24/10/2013

Defrag SharePoint DB Indexes

Been doing some research into the defrag rates of SharePoint content DB's in order to maximise performance

I ran some sime commands to find out the level of defragmentation....

DBCC SHOWCONTIG - this will show you the level of defragmentation in your DB's



DBCC SHOWCONTIG scanning 'WorkflowAssociation' table...
Table: 'WorkflowAssociation' (1490104349); index ID: 1, database ID: 7
TABLE level scan performed.
- Pages Scanned................................: 5
- Extents Scanned..............................: 5
- Extent Switches..............................: 4
- Avg. Pages per Extent........................: 1.0
- Scan Density [Best Count:Actual Count].......: 20.00% [1:5]
- Logical Scan Fragmentation ..................: 80.00%
- Extent Scan Fragmentation ...................: 80.00%
- Avg. Bytes Free per Page.....................: 2001.2
- Avg. Page Density (full).....................: 75.28%


The following SQL will allow you to set the defrag limit and defrag all your tables.

*Perform a 'USE ' to select the database in which to run the script.*/
-- Declare variables
SET NOCOUNT ON;
DECLARE @tablename varchar(255);
DECLARE @execstr varchar(400);
DECLARE @objectid int;
DECLARE @indexid int;
DECLARE @frag decimal;
DECLARE @maxfrag decimal;

-- Decide on the maximum fragmentation to allow for.
SELECT @maxfrag = 30.0;

-- Declare a cursor.
DECLARE tables CURSOR FOR
SELECT TABLE_SCHEMA + '.' + TABLE_NAME
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_TYPE = 'BASE TABLE';

-- Create the table.
CREATE TABLE #fraglist (
ObjectName char(255),
ObjectId int,
IndexName char(255),
IndexId int,
Lvl int,
CountPages int,
CountRows int,
MinRecSize int,
MaxRecSize int,
AvgRecSize int,
ForRecCount int,
Extents int,
ExtentSwitches int,
AvgFreeBytes int,
AvgPageDensity int,
ScanDensity decimal,
BestCount int,
ActualCount int,
LogicalFrag decimal,
ExtentFrag decimal);

-- Open the cursor.
OPEN tables;

-- Loop through all the tables in the database.
FETCH NEXT
FROM tables
INTO @tablename;

WHILE @@FETCH_STATUS = 0
BEGIN
-- Do the showcontig of all indexes of the table
INSERT INTO #fraglist
EXEC ('DBCC SHOWCONTIG (''' + @tablename + ''')
WITH FAST, TABLERESULTS, ALL_INDEXES, NO_INFOMSGS');
FETCH NEXT
FROM tables
INTO @tablename;
END;

-- Close and deallocate the cursor.
CLOSE tables;
DEALLOCATE tables;

-- Declare the cursor for the list of indexes to be defragged.
DECLARE indexes CURSOR FOR
SELECT ObjectName, ObjectId, IndexId, LogicalFrag
FROM #fraglist
WHERE LogicalFrag >= @maxfrag
AND INDEXPROPERTY (ObjectId, IndexName, 'IndexDepth') > 0;

-- Open the cursor.
OPEN indexes;

-- Loop through the indexes.
FETCH NEXT
FROM indexes
INTO @tablename, @objectid, @indexid, @frag;

WHILE @@FETCH_STATUS = 0
BEGIN
PRINT 'Executing DBCC INDEXDEFRAG (0, ' + RTRIM(@tablename) + ',
' + RTRIM(@indexid) + ') - fragmentation currently '
+ RTRIM(CONVERT(varchar(15),@frag)) + '%';
SELECT @execstr = 'DBCC INDEXDEFRAG (0, ' + RTRIM(@objectid) + ',
' + RTRIM(@indexid) + ')';
EXEC (@execstr);

FETCH NEXT
FROM indexes
INTO @tablename, @objectid, @indexid, @frag;
END;

-- Close and deallocate the cursor.
CLOSE indexes;
DEALLOCATE indexes;

-- Delete the temporary table.
DROP TABLE #fraglist;
GO

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