Parameter Sniffing Issues in SSRS

 Parameter sniffing in SQL Server Reporting Services (SSRS) refers to a situation where SQL Server generates an execution plan for a stored procedure or query based on the parameters passed during the first execution and then reuses that plan for subsequent executions. This can lead to performance issues if the initial parameters are not representative of typical workloads. Here are some strategies to mitigate parameter sniffing issues in SSRS:

1. Optimize Stored Procedures and Queries:

   • Use local variables to prevent parameter sniffing by copying input parameters to local variables and using those variables in your queries.

     sql
     CREATE PROCEDURE GetReportData (@Parameter1 INT, @Parameter2 NVARCHAR(50))
     AS
     BEGIN
         DECLARE @LocalParameter1 INT = @Parameter1;
         DECLARE @LocalParameter2 NVARCHAR(50) = @Parameter2;
     
         -- Use local parameters in your queries
         SELECT *
         FROM YourTable
         WHERE Column1 = @LocalParameter1 AND Column2 = @LocalParameter2;
     END

2. OPTION (RECOMPILE):

   • Use the OPTION (RECOMPILE) hint to force SQL Server to recompile the query every time it runs, generating a new execution plan each time.

     sql
     SELECT *
     FROM YourTable
     WHERE Column1 = @Parameter1 AND Column2 = @Parameter2
     OPTION (RECOMPILE);

   • Be cautious with this approach as it can increase CPU usage due to frequent recompilations.

3. Optimize for Unknown:

   • Use the OPTIMIZE FOR UNKNOWN hint to force SQL Server to use average statistical data instead of the initial parameter values.

     sql
     SELECT *
     FROM YourTable
     WHERE Column1 = @Parameter1 AND Column2 = @Parameter2
     OPTION (OPTIMIZE FOR UNKNOWN);

4. Plan Guides:

   • Use plan guides to apply specific query hints or execution plans for your queries without modifying the query text.

5. Indexed Views and Computed Columns:

   • Use indexed views or computed columns to improve query performance, which can mitigate the impact of parameter sniffing.

6. Statistics and Index Maintenance:

   • Regularly update statistics and maintain indexes to ensure SQL Server has accurate data distribution information, which can help in generating efficient execution plans.

7. Forced Parameterization:

   • Enable forced parameterization at the database level to force SQL Server to parameterize all queries. This can reduce the impact of parameter sniffing but may not be suitable for all workloads.

     sql
     
     ALTER DATABASE YourDatabase
     SET PARAMETERIZATION FORCED;
     

8. Query Store:

   • Use the Query Store feature in SQL Server to monitor query performance and identify parameter sniffing issues. You can force specific execution plans for problematic queries.

     sql
     -- Enable Query Store
     ALTER DATABASE YourDatabase
     SET QUERY_STORE = ON;
     
     -- Force a specific execution plan
     EXEC sp_query_store_force_plan @query_id = 1, @plan_id = 1;

9. Report-Specific Solutions:

   • In SSRS, consider using different stored procedures or queries for different report parameter combinations if you know certain parameter sets cause performance issues.
   • Use report parameters to control the logic in your queries or stored procedures to better handle different parameter values.

10. Caching and Snapshots:

    • Use report caching and snapshots in SSRS to reduce the frequency of query executions, which can help mitigate the impact of parameter sniffing.

By employing these strategies, you can mitigate parameter sniffing issues and improve the performance and reliability of your SSRS reports. The choice of strategy depends on the specific context and requirements of your reporting environment.

Implementing error handling and logging within SSRS

 Implementing error handling and logging in SQL Server Reporting Services (SSRS) involves several approaches since SSRS itself does not provide built-in comprehensive error handling or logging mechanisms. Here are some strategies to handle errors and implement logging in SSRS:

1. Using Try-Catch in SQL Queries:

   • Within your SQL queries, use TRY-CATCH blocks to handle exceptions. You can log errors to a table in your database.

   sql
   BEGIN TRY
       -- Your SQL code here
   END TRY
   BEGIN CATCH
       INSERT INTO ErrorLog (ErrorMessage, ErrorSeverity, ErrorState, ErrorLine, ErrorProcedure)
       VALUES (ERROR_MESSAGE(), ERROR_SEVERITY(), ERROR_STATE(), ERROR_LINE(), ERROR_PROCEDURE());
       -- You can also raise the error again if needed
       THROW;
   END CATCH;

2. Custom Code in SSRS Reports:

   • You can write custom code in SSRS reports (using VB.NET) to handle certain errors and log them. Go to the Report Properties and add your custom code under the 'Code' tab.

   vb
   Public Function LogError(ByVal errorMsg As String) As String
       ' Write your custom error logging logic here
       ' For example, write to a file or a database table
       Return errorMsg
   End Function
   

   • Call this function in your report expressions to handle and log errors.

3. SSRS Event Handlers:

   • Use SSRS event handlers in the Report Server to capture and log errors. This involves creating custom extensions or using Report Server event handlers.

4. Using Report Server Execution Logs:

   • SSRS includes execution logs that can be used to monitor and troubleshoot report execution. These logs include information about report execution times, parameters, and errors.
   • Configure and query the ReportServer database’s ExecutionLog3 view to analyze report executions and errors.

   sql
   SELECT *
   FROM ReportServer.dbo.ExecutionLog3
   WHERE Status = 'rsProcessingAborted' OR Status = 'rsRuntimeError'

5. Custom Logging Tables:

   • Create custom logging tables in your database to log report parameters, execution times, and errors manually.

   sql
   CREATE TABLE ReportExecutionLog (
       ReportName NVARCHAR(255),
       ExecutionTime DATETIME,
       Parameters NVARCHAR(MAX),
       ErrorMessage NVARCHAR(MAX),
       Status NVARCHAR(50)
   );
   

   • Insert logs into this table at appropriate places in your reports or stored procedures.

   sql
   INSERT INTO ReportExecutionLog (ReportName, ExecutionTime, Parameters, ErrorMessage, Status)
   VALUES (@ReportName, GETDATE(), @Parameters, @ErrorMessage, @Status);

6. Configuring Report Server Logging Options:

   • Configure the SSRS Report Server to log more detailed information by modifying the RSReportServer.config file. Increase the logging level to capture more detailed information.

   xml
   <Configuration>
       <LogLevel>Verbose</LogLevel>
   </Configuration>

7. Using Subscriptions and Notifications:

   • Set up report subscriptions to send notifications when a report execution fails. This can help in proactive error handling.

By combining these techniques, you can create a robust error handling and logging mechanism for your SSRS reports. Each approach has its specific use cases and can be tailored to meet the needs of your reporting environment.