SQL Server Denali has a new feature allowing pagination using the order by clause. A common solution needed for the front end is to paginate records prior to sending them to the webserver. More frequently now, we are seeing demormalized data sets being stored in the WebServer’s or a middle tiers cache mechanism. Those solutions however are more difficult to maintain, persist and synchronize. Enter the old fashioned database paging solution. This paging solution initially grabs a subset of a table and counts the records. It then stores ordered results based on the parameter passed into the common table expression. Additional parameters are the number of rows the caller wants on each page and the page number the caller is currently retrieving. [cc lang=”sql”] CREATE PROCEDURE dbo.GetEmployees ( @SortColumn VARCHAR(50) = null, @iRows INT = 10, @iPageNum INT = 1 ) AS BEGIN SET NOCOUNT ON DECLARE @RecordCount int DECLARE @iNbrPages int SET @RecordCount = 0 SET @iNbrPages = 0 SELECT emp.EmployeeID, emp.FirstName, emp.LastName, emp.DateHired INTO #Employees FROM HR.Employees emp WHERE emp.IsTerminated = 1 SELECT @iNbrPages = CEILING(COUNT(1)/(@iRows*1.0)), @RecordCount = COUNT(1) FROM #Employees BEGIN ;WITH PagingCTE ( Row_ID, EmployeeID, FirstName, LastName, DateHired ) AS ( SELECT ROW_NUMBER() OVER(ORDER BY CASE WHEN @SortColumn = ‘EmployeeID’ THEN emp.EmployeeID END ASC, CASE WHEN @SortColumn = ‘FirstName’ THEN emp.FirstName END ASC, CASE WHEN @SortColumn = ‘LastName’ THEN emp.LastName END ASC, CASE WHEN @SortColumn = ‘DateHired’ THEN emp.DateHired END ASC ) AS [Row_ID], emp.EmployeeID, emp.FirstName, emp.LastName, emp.DateHired FROM #Employees emp ) SELECT emp.EmployeeID, emp.FirstName, emp.LastName, […]
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With SQL Server 2005+, it is very easy to view the specifics of connection information. This is very useful because when troubleshooting slowdowns. Luckily there are a few dynamic management views that provide insight into connection and session information. The following query groups the connections according the program that is connected to SQL Server. This information can be spoofed however using a connection string. When running this query, you will find how important it is to add the application name to the query string. The query also shows the number of connections opened by each application. [cc lang=”sql”] — By Application SELECT CPU = SUM(cpu_time) ,WaitTime = SUM(total_scheduled_time) ,ElapsedTime = SUM(total_elapsed_time) ,Reads = SUM(num_reads) ,Writes = SUM(num_writes) ,Connections = COUNT(1) ,Program = program_name FROM sys.dm_exec_connections con LEFT JOIN sys.dm_exec_sessions ses ON ses.session_id = con.session_id GROUP BY program_name ORDER BY cpu DESC [/cc] This next query groups the same information by user: [cc lang=”sql”] — Group By User SELECT CPU = SUM(cpu_time) ,WaitTime = SUM(total_scheduled_time) ,ElapsedTime = SUM(total_elapsed_time) ,Reads = SUM(num_reads) ,Writes = SUM(num_writes) ,Connections = COUNT(1) ,[login] = original_login_name from sys.dm_exec_connections con LEFT JOIN sys.dm_exec_sessions ses ON ses.session_id = con.session_id GROUP BY original_login_name [/cc] By using sp_who3, you can also find the exact statements running, along with more detailed information.
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Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. This error message is due to the server setting of Remote Connection Query Timeout. The default is 600 seconds, or 10 minutes. [cc lang=”sql”] EXEC SP_CONFIGURE ‘remote query timeout’, 1800 reconfigure EXEC sp_configure EXEC SP_CONFIGURE ‘show advanced options’, 1 reconfigure EXEC sp_configure EXEC SP_CONFIGURE ‘remote query timeout’, 1800 reconfigure EXEC sp_configure [/cc] After making this change, make sure to close the window and create a new connection in order to inherit the new query timeout settings.
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One new feature that SQL Server 2008 offers is more reliable dependency information. SQL Server 2005 offered a DMV (dynamic management view) called sys.sql_dependencies. It is now replaced by a more reliable sys.sql_expression_dependencies. The following script will show all the procedures that reference a given table name, along with the columns the procedure references also. Please note, this does not take into account any dynamic SQL. [cc lang=”sql”] USE MYDatabase GO DECLARE @TableName varchar(100) SET @TableName = ‘mytable’ SELECT SourceSchema = OBJECT_SCHEMA_NAME(sed.referencing_id) ,SourceObject = OBJECT_NAME(sed.referencing_id) ,ReferencedDB = ISNULL(sre.referenced_database_name, DB_NAME()) ,ReferencedSchema = ISNULL(sre.referenced_schema_name, OBJECT_SCHEMA_NAME(sed.referencing_id)) ,ReferencedObject = sre.referenced_entity_name ,ReferencedColumnID = sre.referenced_minor_id ,ReferencedColumn = sre.referenced_minor_name FROM sys.sql_expression_dependencies sed CROSS APPLY sys.dm_sql_referenced_entities(OBJECT_SCHEMA_NAME(sed.referencing_id) + ‘.’ + OBJECT_NAME(sed.referencing_id), ‘OBJECT’) sre WHERE sed.referenced_entity_name = @TableName AND sre.referenced_entity_name = @TableName [/cc]
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[cc lang=”sql”] DROP INDEX table_name.index_name [/cc]
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