Insert Into @temptable hangs but #temptable works

Question

I have a simple temp table declared as a table variable. This is used on nearly 50 deployed databases and works fin. However, on one server, 2008-R2 as are all the others, the Insert statement hangs.  If I change to a #temptable the exact same code
works.  Is there a configuration setting that would account for this behavior.  This is what the code looks like;
On all my other servers this works fine.  On one server it would hang until I modified it to use CREATE table #Counts.
declare @Counts table
CountOf varchar(10), StatusID bigint, StatusName varchar(30), TheCount bigint
insert into @Counts
Select
'Files' as CountOf,
sc.StatusID as StatusID,
sc.StatusName as StatusName,
count_big(*) as TheCount
from
dfFiles f with (nolock)
join dfFolders d with (nolock)
on d.folderid = f.folderid
join dfVolumes v with (nolock)
on v.VolumeUID = d.VolumeUID
and v.MachineName = @MachineName
join dfStatusCodes sc with (nolock)
on sc.StatusID = f.StatusID
group by sc.StatusID, sc.StatusName
union all
Select
'Folders' as CountOf,
sc.StatusID as StatusID,
sc.StatusName as StatusName,
count_big(*) as TheCount
from
dfFolders d with (nolock)
join dfVolumes v with (nolock)
on v.VolumeUID = d.VolumeUID
and v.MachineName = @MachineName
join dfStatusCodes sc with (nolock)
on sc.StatusID = d.StatusID
group by sc.StatusID, sc.StatusName

Answer 1

Supposedly, this is a query-plan issue. As you may know the optimizer works from the statistics sampled from the data and from this it makes an estimation of what is the best plan. Since the data profile may be different in different database, the query
plans may be different in different databases.
And of course, the set of avilable indexes may be different in different databases too.
So what has this do with temp table vs. table variables? The presence of a table variable precludes a parallel plan, whereas there is no such restriction with temp tables.
Thus, you need to look at the query plans to see what is going on. Make sure statistics are up to date, and also check that this server has the same indexes as the other server.
Erland Sommarskog, SQL Server MVP, [email protected]