Sql server option recompile
SQL SERVER OPTION RECOMPILE SOFTWARE
SQL SERVER OPTION RECOMPILE CODE
SQL SERVER OPTION RECOMPILE FREE
I’m also available for consulting if you just don’t have time for that and need to solve performance problems quickly. I’m offering a 75% discount on to my blog readers if you click from here. If this is the kind of SQL Server stuff you love learning about, you’ll love my training. I’m not mad.Īnd yeah, there’s advances in SQL Server 20 that start to address some issues here, but they’re still imperfect. Using a plan guide doesn’t interfere with that precious vendor IP that makes SQL Server unresponsive every 15 minutes.
Plan Guides: An often overlooked detail of plan guides is that you can attach hints to them, including recompile.
You can single out troublesome queries to remove specific plans.
DBCC FREEPROCCACHE: No, not the whole cache.
Sure, you might be able to sneak a recompile hint somewhere in the mix even if it’d make the vendor upset.
SQL SERVER OPTION RECOMPILE SOFTWARE
For third party vendors who have somehow developed software that uses SQL Server for decades without running into a single best practice even by accident, it’s often harder to get those changes through. And yeah, sometimes there’s a good tuning option for these, like changing or adding an index, moving parts of the query around, sticking part of the query in a temp table, etc.īut all that assumes that those options are immediately available. Those are very real problems that I see on client systems pretty frequently.
SQL SERVER OPTION RECOMPILE CODE
CPU spikes for high-frequency execution queries: Maybe time for caching some stuff, or getting away from the kind of code that executes like this (scalar functions, cursors, etc.)īut for everything in the middle: a little RECOMPILE probably won’t hurt that bad.Sucks less if you have a monitoring tool or Query Store. No plan history in the cache (only the most recent plan): Sucks if you’re looking at the plan cache.Long compile times: Admittedly pretty rare, and plan guides or forced plans are likely a better option.Not necessarily caused by recompile, but by not re-using plans. Here are some problems you can hit with recompile. But as I list them out, I’m kinda shrugging. Obviously, you can run into problems if you (“you” includes Entity Framework, AKA the Database Demolisher) author the kind of queries that take a very long time to compile. And if you put it up against the performance problems that you can hit with parameter sniffing, I’d have a hard time telling someone strapped for time and knowledge that it’s the worst idea for them. You can do it in SSMS as well, but Plan Explorer is much nicer.It’s been a while since SQL Server has had a real RECOMPILE problem. Look at details of each operator in the plan and you should see what is going on.
SQL SERVER OPTION RECOMPILE FREE
I would recommend to look at both actual execution plans in the free SQL Sentry Plan Explorer tool. Without OPTION(RECOMPILE) optimiser has to generate a plan that is valid (produces correct results) for any possible value of the parameter.Īs you have observed, this may lead to different plans. If there are a lot of values in the table that are equal to 1, it would choose a scan. If there is only one value in the table that is equal to 1, most likely it will choose a seek. Also, optimiser knows statistics of the table and usually can make a better decision. It does not have to be valid for any other value of the parameter. The generated plan has to be valid for this specific value of the parameter. With OPTION(RECOMPILE) optimiser knows the value of the variable and essentially generates the plan, as if you wrote: SELECT * And simple (7 rows) and actual statistics. With OPTION (RECOMPILE) it uses the key lookup for the D table, without it uses scan for D table. INSERT INTO D (idH, detail) VALUES 'nonononono') INSERT INTO H (header) VALUES ('nonononono') The script is: Create two tables: CREATE TABLE H (id INT PRIMARY KEY CLUSTERED IDENTITY(1,1), header CHAR(100))ĬREATE TABLE D (id INT PRIMARY KEY CLUSTERED IDENTITY(1,1), idH INT, detail CHAR(100)) I am lost why execution plan is different if I run query with option recompile to compare to same query (with clean proc cache) without option recompile.



















