Export All Plans From Cache to a .SQLPLAN File

PowerShell
I was asked if there was an easy way to export all the plans from cache to a .SQLPLAN file. My immediate answer was, "I'm sure there's a PowerShell script out there somewhere." However, rather than do a Gingle search, I figured I'd quickly knock up an example. The Script I've gone minimal on the script. I'm creating a connection to the local instance, defining a command, and returning the data into a data set. From there, since the data set consists of a single column, I'm walking through them all to export out to a file: $Query = 'SELECT deqp.query_plan FROM sys.dm_exec_query_stats AS deqs CROSS APPLY sys.dm_exec_query_plan(deqs.plan_handle) AS deqp WHERE deqp.query_plan IS NOT NULL;' $SqlConnection = New-Object System.Data.SqlClient.SqlConnection $SqlConnection.ConnectionString = 'Server=ServerX\DOJO;Database=master;trusted_connection=true' $PlanQuery = new-object System.Data.SqlClient.SqlCommand $PlanQuery.CommandText = $Query $PlanQuery.Connection…
Read More

Saving Execution Plans on Azure SQL Database

Azure
In my previous post showing how to get to execution plans in the Database Management Portal, I showed that it's pretty easy to put a query in a query window and get the execution plan. This allows you to understand query behavior in order to tune your T-SQL or your data structures, all through the Azure interface. But, what happens if you want to share an execution plan with a friend, post it to an online forum, save it for later comparisons as part of troubleshooting bad parameter sniffing, track behaviors over time as statistics change, other purposes that I can't think of at the moment? To first answer this question, let me tell you how you would do these things in SQL Server Management Studio (SSMS). First, and most…
Read More

Avoiding Bad Query Performance

TSQL
There’s a very old saying, “When you find yourself in a hole, stop digging.” And my evidence today is: That’s certainly not the hairiest execution plan I’ve seen. In some ways, it’s not all that horrible. But it sure is evidence that someone was down in a hole and they were working that shovel hard. If you’re interested, most of the operators are scans against a table variable that’s 11 million rows deep. There are also table spools chugging away in there. And the select statement only returns 1500 rows. Please, stop digging.
Read More

Expert? Ha!

SQL Server 2005, SQL Server 2008, TSQL
How do you define an expert? My personal definition: An expert is the person that is a chapter ahead of you in the book. Why am I talking about this? Just that I’m feeling more stupid than usual lately. In the last two weeks I’ve had people bring up through various discussions, documents, what have you, four different SQL Server trace flags that will affect how SQL Server builds execution plans and I’ve never heard of any of them before. I’ve never, ever, thought of myself as an expert in execution plans, despite having written a book about them. I just thought I had a good grasp on how they worked and I was willing to share. I didn’t know everything and never pretended to, but I thought I knew…
Read More

Procedure Cache and Dynamic Management Views

SQL Server 2005, SQL Server 2008, TSQL
I'm just going through the chapter on the procedure cache in the new book and I'm having a blast playing with the dynamic management views and functions that let you access the procedure cache. It's just too much fun and way too easy to get detailed information about the queries in the system, not like the old days. First, you can access the cache itself with the DMV, sys.dm_exec_cached_plans. This shows some of the data describing the plan in cache, but most importantly it provides the plan_handle. You need this for other joins later. You can also use sys.dm_exec_query_stats to get aggregated performance statistics about the plan. It also has the plan_handle and two things new to SQL Server 2008, the query_hash and the query_plan_hash, also known as query fingerprints.…
Read More

Query Fingerprints and Plan Fingerprints

nHibernate, SQL Server 2008, TSQL
SQL Server 2008 has been released, but the full capabilities of the product are still be discovered. This isn't a case of discovery so much as Microsoft, in the person of Bart Duncan, has shown us something new. Read the article. This is one of the most exciting things I've seen in a long time. It's especially exciting as we see databases becoming less and less manageable through the implementation of tools like nHibernate. As I noted in a previous post, nHibernate will create a lot of execution plans. With the capabilities here, we'll be able to easily and quickly aggregate some of those plans to identify the costly queries coming out of nHibernate without having to resort to 24 hour Profiler monitoring. Great stuff.
Read More