Sql option recompile

Today is the last blog post of the year and this is also a final blog post in the series of Parameter Sniffing which I have been writing, sql option recompile. I strongly recommend that you read my earlier blog posts on this topic before you consider the option of recompile suggested in this blog post. Before continuing this blog post, I strongly suggest that you read the following blog posts to get an understanding of the background of the concept sql option recompile I am going to discuss today.

Not sure what parameter sniffing is? Learn from this blog post or this 50 minute free video. You must decide: what hint or command do you use, and where do you put it? What trade-offs are you making when it comes to being able to performance tune your SQL Server in the future? This post runs through common options you have to nudge or whack SQL Server into generating a fresh execution plan. Disclaimer : Recompile hints can kill your performance by lighting your CPUs on fire when used incorrectly.

Sql option recompile

This article intends to give comprehensive details on how we can use the recompilation options of SQL Server stored procedures and how they behave when we use these recompilation options. A stored procedure is a ready T-SQL code that can be reused again and again. The most essential benefits of using stored procedures can be listed as follows:. Performance: After the first execution of the stored procedure, the query optimizer creates an execution plan and this plan is stored in the query plan cache. So that, all next executions of the same SQL Server stored procedure will use this cached stored procedure. This methodology aims to avoid an unnecessary query compilation process. Code reuse: The SQL stored procedure helps to avoid rewriting the same codes again and again. Maintainability: Using stored procedures simplifies code maintenance. Such as, a stored procedure can have wide usage in different applications but only changing the stored procedure will easily affect all applications. Security: SQL stored procedures help us to get rid of dealing with security settings of different database objects.

If certain queries in a procedure regularly use atypical or temporary values, procedure sql option recompile can be improved by using the RECOMPILE query hint inside those queries. Such as, a stored procedure can have wide usage in different applications but only changing the stored procedure will easily affect all applications. Queries that modify table variables do not generate parallel query execution plans.

Here are some problems you can hit with recompile. Not necessarily caused by recompile, but by not re-using plans. Those are very real problems that I see on client systems pretty frequently. But all that assumes that those options are immediately available. You can always yoink it out later.

When an application submits a query to the SQL Server database engine for the first time, a query plan is prepared and complied in order to execute it and then the plan is stored in memory. In subsequent executions of the query, SQL Server will try to re-use this optimized plan from the query plan cache. When SQL Server tries to use this query plan it might find issues or changes that require a recompilation. Due to the recompilation, performance can be impeded. There are a number of reasons why a query recompilation can occur which I will describe in this tip. To better understand recompilations, first we will look at the compilation and caching mechanism that SQL Server uses.

Sql option recompile

Today is the last blog post of the year and this is also a final blog post in the series of Parameter Sniffing which I have been writing. I strongly recommend that you read my earlier blog posts on this topic before you consider the option of recompile suggested in this blog post. Before continuing this blog post, I strongly suggest that you read the following blog posts to get an understanding of the background of the concept which I am going to discuss today.

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This can entail a big hit on server performance as instead of benefiting from cached plans in the buffer, SQL server is now having to reevaluate the query execution plan each time. Actually, it means that the procedure execution plan has been removed from the plan cache. It also occurs if an underlying table referenced by the procedure has undergone physical design changes. Sort of a Band-Aid solution though. When the query needs more resources, it takes more resources and when needed fewer resources, it uses appropriate resources. But if you mark the stored procedure itself for recompilation, it will be reset at the next use. Last Updated on May 16, by Erik Darling. We use sys. This post is a great resource. Consequently, we can use the following methods causing to generate a fresh execution plan for the stored procedures:. For me that has always worked just fine. Otherwise, this can tie up CPU resources. The looped execution with and without recompile does seem like a simpler way to test. Is there a way you could run a query several times, monitoring to see if it got compiled each time? Save Save.

Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. When a procedure is compiled for the first time or recompiled, the procedure's query plan is optimized for the current state of the database and its objects.

So that, all next executions of the same SQL Server stored procedure will use this cached stored procedure. This post is a great resource. You can still get parameter sniffing on any calls to sub-procedures within the stored procedure itself. However, these options cause the creation of a new execution plan. Hey Kevin, Thanks for the feedback. Hi , I need your help to clarify the compilation of SP and Function. The looped execution with and without recompile does seem like a simpler way to test. I highly recommend this resource, and taking advantage of the current discount offering by reviewing their fantastic weekly posting of Office Hours. If you need to identify the impact this procedure is having on your server, you have to run some sort of trace or extended events session and harvest and interpret the results. This example creates the procedure definition. He holds a Masters of Science degree and numerous database certifications. One during peak hours executes between times an hour and the other between times per hour. Sheldon Hull , Post Comment.