CREATE TABLE [dbo].[Commits]
([CommitID] [bigint] IDENTITY(1,1) NOT FOR REPLICATION NOT NULL,[AuthorID] [bigint] NOT NULL,[CreatedDate] [datetime2](7) NOT NULL,[CreatedDateKey] [int] NOT NULL,CONSTRAINT [PK__Commits_CommitID] PRIMARY KEY CLUSTERED
([CommitID] ASC,[CreatedDateKey] ASC
)
) 

CREATE view [dbo].[view_commits]
asselect [CommitID],[AuthorID],[CreatedDate],[CreatedDateKey]
from dbo.commits c with(nolock)
where c.[CreatedDateKey] between 20150900 and 20160000union ALL
select [CommitID],[AuthorID],[CreatedDate],[CreatedDateKey]
from db3.tdw.dbo.commits c with(nolock)
where c.[CreatedDateKey] between 20150000 and 20150500union ALL
select [CommitID],[AuthorID],[CreatedDate],[CreatedDateKey]
from db2.tdw.dbo.commits c with(nolock)
where c.[CreatedDateKey] between 20150500 and 20150900
WITH check OPTION;
GO

select sum(t.cnt) as cnt
from
(select count(0) as cntfrom dbo.commits c  with(nolock)where day(c.[CreatedDate])=1UNION allselect p.cntfrom openquery(db2,N'select count(0) as cntfrom dbo.commits c  with(nolock)where day(c.[CreatedDate])=1') as pUNION allselect p.cntfrom openquery(db3,N'select count(0) as cntfrom dbo.commits c  with(nolock)where day(c.[CreatedDate])=1') as p
) as t

static void Main(string[] args)
{List<Task> tasks = new List<Task>();int c1=0, c2=0, c3=0;Task t1 = new Task(()=> {c1= GetCount("xxx");});Task t2 = new Task(() =>{c2=  GetCount("xxx");});Task t3 = new Task(() =>{c3= GetCount("xxx");});tasks.Add(t1);tasks.Add(t2);tasks.Add(t3);Stopwatch sw = new Stopwatch();sw.Start(); t1.Start();t2.Start();t3.Start();Task.WaitAll(tasks.ToArray());int sum = c1 + c2 + c3;sw.Stop();Console.Read();
}static int GetCount(string str)
{using (SqlConnection con = new SqlConnection(str)){con.Open();var cmd = con.CreateCommand();cmd.CommandText = @" select count(0) as cntfrom dbo.commits c  with(nolock)where day(c.[CreatedDate]) = 1";int count = (int)cmd.ExecuteScalar();con.Close();return count;}
}