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MIGRATION 2005 => 2008 => but now web site is too slow !

  • November 10, 2011 at 8:43 am

    #245930

    Hi,

    We worked with sql server 2005 and since last week end we have migrate all your server, database and so on to sql server 2008.

    Now, we notice since this monday morning that our web site is very slow..

    we don't find a solution and i try to post a message perhpas some people have some idea ..

    Thanks for your time explication ..

    have a nice day

    Christophe

  • November 10, 2011 at 9:30 am

    #1405871

    christophe.bernard 47659 (11/10/2011)

    Hi,

    We worked with sql server 2005 and since last week end we have migrate all your server, database and so on to sql server 2008.

    Now, we notice since this monday morning that our web site is very slow..

    we don't find a solution and i try to post a message perhpas some people have some idea ..

    Thanks for your time explication ..

    have a nice day

    Christophe

    Imagine you are someone trying to answer the question you have posed... what information might you want in order to help the questioner? ... sorry, this is my snarky way of saying "we dont have enough information to help you".

    Is it your website that is slow, or is your sql server performing poorly? how do you know? what have you already looked at? are there some particularly poorly performing queries?

  • November 10, 2011 at 9:38 am

    #1405880

    Did you rebuild all indexes and update all stats with fullscan during the upgrade?

  • November 10, 2011 at 9:39 am

    #1405882

    While we debug this, you can always find the slow queries and try to tune them

    http://www.simple-talk.com/sql/performance/finding-the-causes-of-poor-performance-in-sql-server,-part-1

    http://www.simple-talk.com/sql/performance/finding-the-causes-of-poor-performance-in-sql-server,-part-2

  • November 18, 2011 at 2:38 am

    #1409744

    Hi all,

    thanks for you information, time and so on ..

    I know since my information about our problems wasn't terrible but i'm a beginner and i try to help my team for to find some solution ..

    we have found our problem ..

    in sql server 2008 and perhpas some others version there is a parameters name parameter sniffing it was enabled and with this parameters all stored procedure take more time

    often some procedure who was as this :

    @declare @myString varchar(max)

    @myString = 'SELECT ...'

    exec @myString

    Thanks for all

    Christophe

  • November 18, 2011 at 2:43 am

    #1409750

    SQL Server tries to optimize the execution of your stored procedures by creating compiled execution plans. An execution plan for a stored procedure is created the first time a stored procedure is executed. When the SQL Server database engine compiles a stored procedure it looks at the parameter values being passed and creates an execution plan based on these parameters. The process of looking at parameter values when compiling a stored procedure is commonly called “parameter sniffing”. Parameter sniffing can lead to inefficient execution plans sometimes; especially when a stored procedure is called with parameter values that have different cardinality.

  • November 18, 2011 at 2:50 am

    #1409752

    @declare @myString varchar(max)

    @myString = 'SELECT ...'

    exec @myString

    The above piece of code is Dynamic Query (not very efficient). With this, you are also at a risk of SQL injection.

  • November 18, 2011 at 3:12 am

    #1409760

    hi,

    yes we know but some query take more 40 parameters ..

    i think my team must to take some time for to review dynamic query ..

    thanks

    christophe

  • November 18, 2011 at 3:24 am

    #1409764

    Not sure if it's relevant

    Have you run DBCC Update usage?

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