Subquery in view runs slow - sql

Question

Hello i have an issue with my view. The Subquery causes the view to run very slowly.
SELECT dbo.Calls.CallID
,dbo.Calls.StartTime
,dbo.Calls.EndTime
,dbo.Connections.Connectionname
,dbo.Repositorys.RepositoryName
,REPLACE(dbo.Calls.Querytime ,',' ,'.') AS Querytijd
,dbo.Calls.Uur
,dbo.Calls.DayOfMonth
,REPLACE(
(
SELECT MAX(Querytime) AS MaxQueryTime
FROM dbo.Calls AS C
WHERE (
DATEPART(yyyy ,StartTime)=DATEPART(yyyy ,dbo.Calls.StartTime)
)
AND (DATEPART(M ,StartTime)=DATEPART(M,dbo.Calls.StartTime))
AND (DayOfMonth=dbo.Calls.DayOfMonth)
AND (Uur=dbo.Calls.Uur)
AND (
DATEPART(MINUTE ,dbo.Calls.StartTime)=DATEPART(Minute ,StartTime)
)
)
,','
,'.'
) AS MaxQueryTime
FROM dbo.Calls
INNER JOIN dbo.Connections
ON dbo.Calls.ConnectionID = dbo.Connections.ConnectionID
LEFT OUTER JOIN dbo.Repositorys
ON dbo.Connections.RepositoryID = dbo.Repositorys.RepositoryID
I basically want the maximum QueryTime where the year/month/day/hour/minute of the StartTime is the same.

Answer 1

In SQLServer2005+ you can use OVER() clause
SELECT dbo.Calls.CallID,
dbo.Calls.StartTime,
dbo.Calls.EndTime,
dbo.Connections.Connectionname,
dbo.Repositorys.RepositoryName,
REPLACE(dbo.Calls.Querytime, ',', '.') AS Querytijd,
dbo.Calls.Uur,
dbo.Calls.DayOfMonth,
REPLACE(MAX(Querytime) OVER(PARTITION BY DATEPART(yyyy ,StartTime),
DATEPART(Minute ,StartTime),
DayOfMonth, Uur), ',', '.'
) AS MaxQueryTime
FROM dbo.Calls INNER JOIN dbo.Connections
ON dbo.Calls.ConnectionID = dbo.Connections.ConnectionID
LEFT OUTER JOIN dbo.Repositorys
ON dbo.Connections.RepositoryID = dbo.Repositorys.RepositoryID

Answer 2

Is it Query working ?
When i look at your Query "From" keyword are used twice in single Query.
There are join of two tables only. if you want to make your result fast then filter both table first then make join so there will be less number of row in join which will optimize your result.
SELECT dbo.Calls.CallID, dbo.Calls.StartTime, dbo.Calls.EndTime,
dbo.Connections.Connectionname, dbo.Repositorys.RepositoryName,
REPLACE(dbo.Calls.Querytime, ',', '.') AS Querytijd, dbo.Calls.Uur,
dbo.Calls.DayOfMonth, REPLACE((SELECT MAX(Querytime) AS MaxQueryTime
FROM dbo.Calls AS C
WHERE (DATEPART(yyyy, StartTime) = DATEPART(yyyy, dbo.Calls.StartTime))
AND (DayOfMonth = dbo.Calls.DayOfMonth) AND (Uur = dbo.Calls.Uur) AND
(DATEPART(MINUTE, dbo.Calls.StartTime) = DATEPART(Minute, StartTime))), ',', '.') AS MaxQueryTime
FROM dbo.Calls INNER JOIN dbo.Connections ON dbo.Calls.ConnectionID = dbo.Connections.ConnectionID
LEFT OUTER JOIN dbo.Repositorys ON dbo.Connections.RepositoryID = dbo.Repositorys.RepositoryID

Answer 3

SELECT dbo.Calls.CallID
,dbo.Calls.StartTime
,dbo.Calls.EndTime
,dbo.Connections.Connectionname
,dbo.Repositorys.RepositoryName
,REPLACE(dbo.Calls.Querytime ,',' ,'.') AS Querytijd
,dbo.Calls.Uur
,dbo.Calls.DayOfMonth
,REPLACE( QUERYTIME,',','.') AS MaxQueryTime
FROM dbo.Calls
INNER JOIN dbo.Connections
ON dbo.Calls.ConnectionID = dbo.Connections.ConnectionID
LEFT OUTER JOIN dbo.Repositorys
ON dbo.Connections.RepositoryID = dbo.Repositorys.RepositoryID
LEFT JOIN
(
SELECT StartTime, Uur, DayOfMonth, StartTime, MAX(QUERYTIME) AS QUERYTIME
FROM dbo.Calls
GROUP BY StartTime, Uur, DayOfMonth, StartTime
) AS C
ON DATEPART(yyyy ,C.StartTime)=DATEPART(yyyy ,dbo.Calls.StartTime)
AND C.DayOfMonth=dbo.Calls.DayOfMonth
AND C.Uur=dbo.Calls.Uur
AND DATEPART(MINUTE ,dbo.Calls.StartTime)=DATEPART(Minute ,C.StartTime)

Answer 4

When i look at your Query .. you are calculating "MaxQueryTime" for each row. To Optimize this Query you can calculate "MaxQueryTime" once then using union Keyword you can combine to your result set. According to me "MaxQueryTime" will be same for all.
(SELECT REPLACE(MAX(Querytime),',','.') AS MaxQueryTime
FROM dbo.Calls AS C
WHERE (
DATEPART(yyyy ,StartTime)=DATEPART(yyyy ,dbo.Calls.StartTime)
)
AND (DayOfMonth=dbo.Calls.DayOfMonth)
AND (Uur=dbo.Calls.Uur)
AND (
DATEPART(MINUTE ,dbo.Calls.StartTime)=DATEPART(Minute ,StartTime)
)) union all
( SELECT dbo.Calls.CallID
,dbo.Calls.StartTime
,dbo.Calls.EndTime
,dbo.Connections.Connectionname
,dbo.Repositorys.RepositoryName
,REPLACE(dbo.Calls.Querytime ,',' ,'.') AS Querytijd
,dbo.Calls.Uur
,dbo.Calls.DayOfMonth
FROM dbo.Calls
INNER JOIN dbo.Connections
ON dbo.Calls.ConnectionID = dbo.Connections.ConnectionID
LEFT OUTER JOIN dbo.Repositorys
ON dbo.Connections.RepositoryID = dbo.Repositorys.RepositoryID )