What is parameter sniffing issue?
SQL Server creates an optimal plan for a stored procedure by using the parameters that are passed the first time to the stored procedure is executed is called Parameter Sniffing.
How do you fix parameter sniffing?
Workarounds for SQL Server Parameter Sniffing
- Create SQL Server Stored Procedures using the WITH RECOMPILE Option.
- Use the SQL Server Hint OPTION (RECOMPILE)
- Use the SQL Server Hint OPTION (OPTIMIZE FOR)
- Use Dummy Variables on SQL Server Stored Procedures.
- Disable SQL Server Parameter Sniffing at the Instance Level.
Should I disable parameter sniffing?
If you only have equality searches, not range searches, you could probably disable parameter sniffing at the database level and do okay. If you’ve got range searches, though, Parameter Blindfolding is going to backfire, and you’re still going to have a lot of query tuning to do.
How do I disable SQL Server parameter sniffing at the instance level?
Parameter sniffing is enabled by default in SQL Server, you can disable it by turning on the Trace Flag 4136 at the instance level, which will affects all databases hosted in the same instance that may not be acceptable for instance with many databases serving different workload types.
What are SQL parameters?
Parameters are used to exchange data between stored procedures and functions and the application or tool that called the stored procedure or function: Input parameters allow the caller to pass a data value to the stored procedure or function.
How can I improve my SP performance?
Improve stored procedure performance in SQL Server
- Use SET NOCOUNT ON.
- Use fully qualified procedure name.
- sp_executesql instead of Execute for dynamic queries.
- Using IF EXISTS AND SELECT.
- Avoid naming user stored procedure as sp_procedurename.
- Use set based queries wherever possible.
- Keep transaction short and crisp.
How do I recompile SP in SQL Server?
To recompile a stored procedure by using sp_recompile Select New Query, then copy and paste the following example into the query window and click Execute. This does not execute the procedure but it does mark the procedure to be recompiled so that its query plan is updated the next time that the procedure is executed.
What are parameters in a database?
How define parameter in SQL query?
Parameters must be defined with a data type when they are declared in a CREATE PROCEDURE statement. The data type of a parameter determines the type and range of values that are accepted for the parameter when the procedure is called.
How can improve SP performance in SQL Server?
- Specify column names instead of using * in SELECT statement. Try to avoid *
- Avoid temp temporary table. Temporary tables usually increase a query’s complexity.
- Create Proper Index. Proper indexing will improve the speed of the operations in the database.
- Use Join query instead of sub-query and co-related subquery.
How can I speed up my database?
Tips to Increase Database Performance
- Tip 1: Optimize Queries.
- Tip 2: Improve Indexes.
- Tip 3: Defragment Data.
- Tip 4: Increase Memory.
- Tip 5: Strengthen CPU.
- Tip 6: Review Access.
- SolarWinds Database Performance Analyzer (DPA)
- SolarWinds Database Performance Monitor (DPM)
What happens when you recompile a stored procedure?
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. If a database undergoes significant changes to its data or structure, recompiling a procedure updates and optimizes the procedure’s query plan for those changes.
What does it mean to recompile?
Definition of ‘recompile’ 1. to compile (a list, text, etc) again or in a different way. Computing. to compile (a set of machine instructions) again or in a different way.
Why does parameter sniffing cause performance problems?
When a performance problem due to parameter sniffing occurs frequently, it is more likely the result of design and architecture decisions than a query optimizer quirk. When implementing hints, trace flags, or other targeted solutions, be sure they are durable enough to withstand the test of time.
What are some creative approaches to parameter sniffing?
One creative approach towards parameter sniffing is to create a temporary stored procedure that encapsulates the unstable database logic. The temporary proc can be executed as needed and dropped when complete. This isolates execution patterns and limits the lifespan of its execution plan in the cache.
What is suboptimal parameter sniffing?
Suboptimal parameter sniffing is often seen as an anomaly. The optimizer makes bad choices or solar flares somehow intersect with your query’s execution or some other bad thing happens that warrants quick & reckless actions on our part.
What is parameter sniffing game of chance?
This is a game of chance in which a low probability event (parameter sniffing) is crossed with a high probability event (a poor estimate happening to be good enough) to generate a reasonable illusion of a fix. To demo this behavior, we’ll redeclare a parameter locally in our stored procedure from earlier: