How to optimize stored procedures? - sql

Question

Following is my Stored Proc.
ALTER PROCEDURE [GetHomePageObjectPageWise]
#PageIndex INT = 1
,#PageSize INT = 10
,#PageCount INT OUTPUT
,#AccountID INT
,#Interests Varchar(3000)
AS
BEGIN
SET NOCOUNT ON;
SELECT StoryID
, AlbumID
, StoryTitle
, CAST(NULL as varchar) AS AlbumName
, (SELECT URL FROM AlbumPictures WHERE (AlbumID = Stories.AlbumID) AND (AlbumCover = 'True')) AS AlbumCover
, Votes
, CAST(NULL as Int) AS PictureId
, 'stories' AS tableName
, (SELECT CASE WHEN EXISTS (
SELECT NestedStories.StoryID FROM NestedStories WHERE (StoryID = Stories.StoryID) AND (AccountID=#AccountID)
)
THEN CAST(1 AS BIT)
ELSE CAST(0 AS BIT) END) AS Flag
, (SELECT UserName FROM UserAccounts WHERE Stories.AccountID=UserAccounts.AccountID) AS Username
INTO #Results1
FROM Stories WHERE FREETEXT(Stories.Tags,#Interests) AND AccountID <> #AccountID AND IsActive='True' AND Abused < 10
I have 7 more SELECT Statements (not included in the question for brevity) in the Stored Proc similar to SELECT StoryID statement, which i UNION ALL like this
SELECT * INTO #Results9 FROM #Results1
UNION ALL
SELECT * FROM #Results2
UNION ALL
SELECT * FROM #Results3
UNION ALL
SELECT * FROM #Results4
UNION ALL
SELECT * FROM #Results5
UNION ALL
SELECT * FROM #Results6
UNION ALL
SELECT * FROM #Results7
UNION ALL
SELECT * FROM #Results8
SELECT ROW_NUMBER() OVER
(
ORDER BY [tableName] DESC
)AS RowNumber
, * INTO #Results
FROM #Results9
DECLARE #RecordCount INT
SELECT #RecordCount = COUNT(*) FROM #Results
SET #PageCount = CEILING(CAST(#RecordCount AS DECIMAL(10, 2)) / CAST(#PageSize AS DECIMAL(10, 2)))
SELECT * FROM #Results
WHERE RowNumber BETWEEN(#PageIndex -1) * #PageSize + 1 AND(((#PageIndex -1) * #PageSize + 1) + #PageSize) - 1
DROP TABLE #Results
DROP TABLE #Results1
DROP TABLE #Results2
DROP TABLE #Results3
DROP TABLE #Results4
END
This takes around 6 seconds to return the result. How can i improve this stored proc? I have very little knowledge about stored procedures.

Answer 1

Raise a nonclustered index on columns in where clause, IsActive, AccountID and Abused.

Answer 2

Well, you can only optimize it by getting rid of the temporary tables. Your approach sucks not because it is a stored procedure (so the SP part is simply totally irrelevant) but because you do a lot of temporary table stuff that forces linear execution and makes it hard for the query optimizer to find a better day to go forward.
In this particular case, it may be that your db design may be horrifically bad (why #result 1 to #result 8 to start with) and then you have tons of "copy into temp table" on every stored procedure.
Query Optimization in SQL works "statement by statement" and execution is never paralleled between statements - so the temp table stuff really gets into your way here. Get rid of the temp tables.

Answer 3

Never ever use directly SELECT * INTO #temp
INSTEAD
Always create #temp tables then INSERT INTO #temp
this will reduce query execution time by 70%
Though it might be frustration to create #temp table with exact structures,
so here is a short cut for that:This will be once performed
CREATE dbo.tableName by using SELECT * INTO tableName from Your calling query
then
sp_help TableName will provide structures.
Then create #temp table in Store Procedure.
I have optimized query for one of our client which was taking 45 minutes to execute, just replaced with this logic It worked !!!
Now it takes 5 Minutes !!