Why multiple plans for one query are bad?

Why multiple plans for one query are bad?

But if your app is sending in the same query thousands of times, each with different parameters, this can add up to more CPU time, more memory used for caching plans, and less memory used for caching data. You can do EXEC sp_BlitzCache @SortOrder = ‘query hash’ to find the queries to focus on, too.

How do I run a SQL query on multiple instances?

In SQL Server Management Studio, on the View menu, click Registered Servers. Expand a Central Management Server, right-click a server group, point to Connect, and then click New Query. By default, the results pane will combine the query results from all the servers in the server group.

How do you compare two query performances?

To do so, just open the query execution plan in SQL Server Management Studio 2016. Once opened, right click on the execution plan, and click on the Showplan compare.

How can we make stored procedure more efficient?

Improve stored procedure performance in SQL Server

1. Use SET NOCOUNT ON.
2. Use fully qualified procedure name.
3. sp_executesql instead of Execute for dynamic queries.
4. Using IF EXISTS AND SELECT.
5. Avoid naming user stored procedure as sp_procedurename.
6. Use set based queries wherever possible.
7. Keep transaction short and crisp.

Why do I have two plans for the same query?

The first one is Number of pages consumed by the cache object, so you can clearly see that one plan is bigger. The second columns, setopts, is the key one, this is the cause of having two different plans for the same query. Here is BOL description of this column:

When does execution plan change for same query?

Execution plan changes for a query when run on same server but with different parameter value. In one it uses clustered index, which is expected to be used for index seek. But for another value, a non-clustered index is used where Index scan is used,which should not have happened.

How to select plan handle from syscacheobjects?

SELECT * FROM sys.dm_exec_cached_plans PLANS CROSS APPLY sys.dm_exec_sql_text (PLANS.plan_handle) AS Q where [text] like ‘%SOMETHING%’ order by [text] vs select * from syscacheobjects where sql like ‘%SOMETHING%’ order by [sql] This is not true. Your plans are different and you can see it looking at pagesused and setopts columns.

What makes an application different from a SSMS?

There are potentially two factors at play here (which could also be relevant when the comparison is NOT between the application and SSMS): The application almost always has different SET settings than SSMS (these are things like ARITHABORT, ANSI_NULLS and QUOTED_IDENTIFIER ).