Showing posts with label Code. Show all posts
Showing posts with label Code. Show all posts

Monday, May 14, 2007

Make Your Case Sensitive Searches 1000 Times Faster

I had an case sensitive update query that ran in about 9 minutes. Since it was a case sensitive query it did an index scan not an index seek.
Once I modified my WHERE clause the update took a little less than 3 seconds

Let's get started and see what I did

First create this table

CREATE TABLE #CaseSensitiveSearchTemp (Val CHAR(1))

INSERT #CaseSensitiveSearchTemp VALUES('A')
INSERT #CaseSensitiveSearchTemp VALUES('B')
INSERT #CaseSensitiveSearchTemp VALUES('C')
INSERT #CaseSensitiveSearchTemp VALUES('D')
INSERT #CaseSensitiveSearchTemp VALUES('E')
INSERT #CaseSensitiveSearchTemp VALUES('F')
INSERT #CaseSensitiveSearchTemp VALUES('G')
INSERT #CaseSensitiveSearchTemp VALUES('H')

Now we will insert some lowercase characters

INSERT #CaseSensitiveSearchTemp
SELECT LOWER(Val) FROM #CaseSensitiveSearchTemp

Now we will create our real table which will have 65536 rows

CREATE TABLE CaseSensitiveSearch (Val VARCHAR(50))

We will do a couple of cross joins to generate the data for our queries

INSERT CaseSensitiveSearch
SELECT t1.val + t2.val + t3.val + t4.val
FROM #CaseSensitiveSearchTemp t1
CROSS JOIN #CaseSensitiveSearchTemp t2
CROSS JOIN #CaseSensitiveSearchTemp t3
CROSS JOIN #CaseSensitiveSearchTemp t4


This should give you 65536 rows

SELECT * FROM CaseSensitiveSearch


Create an index on the table

CREATE INDEX IX_SearchVal ON CaseSensitiveSearch(Val)


This is how you do a case sensitive search

SELECT * FROM CaseSensitiveSearch
WHERE Val = 'ABCD' COLLATE SQL_Latin1_General_CP1_CS_AS



Now hit CRLK + K (SQL Server 2000) or CRLK + M(SQL Server 2005)

run these 2 queries in one batch by highlighting them both and hitting F5

SELECT * FROM CaseSensitiveSearch
WHERE Val = 'ABCD' COLLATE SQL_Latin1_General_CP1_CS_AS

SELECT * FROM CaseSensitiveSearch
WHERE Val = 'ABCD' COLLATE SQL_Latin1_General_CP1_CS_AS
AND Val LIKE 'ABCD'

Look at the execution plan, I get 98.71% for the first query and 1.29% for the second query. Just by adding the AND condition SQL server is able to do an index seek and run the query many times faster




Now try it with a lowercase a

SELECT * FROM CaseSensitiveSearch
WHERE Val = 'aBCD' COLLATE SQL_Latin1_General_CP1_CS_AS

SELECT * FROM CaseSensitiveSearch
WHERE Val = 'aBCD' COLLATE SQL_Latin1_General_CP1_CS_AS
AND Val LIKE 'aBCD'


You see it all works without a problem, the correct result is returned

Tuesday, April 10, 2007

Script Multiple Procs With Create And Drop Statements In SQL Server 2005

In SQL Server 2005 Management studio you can not script out multiple procedures with a create and drop statement
This is what you have to do:
1. Open you favorite database in the management studio.
2. Make sure the summary window is visible. (Press F7)
3. In the summary window, double click databases.
4. Double click 'YourDatabase'
5. Double Click 'Programability'
6. Double Click 'Stored Procedures'
7. Select the stored procedures you want to script. (using CTRL/SHIFT clicking).
8. Right click -> Script Stored Procedures As -> Drop -> New Query Editor Window.

Repeat step 8 for the Create.

Who wants to do that? Not me.
Here is a pure T-SQL solution, I didn't feel like using SMO. I can just run this code, copy and paste the output in a new window and I am done.

This code takes care of schema's it also grabs just procedures and only the ones that are created by users (OBJECTPROPERTY 'IsMSShipped' takes care of that)



USE AdventureWorks
GO

SET NOCOUNT ON

CREATE TABLE
#ProcHolder (ID int identity,ProcName VARCHAR(8000), ProcDefinition VARCHAR(MAX))

INSERT #ProcHolder
SELECT QUOTENAME(SPECIFIC_SCHEMA) + '.' + QUOTENAME(SPECIFIC_NAME),OBJECT_DEFINITION(OBJECT_ID(QUOTENAME(SPECIFIC_SCHEMA) + '.' + QUOTENAME(SPECIFIC_NAME)))
FROM INFORMATION_SCHEMA.ROUTINES
WHERE ROUTINE_TYPE = 'PROCEDURE'
AND OBJECTPROPERTY(OBJECT_ID(QUOTENAME(SPECIFIC_SCHEMA) + '.' + QUOTENAME(SPECIFIC_NAME)),'IsMSShipped') = 0
--SELECT * FROM #ProcHolder --if you want to test


DECLARE @LoopID int,@MaxLoopID int,@ProcDefinition VARCHAR(MAX),@ProcName VARCHAR(8000)
SELECT @LoopID =1,@MaxLoopID = MAX(id) FROM #ProcHolder

WHILE @LoopID < @MaxLoopID
BEGIN
SELECT
@ProcDefinition = ProcDefinition,@ProcName =ProcName
FROM #ProcHolder
WHERE id = @LoopID

PRINT 'if exists (select * from dbo.sysobjects where id = OBJECT_ID(N''' + @ProcName + ''') and OBJECTPROPERTY(id, N''IsProcedure'') = 1)'
PRINT 'drop procedure ' + @ProcName
PRINT 'GO'
PRINT ''
PRINT ''

PRINT @ProcDefinition
PRINT 'GO'
PRINT ''
PRINT ''

SET @LoopID = @LoopID +1
END



DROP TABLE #ProcHolder


That is it, let me know what you think

Wednesday, March 14, 2007

How To Get The Database Name For The Current User Process

This question pops up frequent enough so here are 4 ways to return the database name for the current user process

First up is the fastest method. this will run on SQL Server 200 and 2005

SELECT DB_NAME()


Next up is getting the name by joining the sys.dm_exec_requests dmv and sys.sysdatabases. this runs on SQL Server 2005 only

SELECT s.name
FROM sys.dm_exec_requests d
JOIN sys.sysdatabases s on d.database_id = s.dbid
WHERE session_id = @@SPID

Here is something similar, this also runs only on SQL Server 2005

SELECT name
FROM sys.sysdatabases
WHERE dbid = DB_ID()


And we end with something that runs on both SQL Server 2005 and 2000
SELECT name
FROM master..sysdatabases
WHERE dbid = DB_ID()


But like I said before you should always use DB_NAME()