Fragmented SQL indexes can cause of number of issues in a GlobalSearch database, including:
- Searching index values is slow or unresponsive.
- Inability to Add/Edit Fields.
- Opening a document is slow.
- Results not displaying in GlobalSearch.
The following scripts can be used to identify and defragment any SQL indexes that might be causing database slowdown. This script can be put into a batch file and run as a scheduled task, run manually or as a stored procedure.
It is highly recommended to take backups before performing any SQL operations. Failure to perform proper backups may result in permanent data loss.
Identifying Fragmented Index Script
Locate Fragmented Indexes
SELECT B.name AS TableName , C.name AS IndexName , C.fill_factor AS IndexFillFactor , D.ROWS AS RowsCount , A.avg_fragmentation_in_percent , A.page_count FROM sys.dm_db_index_physical_stats(DB_ID(),NULL,NULL,NULL,NULL) A INNER JOIN sys.objects B ON A.OBJECT_ID = B.OBJECT_ID INNER JOIN sys.indexes C ON B.OBJECT_ID = C.OBJECT_ID AND A.index_id = C.index_id INNER JOIN sys.partitions D ON B.OBJECT_ID = D.OBJECT_ID AND A.index_id = D.index_id WHERE C.index_id > 0 and A.avg_fragmentation_in_percent >15 ORDER BY TABLENAME
The above script will return a table-set of indexes and list their row count and average fragmentation. Any fragmented indexes with over 15% fragmentation will appear here. If no results are returned it may be because you are running the script against the wrong SQL database or that there are no indexes with fragmentation above 15%. To test this you can comment out (or remove completely) the line second from the bottom with two minus signs (--). This line is the filter to show only those indexes with fragmentation above 15%, removing it will show all of the results. To change the database that you are running the script against (in SSMS) use the dropdown in the tool bar to select the correct SQL database.
Don’t be scared if you see some high numbers – sometimes tables with only a couple hundred rows can return high fragmentation. This shouldn’t be considered too problematic. If however, you see indexes with thousands of rows coming back as highly fragmented (50% or higher) it may be worth running a defragmentation. To do that, you can run the script below:
The following script loops through the tables using a SQL cursor to rebuild the indexes, reducing the fragmentation on affected tables.
The following script may cause SQL performance degradation. Consider running when the server is not in use.
Fix Fragmented Indexes
DECLARE @TableName VARCHAR(255) DECLARE @SQL NVARCHAR(500) DECLARE @FILLFACTOR INT SET @FILLFACTOR = 80 DECLARE TableCursor CURSOR FOR SELECT OBJECT_SCHEMA_NAME([OBJECT_ID])+'.'+name AS TableName FROM sys.tables OPEN TableCursor FETCH NEXT FROM TableCursor INTO @TableName WHILE @@FETCH_STATUS = 0 BEGIN SET @SQL = 'ALTER INDEX ALL ON ' + @TableName + ' REBUILD WITH (FILLFACTOR = ' + CONVERT(VARCHAR(3),@FILLFACTOR) + ')' EXEC (@SQL) FETCH NEXT FROM TableCursor INTO @TableName END CLOSE TableCursor DEALLOCATE TableCursor GO
After running this script, it is recommended you run the "Identifying Fragmented Index Script" once again to see if you’ve lessened the fragmentation. Continue to do this until you see fragmentation go away entirely or until larger indexes are showing minimal fragmentation. It may never completely go away, but lessening index fragmentation can definitely help speed up a database and make things run a little smoother.