dd dent - Page 64 - Developer IT

Script to UPDATE STATISTICS with time window

- by Bill Graziano

I recently spent some time troubleshooting odd query plans and came to the conclusion that we needed better statistics. We’ve been running sp_updatestats but apparently it wasn’t sampling enough of the table to get us what we needed. I have a pretty limited window at night where I can hammer the disks while this runs. The script below just calls UPDATE STATITICS on all tables that “need” updating. It defines need as any table whose statistics are older than the number of days you specify (30 by default). It also has a throttle so it breaks out of the loop after a set amount of time (60 minutes). That means it won’t start processing a new table after this time but it might take longer than this to finish what it’s doing. It always processes the oldest statistics first so it will eventually get to all of them. It defaults to sample 25% of the table. I’m not sure that’s a good default but it works for now. I’ve tested this in SQL Server 2005 and SQL Server 2008. I liked the way Michelle parameterized her re-index script and I took the same approach. CREATE PROCEDURE dbo.UpdateStatistics ( @timeLimit smallint = 60 ,@debug bit = 0 ,@executeSQL bit = 1 ,@samplePercent tinyint = 25 ,@printSQL bit = 1 ,@minDays tinyint = 30 )AS/******************************************************************* Copyright Bill Graziano 2010*******************************************************************/SET NOCOUNT ON;PRINT '[ ' + CAST(GETDATE() AS VARCHAR(100)) + ' ] ' + 'Launching...'IF OBJECT_ID('tempdb..#status') IS NOT NULL DROP TABLE #status;CREATE TABLE #status( databaseID INT , databaseName NVARCHAR(128) , objectID INT , page_count INT , schemaName NVARCHAR(128) Null , objectName NVARCHAR(128) Null , lastUpdateDate DATETIME , scanDate DATETIME CONSTRAINT PK_status_tmp PRIMARY KEY CLUSTERED(databaseID, objectID));DECLARE @SQL NVARCHAR(MAX);DECLARE @dbName nvarchar(128);DECLARE @databaseID INT;DECLARE @objectID INT;DECLARE @schemaName NVARCHAR(128);DECLARE @objectName NVARCHAR(128);DECLARE @lastUpdateDate DATETIME;DECLARE @startTime DATETIME;SELECT @startTime = GETDATE();DECLARE cDB CURSORREAD_ONLYFOR select [name] from master.sys.databases where database_id > 4OPEN cDBFETCH NEXT FROM cDB INTO @dbNameWHILE (@@fetch_status <> -1)BEGIN IF (@@fetch_status <> -2) BEGIN SELECT @SQL = ' use ' + QUOTENAME(@dbName) + ' select DB_ID() as databaseID , DB_NAME() as databaseName ,t.object_id ,sum(used_page_count) as page_count ,s.[name] as schemaName ,t.[name] AS objectName , COALESCE(d.stats_date, ''1900-01-01'') , GETDATE() as scanDate from sys.dm_db_partition_stats ps join sys.tables t on t.object_id = ps.object_id join sys.schemas s on s.schema_id = t.schema_id join ( SELECT object_id, MIN(stats_date) as stats_date FROM ( select object_id, stats_date(object_id, stats_id) as stats_date from sys.stats) as d GROUP BY object_id ) as d ON d.object_id = t.object_id where ps.row_count > 0 group by s.[name], t.[name], t.object_id, COALESCE(d.stats_date, ''1900-01-01'') ' SET ANSI_WARNINGS OFF; Insert #status EXEC ( @SQL); SET ANSI_WARNINGS ON; END FETCH NEXT FROM cDB INTO @dbNameENDCLOSE cDBDEALLOCATE cDBDECLARE cStats CURSORREAD_ONLYFOR SELECT databaseID , databaseName , objectID , schemaName , objectName , lastUpdateDate FROM #status WHERE DATEDIFF(dd, lastUpdateDate, GETDATE()) >= @minDays ORDER BY lastUpdateDate ASC, page_count desc, [objectName] ASC OPEN cStatsFETCH NEXT FROM cStats INTO @databaseID, @dbName, @objectID, @schemaName, @objectName, @lastUpdateDateWHILE (@@fetch_status <> -1)BEGIN IF (@@fetch_status <> -2) BEGIN IF DATEDIFF(mi, @startTime, GETDATE()) > @timeLimit BEGIN PRINT '[ ' + CAST(GETDATE() AS VARCHAR(100)) + ' ] ' + '*** Time Limit Reached ***'; GOTO __DONE; END SELECT @SQL = 'UPDATE STATISTICS ' + QUOTENAME(@dBName) + '.' + QUOTENAME(@schemaName) + '.' + QUOTENAME(@ObjectName) + ' WITH SAMPLE ' + CAST(@samplePercent AS NVARCHAR(100)) + ' PERCENT;'; IF @printSQL = 1 PRINT '[ ' + CAST(GETDATE() AS VARCHAR(100)) + ' ] ' + @SQL + ' (Last Updated: ' + CAST(@lastUpdateDate AS VARCHAR(100)) + ')' IF @executeSQL = 1 BEGIN EXEC (@SQL); END END FETCH NEXT FROM cStats INTO @databaseID, @dbName, @objectID, @schemaName, @objectName, @lastUpdateDateEND__DONE:CLOSE cStatsDEALLOCATE cStatsPRINT '[ ' + CAST(GETDATE() AS VARCHAR(100)) + ' ] ' + 'Completed.'GO

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