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--- sql:reidexsusdb [12.08.2021 12:23] – Ladislav Vojtíšek
+++ sql:reidexsusdb [12.08.2021 13:00] (aktuální) – Ladislav Vojtíšek
@@ Řádek 2: / Řádek 2: @@
 Spuštěním tohoto skriptu provedete základní úlohy údržby na databázi SUSDB:
-* Identifikace fragmentovaných indexů a jejich defragmentace.
+* Identifikace fragmentovaných indexů a jejich defragmentace.\\
-* Aktualizace potenciálně zastaralých statistik tabulek.
+* Aktualizace potenciálně zastaralých statistik tabulek.\\
+  USE SUSDB;
+  GO
+  SET NOCOUNT ON;
+  -- Rebuild or reorganize indexes based on their fragmentation levels
+  DECLARE @work_to_do TABLE (
+      objectid int
+      , indexid int
+      , pagedensity float
+      , fragmentation float
+      , numrows int
+  )
+  DECLARE @objectid int;
+  DECLARE @indexid int;
+  DECLARE @schemaname nvarchar(130);
+  DECLARE @objectname nvarchar(130);
+  DECLARE @indexname nvarchar(130);
+  DECLARE @numrows int
+  DECLARE @density float;
+  DECLARE @fragmentation float;
+  DECLARE @command nvarchar(4000);
+  DECLARE @fillfactorset bit
+  DECLARE @numpages int
+  -- Select indexes that need to be defragmented based on the following
+  -- * Page density is low
+  -- * External fragmentation is high in relation to index size
+  PRINT 'Estimating fragmentation: Begin. ' + convert(nvarchar, getdate(), 121)
+  INSERT @work_to_do
+  SELECT
+      f.object_id
+      , index_id
+      , avg_page_space_used_in_percent
+      , avg_fragmentation_in_percent
+      , record_count
+  FROM
+      sys.dm_db_index_physical_stats (DB_ID(), NULL, NULL , NULL, 'SAMPLED') AS f
+  WHERE
+      (f.avg_page_space_used_in_percent < 85.0 and f.avg_page_space_used_in_percent/100.0 * page_count < page_count - 1)
+      or (f.page_count > 50 and f.avg_fragmentation_in_percent > 15.0)
+      or (f.page_count > 10 and f.avg_fragmentation_in_percent > 80.0)
+  PRINT 'Number of indexes to rebuild: ' + cast(@@ROWCOUNT as nvarchar(20))
+  PRINT 'Estimating fragmentation: End. ' + convert(nvarchar, getdate(), 121)
+  SELECT @numpages = sum(ps.used_page_count)
+  FROM
+      @work_to_do AS fi
+      INNER JOIN sys.indexes AS i ON fi.objectid = i.object_id and fi.indexid = i.index_id
+      INNER JOIN sys.dm_db_partition_stats AS ps on i.object_id = ps.object_id and i.index_id = ps.index_id
+  -- Declare the cursor for the list of indexes to be processed.
+  DECLARE curIndexes CURSOR FOR SELECT * FROM @work_to_do
+  -- Open the cursor.
+  OPEN curIndexes
+  -- Loop through the indexes
+  WHILE (1=1)
+  BEGIN
+      FETCH NEXT FROM curIndexes
+      INTO @objectid, @indexid, @density, @fragmentation, @numrows;
+      IF @@FETCH_STATUS < 0 BREAK;
+      SELECT
+          @objectname = QUOTENAME(o.name)
+          , @schemaname = QUOTENAME(s.name)
+      FROM
+          sys.objects AS o
+          INNER JOIN sys.schemas as s ON s.schema_id = o.schema_id
+      WHERE
+          o.object_id = @objectid;
+      SELECT
+          @indexname = QUOTENAME(name)
+          , @fillfactorset = CASE fill_factor WHEN 0 THEN 0 ELSE 1 END
+      FROM
+          sys.indexes
+      WHERE
+          object_id = @objectid AND index_id = @indexid;
+      IF ((@density BETWEEN 75.0 AND 85.0) AND @fillfactorset = 1) OR (@fragmentation < 30.0)
+          SET @command = N'ALTER INDEX ' + @indexname + N' ON ' + @schemaname + N'.' + @objectname + N' REORGANIZE';
+      ELSE IF @numrows >= 5000 AND @fillfactorset = 0
+          SET @command = N'ALTER INDEX ' + @indexname + N' ON ' + @schemaname + N'.' + @objectname + N' REBUILD WITH (FILLFACTOR = 90)';
+      ELSE
+          SET @command = N'ALTER INDEX ' + @indexname + N' ON ' + @schemaname + N'.' + @objectname + N' REBUILD';
+      PRINT convert(nvarchar, getdate(), 121) + N' Executing: ' + @command;
+      EXEC (@command);
+      PRINT convert(nvarchar, getdate(), 121) + N' Done.';
+  END
+  -- Close and deallocate the cursor.
+  CLOSE curIndexes;
+  DEALLOCATE curIndexes;
+  IF EXISTS (SELECT * FROM @work_to_do)
+  BEGIN
+      PRINT 'Estimated number of pages in fragmented indexes: ' + cast(@numpages as nvarchar(20))
+      SELECT @numpages = @numpages - sum(ps.used_page_count)
+      FROM
+          @work_to_do AS fi
+          INNER JOIN sys.indexes AS i ON fi.objectid = i.object_id and fi.indexid = i.index_id
+          INNER JOIN sys.dm_db_partition_stats AS ps on i.object_id = ps.object_id and i.index_id = ps.index_id
+      PRINT 'Estimated number of pages freed: ' + cast(@numpages as nvarchar(20))
+  END
+  GO
+  --Update all statistics
+  PRINT 'Updating all statistics.' + convert(nvarchar, getdate(), 121)
+  EXEC sp_updatestats
+  PRINT 'Done updating statistics.' + convert(nvarchar, getdate(), 121)
+  GO