type] = 'NTM'
The SUM agregate is moved inside a statement block than I join the block with the other temporary table.
But I still don't know why this problem happened. The query is fine on SQL Server 2014.
Regards
A'an