Stored proc timeout in VB.net but runs quickly in SSMS

Question

I have an issue I hope you can help with.

Developing an vb.net web app, using VS 2013 and SSMS. I have a stored proc which runs very quickly when tested in SSMS. But, when I run an executenonquery in Visual Studio it takes forever, then times out.

What I've tried: To make sure it wasn't a connection related issue, etc... I created a super simple test stored proc with the same input params. The only code change I made was change from "StoredProcSlow" to "StoredProcTest". That's it. This code ran perfectly fine in both SSMS and in Visual Studio. So, I know the vb.net code is fine.

Please note: The Input params of both stored procs (the original and my test) were exactly the same.

I can't try profiler because I'm using an Azure SQL Server database.

Any ideas what could be the problem or how I can troubleshoot further?

UPDATE: I narrowed it down the the UPDATE of a specific table within the stored proc. Even when I do a dummy update, such as "UPDATE dbo.Table1 SET DisplayName = 'XXXXX' WHERE (DisplayName = 'XXXXX')" it still hangs. Disabled all triggers. Still hangs. Any ideas appreciated.

UPDATE 2: I CLONED the offending Table1 into a test table (structure and data). Then I used this new test table in the stored proc. It ran very good. This gets more confusing by the minute!

Answer 1

The reason for significantly different performance is likely different execution plans. Run the query below to see if you have multiple cached plans for the same proc:

SELECT  qs.plan_handle
      , qp.query_plan
FROM    sys.dm_exec_query_stats qs
        CROSS  APPLY sys.dm_exec_sql_text(qs.sql_handle) est
        OUTER APPLY sys.dm_exec_query_plan(qs.plan_handle) AS qp
WHERE   est.objectid = OBJECT_ID('dbo.your_proc');

Multiple plans may exist due to different session settings. The attributes that compose the key are described in the SQL Server Books Online ( https://msdn.microsoft.com/en-us/library/ms189472.aspx ).

For a thorough discussion on this topic, see Erland Sommarskog article: http://www.sommarskog.se/query-plan-mysteries.html . Note that not all the DMVs referenced in the article are available in Azure SQL Database but the basic concepts apply.