Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. This hint name is equivalent to trace flag 4136 or Database Scoped Configuration setting PARAMETER_SNIFFING = OFF. if the plan is stable or you can stabilize it you can execute the sentence with sp_executesql('sql sentence') to save and use a fixed execution plan. The most common use is when you might have a dynamic WHERE clause in a procedureyou wouldn't want that particular query plan to get compiled and saved for subsequent executions because it very well might not be the exact same clause the next time the procedure is called. There are times when procedure recompilation must be forced and other times when it occurs automatically. If you specify more than one join hint, the optimizer selects the least expensive join strategy from the allowed ones. Why did banks give out subprime mortgages leading up to the 2007 financial crisis to begin with? You can use the hint without specifying a hint to override the INDEX table hint behavior you specify in the FROM clause of the query. execution. TRUNCATE, bulk loads, etc. had been passed to the query at all. Allow the optimizer to choose by specifying the NOLOCK hint in the OPTIONS clause. Does staying indoors protect you from wildfire smoke? And to answer your question - yes, I would say it is highly unusual for your best option to be recompiling the execution plan every time you execute the query. Answer (1 of 2): Horrible things. This hint name is equivalent to trace flag 9481 or Database Scoped Configuration setting LEGACY_CARDINALITY_ESTIMATION = ON. Why I am unable to see any electrical conductivity in Permalloy nano powders? hint instead means that a compiled plan can be cached, and performance See Example J. 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. The histogram used to estimate cardinality will be adjusted at query compile time to account for actual maximum or minimum value of this column. thanks, friend. A film where a guy has to convince the robot shes okay. It's not really compiling it like you would with C code. This extended event exposes execution statistics and actual execution plan XML similar to the query_post_execution_showplan extended event but only for queries that contains the new hint. When SQL Server recompiles stored procedures, only the statement that caused the recompilation is compiled, instead of the complete procedure. When a parameter-sensitivity problem is encountered, a common piece of For example, if you pass in a parameter which only retrieves 10 out of 1,000,000 rows, then the query plan created may use a Hash Join, however if the parameter you pass in will use 750,000 of the 1,000,000 rows, the plan created may be an index scan or table scan. On datafeed_trans ( feedid, feedDate) The example uses the AdventureWorks2022 database. Then I was unclear and we agree. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. I understand that the WITH RECOMPILE option forces the optimizer to rebuild the query plan for stored procs but when would you want that to happen? This can happen either because it sniffs the values of the parameters and variables or because it does greater simplifications. This is more powerful than WITH RECOMPILE for two reasons. Connect and share knowledge within a single location that is structured and easy to search. Recompiling a stored procedure with every execution is one of the less efficient ways to combat query plan issues caused by parameterization. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Use the RECOMPILE query hint. A view is expanded when the view definition replaces the view name in the query text. If this option isn't specified, the default limit for the server is 100. The example uses the AdventureWorks2022 database. Azure SQL Database Forces the Query Optimizer to use Cardinality Estimation model that corresponds to the current database compatibility level. This executes the procedure and recompiles the procedure's query plan. If the specified trace flag isn't one that affects a query execution plan, the option will be silently ignored. behaviour, where the entire stored procedure is recompiled on every For a simple SELECT statement, it might not make a difference, but for any non-trivial query, the database is going to spend some serious time (measured in milliseconds, as opposed to the usual microseconds) to come up with an optimal plan. Not the answer you're looking for? As indexes or other changes that affect statistics are made to the database, compiled stored procedures, triggers, and user-defined functions may lose efficiency. Replanning. It should only be used when there are no other options available. For more information, see the Remarks section. Remove option (recompile) from code. For more information, see Scalar UDF Inlining. This option lets you enable a plan-affecting trace flag only during single-query compilation. Don't assume beforehand (without testing) that an SP won't optimize properly. However, then, correlating it to a particular procedure or batch becomes a pain. Forces the Query Optimizer to try a plan that works for the maximum potential row size, possibly at the expense of performance. The PARAMETERIZATION query hint can only be specified inside a plan guide to override the current setting of the PARAMETERIZATION database SET option. execution. Once the query execution plan is generated, specific compilation steps are stored for reuse as an optimization replay script. For more information, see Recompile a Stored Procedure. Often when there is a drastic difference from run to run of a query I find that it is often one of 5 issues. Using WITH RECOMPILE effectively returns us to SQL Server 2000 Also use OPTIMIZE FOR when you create plan guides. To preserve the semantics of the query, the NOLOCK hint is specified in the OPTIONS clause of the plan guide. My understanding from the posts is that OPTION (RECOMPILE) is an expensive operation. SQL Server Query Hint-RECOMPILE on March 22, 2013 The RECOMPILE query hint is a more granular way to force recompilation in a stored procedure to be at the statement level rather than using the WITH RECOMPILE option, which forces the whole stored procedure to be recompiled. @dorfier: hints have there use, and yes they should be used only when absolutely required. Disables Optimized plan forcing for a query. Applies to: SQL Server (starting with SQL Server 2016 (13.x) SP1) and Azure SQL Database. Specifying FORCESEEK with parameters limits the number of plans that can be considered by the Query Optimizer more than when specifying FORCESEEK without parameters. Instructs the query processor not to use a sort operation (batch sort) for optimized nested loop joins when generating a query plan. For more information, see Execution modes. You shouldn't schedule. Pack 1 with Cumulative Update 5), using OPTION (RECOMPILE) has another For recompile this should work ALTER PROCEDURE [dbo]. This helps the query engine to develop a "Plan" of attack for how it will do the query, for example the type of method it will use to match keys between tables using a hash or looking through the entire set. I ceratinly wouldn't recommend using it during testing, when your test data is likely to be unrepresentative of the production environment. In a SQL Server Profiler collection, the event SP:CacheInsert is logged instead of the event SP:Recompile. This instruction makes the query plan independent on the parameter value that was first used when the query was compiled. The values are used only during query optimization, and not during query execution. behaviour, where the entire stored procedure is recompiled on every SQL Server automatically recompiles stored procedures, triggers, and user-defined functions when advantageous. Azure SQL Managed Instance. Specifies all join operations are performed by LOOP JOIN, MERGE JOIN, or HASH JOIN in the whole query. Rows may contain variable-length columns; the Database Engine allows for rows to be defined that have a maximum potential size beyond the ability of the Database Engine to process them. That's when I wish for a good QBE tool. Create MD5 within a pipe without changing the data stream. (SQL Server), what is the difference between sp_executesql and option recompile, Option (recompile) speeds up query execution. What is a SQL stored procedure? My solution to parameter sniffing has always been to hash the parameter values and append "AND {hash} = {hash}" so that the sql was always different for different values. for other statements within the stored procedure are cached and reused Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. Using WITH RECOMPILE also means the compiled plan for the stored This hint name is equivalent to trace flag 2340. Does the word "man" mean "a male friend"? If MAXDOP exceeds the value configured with Resource Governor, the Database Engine uses the Resource Governor MAXDOP value, described in ALTER WORKLOAD GROUP (Transact-SQL). This works well if the values in the rows are static. I didn't mention it in the post because I didn't think it mattered. But also when debugging query performance have a basis for building a hypothesis as to why it is slow or inefficient. Why is that potentially a big deal? It may not be proper to Update Statistics immediately on a Production database as there will be some overhead, slow down and lag depending on the amount of data to sample. information is available in the DMVs (though it is limited to the most Or minimum value of this column Horrible things datafeed_trans ( feedid, feedDate ) the Example uses AdventureWorks2022... Recompile for two reasons the Server is 100 Optimizer to choose by specifying the NOLOCK is! Is equivalent to trace flag 9481 or Database Scoped Configuration setting LEGACY_CARDINALITY_ESTIMATION = on the! Test data is likely to be unrepresentative of the query Optimizer to try plan. First used when there is a drastic difference from run to run of a query I find that is. 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