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/****************************************************************************** |
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This sample T-SQL script performs basic maintenance tasks on SUSDB |
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1. Identifies indexes that are fragmented and defragments them. For certain |
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tables, a fill-factor is set in order to improve insert performance. |
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Based on MSDN sample at http://msdn2.microsoft.com/en-us/library/ms188917.aspx |
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and tailored for SUSDB requirements |
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2. Updates potentially out-of-date table statistics. |
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******************************************************************************/ |
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USE SUSDB; |
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GO |
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SET NOCOUNT ON; |
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-- Rebuild or reorganize indexes based on their fragmentation levels |
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DECLARE @work_to_do TABLE ( |
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objectid int |
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, indexid int |
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, pagedensity float |
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, fragmentation float |
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, numrows int |
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) |
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DECLARE @objectid int; |
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DECLARE @indexid int; |
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DECLARE @schemaname nvarchar(130); |
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DECLARE @objectname nvarchar(130); |
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DECLARE @indexname nvarchar(130); |
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DECLARE @numrows int |
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DECLARE @density float; |
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DECLARE @fragmentation float; |
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DECLARE @command nvarchar(4000); |
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DECLARE @fillfactorset bit |
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DECLARE @numpages int |
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-- Select indexes that need to be defragmented based on the following |
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-- * Page density is low |
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-- * External fragmentation is high in relation to index size |
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PRINT 'Estimating fragmentation: Begin. ' + convert(nvarchar, getdate(), 121) |
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INSERT @work_to_do |
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SELECT |
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f.object_id |
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, index_id |
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, avg_page_space_used_in_percent |
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, avg_fragmentation_in_percent |
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, record_count |
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FROM |
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sys.dm_db_index_physical_stats (DB_ID(), NULL, NULL , NULL, 'SAMPLED') AS f |
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WHERE |
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(f.avg_page_space_used_in_percent < 85.0 and f.avg_page_space_used_in_percent/100.0 * page_count < page_count - 1) |
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or (f.page_count > 50 and f.avg_fragmentation_in_percent > 15.0) |
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or (f.page_count > 10 and f.avg_fragmentation_in_percent > 80.0) |
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PRINT 'Number of indexes to rebuild: ' + cast(@@ROWCOUNT as nvarchar(20)) |
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PRINT 'Estimating fragmentation: End. ' + convert(nvarchar, getdate(), 121) |
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SELECT @numpages = sum(ps.used_page_count) |
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FROM |
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@work_to_do AS fi |
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INNER JOIN sys.indexes AS i ON fi.objectid = i.object_id and fi.indexid = i.index_id |
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INNER JOIN sys.dm_db_partition_stats AS ps on i.object_id = ps.object_id and i.index_id = ps.index_id |
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-- Declare the cursor for the list of indexes to be processed. |
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DECLARE curIndexes CURSOR FOR SELECT * FROM @work_to_do |
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-- Open the cursor. |
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OPEN curIndexes |
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-- Loop through the indexes |
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WHILE (1=1) |
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BEGIN |
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FETCH NEXT FROM curIndexes |
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INTO @objectid, @indexid, @density, @fragmentation, @numrows; |
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IF @@FETCH_STATUS < 0 BREAK; |
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SELECT |
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@objectname = QUOTENAME(o.name) |
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, @schemaname = QUOTENAME(s.name) |
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FROM |
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sys.objects AS o |
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INNER JOIN sys.schemas as s ON s.schema_id = o.schema_id |
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WHERE |
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o.object_id = @objectid; |
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SELECT |
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@indexname = QUOTENAME(name) |
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, @fillfactorset = CASE fill_factor WHEN 0 THEN 0 ELSE 1 END |
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FROM |
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sys.indexes |
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WHERE |
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object_id = @objectid AND index_id = @indexid; |
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IF ((@density BETWEEN 75.0 AND 85.0) AND @fillfactorset = 1) OR (@fragmentation < 30.0) |
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SET @command = N'ALTER INDEX ' + @indexname + N' ON ' + @schemaname + N'.' + @objectname + N' REORGANIZE'; |
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ELSE IF @numrows >= 5000 AND @fillfactorset = 0 |
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SET @command = N'ALTER INDEX ' + @indexname + N' ON ' + @schemaname + N'.' + @objectname + N' REBUILD WITH (FILLFACTOR = 90)'; |
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ELSE |
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SET @command = N'ALTER INDEX ' + @indexname + N' ON ' + @schemaname + N'.' + @objectname + N' REBUILD'; |
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PRINT convert(nvarchar, getdate(), 121) + N' Executing: ' + @command; |
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EXEC (@command); |
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PRINT convert(nvarchar, getdate(), 121) + N' Done.'; |
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END |
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-- Close and deallocate the cursor. |
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CLOSE curIndexes; |
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DEALLOCATE curIndexes; |
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IF EXISTS (SELECT * FROM @work_to_do) |
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BEGIN |
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PRINT 'Estimated number of pages in fragmented indexes: ' + cast(@numpages as nvarchar(20)) |
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SELECT @numpages = @numpages - sum(ps.used_page_count) |
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FROM |
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@work_to_do AS fi |
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INNER JOIN sys.indexes AS i ON fi.objectid = i.object_id and fi.indexid = i.index_id |
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INNER JOIN sys.dm_db_partition_stats AS ps on i.object_id = ps.object_id and i.index_id = ps.index_id |
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PRINT 'Estimated number of pages freed: ' + cast(@numpages as nvarchar(20)) |
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END |
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GO |
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--Update all statistics |
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PRINT 'Updating all statistics.' + convert(nvarchar, getdate(), 121) |
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EXEC sp_updatestats |
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PRINT 'Done updating statistics.' + convert(nvarchar, getdate(), 121) |
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GO |
Thanks!