Using NOLOCK hint

Use NOLOCK hint to avoid block - this is what I have often heard/see in many forums I participate, during local user group events and meeting. I have always advised that its not that good idea to use hints, as it may cause data corruption and blocking. And, anyways, there are many things that you can do to avoid blocking, like:

1. use sp for everything (almost)  
2. try to avoid using cursor
3. transaction shouldn't be too big etc
4. and, use READPAST hint , I will still say, use this only when you don't have choice

But these all comes from the experience from the field and haven't anything concrete to quote as reference point until last night, I was googling something and this blog article from  Dave, on MSDN Blog showed up.  Now, I can quote SQL Server NOLOCK Hint and Other poor ideas as reference to my peers,and friends at local user group, and I am referencing it here for you to read and make a note.  


I hope this helps.


-- Hemantgiri S. Goswami (http://www.sql-server-citation.com/) 

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SQL Server Wait Types in SQL 2008

While working on an assignment of troubleshooting performance issue few month back I have come across a situation where I have to provide good information about the different waittypes and what they do, while researching a good documentation on wait types I have found the most authentic information on PSS Engineer’s blog where Bob Ward has put them nicely. This blog was published in 2009 but its good to keep handy as reference.

Most of the time wait type says us where the bottleneck are, if you wait types like IO_Completion, PAGE IO LATCH, this is indication for disk IO subsystem has some bottleneck. We have to use perfmon counter to verify this and then work around on resolving this issues.

Let me quote some links for the further reading:

http://blogs.msdn.com/b/psssql/archive/2009/11/03/the-sql-server-wait-type-repository.aspx

http://blogs.msdn.com/b/psssql/archive/2009/11/24/doctor-this-sql-server-appears-to-be-sick.aspx

http://support.microsoft.com/kb/822101

http://blogs.msdn.com/b/psssql/archive/2009/07/08/q-a-on-latches-in-the-sql-server-engine.aspx

-- Hemantgiri S. Goswami (http://www.sql-server-citation.com )

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Why rollback is taking much longer time

Have you ever thought what is a reason that makes Rollback time consuming process?
Whenever you kill some spid or rollback transaction it would take 3 or 4 times more time then it has taken to execute that particular batch/transaction!!!! The reason is that the Rollback is single threaded and hence it most likely to take much longer time read complete article here

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DBCC Shrinkfile and DBCC Shrinkdb is taking more time

DBCC Shrinkfile and DBCC Shrinkdb would likely to take more time for SQL Server 2005 then it would take for SQL Server 2000. The question is why it is so!!! I was reading through some articles and find a wonderfull explaination on this, there is additional logic added to compact text/image (LOB datatypes) in SQL Server 2005 and hence it is taking some more time....Read complete article here

Enjoy reading....

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How to create partitioned table and index in SQL Server 2005

I have found good article on how to create partitioned table and index in SQL Server 2005 here is the link of the article http://msdn.microsoft.com/en-us/library/ms345146.aspx

hope this would helps

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should I shrink my database

I have come across to the post "should I shrink my database" many times, this is certainly not recommended unless it is required. When we have ample space on the hard drive let it be in the size it is.

Because what happens is when you shrink it and as time passes by it would required to grow again and this time it again involves your CPU and I/O cycle which would be costly affair; again, herealso there may be counter arguments too but this is what certainly not recommended on other hand it *depneds* on case to case bases.

What we should really do is to investigate the reasons, why it has grown that big (if you feel so) for example
1. Auto growth option,
2. Activities like BCP/Bulk insert,
3. Reindex,
4. defregment of database

Please refer Tibor Karsazi's article here on the same topic http://www.karaszi.com/SQLServer/info_dont_shrink.asp

Hope this would helps.

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Tuning Stored Procedure

Most of the time I come accross the thread wherein user has requested to get started with stored procedure performance tuning , so here are some good reference material for tuning stored procedure and optimize stored procedure for performance
http://www.sql-server-performance.com/tips/stored_procedures_p1.aspx, http://www.sqlservercentral.com/articles/Performance+Tuning+and+Scaling/performancetuningstoredprocedures/2505/ and http://searchsqlserver.techtarget.com/generic/0,295582,sid87_gci1247499,00.html

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