Index Defrag Script, v3.0
June 23, 2009 by Michelle Ufford · 89 Comments
Filed under: Performance & Tuning, SQL 2008, Syndication, T-SQL Scripts
Filed under: Performance & Tuning, SQL 2008, Syndication, T-SQL Scripts
I’ve just completed the latest version of my index defrag script! Here’s a brief list of the updates:
- Fixed a bug with the LOB logic. In the previous version, after a LOB was encountered, all subsequent indexes would be reorganized.
- Added support for stat rebuilds after the index defrag is complete (@rebuildStats)
- Added an exclusion list table (dba_indexDefragExclusion) to support index scheduling
- Modified logging to show which defrags are “in progress”; added columns to dba_indexDefragLog
- Added support for the defrag of the model and msdb databases
- Added @scanMode as a configurable parameter
So what can this index defrag script do? Well, for starters, you can:
- Schedule it to run with the default settings; it works “right out of the box” with no additional configuration necessary
- Run this one script from a centralized database for all databases on a server
- Run this script for a specific database or table
- Configure custom threshold limits and the point at which a rebuild should be performed (instead of a reorganize)
- Defrag individual partitions
- Log its actions and the duration of the defrag
- Run in “commands only” mode (@executeSQL = 0, @printCommands = 1)
- Customize performance parameters such as @maxDopRestriction and @defragDelay to minimize impact on the server
- Schedule specific indexes to only be defragged on weekends, or every other day
To use this last option, you need to add a record to the dba_indexDefragExclusion table. I think all of the columns are pretty self-explanatory except the [exclusionMask] column. The way this works is each day of the week is assigned a value:
1=Sunday, 2=Monday, 4=Tuesday, 8=Wednesday, 16=Thursday, 32=Friday, 64=Saturday
Take a SUM of the values for the days that you want excluded. So if you want an index to only be defragged on weekends, you would add up Monday through Friday (2+4+8+16+32) and use a value of 62 for the exclusionMask column. For a little more information on how this works, check out my blog post on Bitwise Operations.
Please note: if you don’t insert any records into the dba_indexDefragExclusion table, by default all indexes will be defragged every run-time if they exceed the specified thresholds. This is normal behavior and may be perfectly fine in your environment. However, if the dba_indexDefragExclusion table does not exist, the script will fail.
I try to document each parameter within the code, so check the comments section in the script for a full list of parameters and what they do.
Special thanks to everyone who helped beta test this script! 
Without further ado, the script:
/* Drop Table Scripts: Drop Table dbo.dba_indexDefragLog; Drop Table dbo.dba_indexDefragExclusion; */ IF Not Exists(SELECT [OBJECT_ID] FROM sys.tables WHERE [name] In (N'dba_indexDefragLog', 'dba_indexDefragExclusion')) BEGIN CREATE TABLE dbo.dba_indexDefragLog ( indexDefrag_id INT IDENTITY(1,1) Not Null , databaseID INT Not Null , databaseName NVARCHAR(128) Not Null , objectID INT Not Null , objectName NVARCHAR(128) Not Null , indexID INT Not Null , indexName NVARCHAR(128) Not Null , partitionNumber SMALLINT Not Null , fragmentation FLOAT Not Null , page_count INT Not Null , dateTimeStart DATETIME Not Null , dateTimeEnd DATETIME Null , durationSeconds INT Null CONSTRAINT PK_indexDefragLog PRIMARY KEY CLUSTERED (indexDefrag_id) ); PRINT 'dba_indexDefragLog Table Created'; CREATE TABLE dbo.dba_indexDefragExclusion ( databaseID INT Not Null , databaseName NVARCHAR(128) Not Null , objectID INT Not Null , objectName NVARCHAR(128) Not Null , indexID INT Not Null , indexName NVARCHAR(128) Not Null , exclusionMask INT Not Null /* 1=Sunday, 2=Monday, 4=Tuesday, 8=Wednesday, 16=Thursday, 32=Friday, 64=Saturday */ CONSTRAINT PK_indexDefragExclusion PRIMARY KEY CLUSTERED (databaseID, objectID, indexID) ); PRINT 'dba_indexDefragExclusion Table Created'; END ELSE RAISERROR('One or more tables already exist. Please drop or rename before proceeding.', 16, 0); IF OBJECTPROPERTY(OBJECT_ID('dbo.dba_indexDefrag_sp'), N'IsProcedure') = 1 BEGIN DROP PROCEDURE dbo.dba_indexDefrag_sp; PRINT 'Procedure dba_indexDefrag_sp dropped'; END; Go CREATE PROCEDURE dbo.dba_indexDefrag_sp /* Declare Parameters */ @minFragmentation FLOAT = 5.0 /* in percent, will not defrag if fragmentation less than specified */ , @rebuildThreshold FLOAT = 30.0 /* in percent, greater than @rebuildThreshold will result in rebuild instead of reorg */ , @executeSQL BIT = 1 /* 1 = execute; 0 = print command only */ , @DATABASE VARCHAR(128) = Null /* Option to specify a database name; null will return all */ , @tableName VARCHAR(4000) = Null -- databaseName.schema.tableName /* Option to specify a table name; null will return all */ , @scanMode VARCHAR(10) = N'LIMITED' /* Options are LIMITED, SAMPLED, and DETAILED */ , @onlineRebuild BIT = 1 /* 1 = online rebuild; 0 = offline rebuild; only in Enterprise */ , @maxDopRestriction TINYINT = Null /* Option to restrict the number of processors for the operation; only in Enterprise */ , @printCommands BIT = 0 /* 1 = print commands; 0 = do not print commands */ , @printFragmentation BIT = 0 /* 1 = print fragmentation prior to defrag; 0 = do not print */ , @defragDelay CHAR(8) = '00:00:05' /* time to wait between defrag commands */ , @debugMode BIT = 0 /* display some useful comments to help determine if/where issues occur */ , @rebuildStats BIT = 1 /* option to rebuild stats after completed index defrags */ AS /********************************************************************************* Name: dba_indexDefrag_sp Author: Michelle Ufford, http://sqlfool.com Purpose: Defrags all indexes for the current database Notes: CAUTION: TRANSACTION LOG SIZE SHOULD BE MONITORED CLOSELY WHEN DEFRAGMENTING. @minFragmentation defaulted to 10%, will not defrag if fragmentation is less than that @rebuildThreshold defaulted to 30% as recommended by Microsoft in BOL; greater than 30% will result in rebuild instead @executeSQL 1 = execute the SQL generated by this proc; 0 = print command only @database Optional, specify specific database name to defrag; If not specified, all non-system databases will be defragged. @tableName Specify if you only want to defrag indexes for a specific table, format = databaseName.schema.tableName; if not specified, all tables will be defragged. @scanMode Specifies which scan mode to use to determine fragmentation levels. Options are: LIMITED - scans the parent level; quickest mode, recommended for most cases. SAMPLED - samples 1% of all data pages; if less than 10k pages, performs a DETAILED scan. DETAILED - scans all data pages. Use great care with this mode, as it can cause performance issues. @onlineRebuild 1 = online rebuild; 0 = offline rebuild @maxDopRestriction Option to specify a processor limit for index rebuilds @printCommands 1 = print commands to screen; 0 = do not print commands @printFragmentation 1 = print fragmentation to screen; 0 = do not print fragmentation @defragDelay Time to wait between defrag commands; gives the server a little time to catch up @debugMode 1 = display debug comments; helps with troubleshooting 0 = do not display debug comments @rebuildStats Affects only statistics that need to be rebuilt 1 = rebuild stats 0 = do not rebuild stats Called by: SQL Agent Job or DBA Date Initials Version Description ---------------------------------------------------------------------------- 2007-12-18 MFU 1.0 Initial Release 2008-10-17 MFU 1.1 Added @defragDelay, CIX_temp_indexDefragList 2008-11-17 MFU 1.2 Added page_count to log table , added @printFragmentation option 2009-03-17 MFU 2.0 Provided support for centralized execution , consolidated Enterprise & Standard versions , added @debugMode, @maxDopRestriction , modified LOB and partition logic 2009-06-18 MFU 3.0 Fixed bug in LOB logic, added @scanMode option , added support for stat rebuilds (@rebuildStats) , support model and msdb defrag , added columns to the dba_indexDefragLog table , modified logging to show "in progress" defrags , added defrag exclusion list (scheduling) ********************************************************************************* Exec dbo.dba_indexDefrag_sp @executeSQL = 0 , @printCommands = 1 , @debugMode = 1 , @printFragmentation = 1; *********************************************************************************/ SET NOCOUNT ON; SET XACT_Abort ON; SET Ansi_Padding ON; SET Ansi_Warnings ON; SET ArithAbort ON; SET Concat_Null_Yields_Null ON; SET Numeric_RoundAbort OFF; SET Quoted_Identifier ON; BEGIN IF @debugMode = 1 RAISERROR('Undusting the cogs and starting up...', 0, 42) WITH NoWait; /* Declare our variables */ DECLARE @objectID INT , @databaseID INT , @databaseName NVARCHAR(128) , @indexID INT , @partitionCount BIGINT , @schemaName NVARCHAR(128) , @objectName NVARCHAR(128) , @indexName NVARCHAR(128) , @partitionNumber SMALLINT , @fragmentation FLOAT , @pageCount INT , @sqlCommand NVARCHAR(4000) , @rebuildCommand NVARCHAR(200) , @dateTimeStart DATETIME , @dateTimeEnd DATETIME , @containsLOB BIT , @editionCheck BIT , @debugMessage VARCHAR(128) , @updateSQL NVARCHAR(4000) , @partitionSQL NVARCHAR(4000) , @partitionSQL_Param NVARCHAR(1000) , @LOB_SQL NVARCHAR(4000) , @LOB_SQL_Param NVARCHAR(1000) , @rebuildStatsID INT , @rebuildStatsSQL NVARCHAR(1000) , @indexDefrag_id INT; /* Create our temporary tables */ CREATE TABLE #indexDefragList ( databaseID INT , databaseName NVARCHAR(128) , objectID INT , indexID INT , partitionNumber SMALLINT , fragmentation FLOAT , page_count INT , defragStatus BIT , schemaName NVARCHAR(128) Null , objectName NVARCHAR(128) Null , indexName NVARCHAR(128) Null ); CREATE TABLE #databaseList ( databaseID INT , databaseName VARCHAR(128) , scanStatus BIT , statsStatus BIT ); CREATE TABLE #processor ( [INDEX] INT , Name VARCHAR(128) , Internal_Value INT , Character_Value INT ); IF @debugMode = 1 RAISERROR('Beginning validation...', 0, 42) WITH NoWait; /* Just a little validation... */ IF @minFragmentation Not Between 0.00 And 100.0 SET @minFragmentation = 10.0; IF @rebuildThreshold Not Between 0.00 And 100.0 SET @rebuildThreshold = 30.0; IF @defragDelay Not Like '00:[0-5][0-9]:[0-5][0-9]' SET @defragDelay = '00:00:05'; IF @scanMode Not In ('LIMITED', 'SAMPLED', 'DETAILED') SET @scanMode = 'LIMITED'; /* Make sure we're not exceeding the number of processors we have available */ INSERT INTO #processor EXECUTE XP_MSVER 'ProcessorCount'; IF @maxDopRestriction IS Not Null And @maxDopRestriction > (SELECT Internal_Value FROM #processor) SELECT @maxDopRestriction = Internal_Value FROM #processor; /* Check our server version; 1804890536 = Enterprise, 610778273 = Enterprise Evaluation, -2117995310 = Developer */ IF (SELECT SERVERPROPERTY('EditionID')) In (1804890536, 610778273, -2117995310) SET @editionCheck = 1 -- supports online rebuilds ELSE SET @editionCheck = 0; -- does not support online rebuilds IF @debugMode = 1 RAISERROR('Grabbing a list of our databases...', 0, 42) WITH NoWait; /* Retrieve the list of databases to investigate */ INSERT INTO #databaseList SELECT database_id , name , 0 -- not scanned yet for fragmentation , 0 -- statistics not yet updated FROM sys.databases WHERE name = IsNull(@DATABASE, name) And [name] Not In ('master', 'tempdb')-- exclude system databases And [STATE] = 0; -- state must be ONLINE IF @debugMode = 1 RAISERROR('Looping through our list of databases and checking for fragmentation...', 0, 42) WITH NoWait; /* Loop through our list of databases */ WHILE (SELECT COUNT(*) FROM #databaseList WHERE scanStatus = 0) > 0 BEGIN SELECT TOP 1 @databaseID = databaseID FROM #databaseList WHERE scanStatus = 0; SELECT @debugMessage = ' working on ' + DB_NAME(@databaseID) + '...'; IF @debugMode = 1 RAISERROR(@debugMessage, 0, 42) WITH NoWait; /* Determine which indexes to defrag using our user-defined parameters */ INSERT INTO #indexDefragList SELECT database_id AS databaseID , QUOTENAME(DB_NAME(database_id)) AS 'databaseName' , [OBJECT_ID] AS objectID , index_id AS indexID , partition_number AS partitionNumber , avg_fragmentation_in_percent AS fragmentation , page_count , 0 AS 'defragStatus' /* 0 = unprocessed, 1 = processed */ , Null AS 'schemaName' , Null AS 'objectName' , Null AS 'indexName' FROM sys.dm_db_index_physical_stats (@databaseID, OBJECT_ID(@tableName), Null , Null, @scanMode) WHERE avg_fragmentation_in_percent >= @minFragmentation And index_id > 0 -- ignore heaps And page_count > 8 -- ignore objects with less than 1 extent And index_level = 0 -- leaf-level nodes only, supports @scanMode OPTION (MaxDop 2); /* Keep track of which databases have already been scanned */ UPDATE #databaseList SET scanStatus = 1 WHERE databaseID = @databaseID; END CREATE CLUSTERED INDEX CIX_temp_indexDefragList ON #indexDefragList(databaseID, objectID, indexID, partitionNumber); /* Delete any indexes from our to-do that are also in our exclusion list for today */ DELETE idl FROM #indexDefragList AS idl Join dbo.dba_indexDefragExclusion AS ide ON idl.databaseID = ide.databaseID And idl.objectID = ide.objectID And idl.indexID = ide.indexID WHERE exclusionMask & POWER(2, DATEPART(weekday, GETDATE())-1) > 0; SELECT @debugMessage = 'Looping through our list... there''s ' + CAST(COUNT(*) AS VARCHAR(10)) + ' indexes to defrag!' FROM #indexDefragList; IF @debugMode = 1 RAISERROR(@debugMessage, 0, 42) WITH NoWait; /* Begin our loop for defragging */ WHILE (SELECT COUNT(*) FROM #indexDefragList WHERE defragStatus = 0) > 0 BEGIN IF @debugMode = 1 RAISERROR(' Picking an index to beat into shape...', 0, 42) WITH NoWait; /* Grab the most fragmented index first to defrag */ SELECT TOP 1 @objectID = objectID , @indexID = indexID , @databaseID = databaseID , @databaseName = databaseName , @fragmentation = fragmentation , @partitionNumber = partitionNumber , @pageCount = page_count FROM #indexDefragList WHERE defragStatus = 0 ORDER BY fragmentation DESC; IF @debugMode = 1 RAISERROR(' Looking up the specifics for our index...', 0, 42) WITH NoWait; /* Look up index information */ SELECT @updateSQL = N'Update idl Set schemaName = QuoteName(s.name) , objectName = QuoteName(o.name) , indexName = QuoteName(i.name) From #indexDefragList As idl Inner Join ' + @databaseName + '.sys.objects As o On idl.objectID = o.object_id Inner Join ' + @databaseName + '.sys.indexes As i On o.object_id = i.object_id Inner Join ' + @databaseName + '.sys.schemas As s On o.schema_id = s.schema_id Where o.object_id = ' + CAST(@objectID AS VARCHAR(10)) + ' And i.index_id = ' + CAST(@indexID AS VARCHAR(10)) + ' And i.type > 0 And idl.databaseID = ' + CAST(@databaseID AS VARCHAR(10)); EXECUTE SP_EXECUTESQL @updateSQL; /* Grab our object names */ SELECT @objectName = objectName , @schemaName = schemaName , @indexName = indexName FROM #indexDefragList WHERE objectID = @objectID And indexID = @indexID And databaseID = @databaseID; IF @debugMode = 1 RAISERROR(' Grabbing the partition count...', 0, 42) WITH NoWait; /* Determine if the index is partitioned */ SELECT @partitionSQL = 'Select @partitionCount_OUT = Count(*) From ' + @databaseName + '.sys.partitions Where object_id = ' + CAST(@objectID AS VARCHAR(10)) + ' And index_id = ' + CAST(@indexID AS VARCHAR(10)) + ';' , @partitionSQL_Param = '@partitionCount_OUT int OutPut'; EXECUTE SP_EXECUTESQL @partitionSQL, @partitionSQL_Param, @partitionCount_OUT = @partitionCount OUTPUT; IF @debugMode = 1 RAISERROR(' Seeing if there''s any LOBs to be handled...', 0, 42) WITH NoWait; /* Determine if the table contains LOBs */ SELECT @LOB_SQL = ' Select @containsLOB_OUT = Count(*) From ' + @databaseName + '.sys.columns With (NoLock) Where [object_id] = ' + CAST(@objectID AS VARCHAR(10)) + ' And (system_type_id In (34, 35, 99) Or max_length = -1);' /* system_type_id --> 34 = image, 35 = text, 99 = ntext max_length = -1 --> varbinary(max), varchar(max), nvarchar(max), xml */ , @LOB_SQL_Param = '@containsLOB_OUT int OutPut'; EXECUTE SP_EXECUTESQL @LOB_SQL, @LOB_SQL_Param, @containsLOB_OUT = @containsLOB OUTPUT; IF @debugMode = 1 RAISERROR(' Building our SQL statements...', 0, 42) WITH NoWait; /* If there's not a lot of fragmentation, or if we have a LOB, we should reorganize */ IF @fragmentation < @rebuildThreshold Or @containsLOB >= 1 Or @partitionCount > 1 BEGIN SET @sqlCommand = N'Alter Index ' + @indexName + N' On ' + @databaseName + N'.' + @schemaName + N'.' + @objectName + N' ReOrganize'; /* If our index is partitioned, we should always reorganize */ IF @partitionCount > 1 SET @sqlCommand = @sqlCommand + N' Partition = ' + CAST(@partitionNumber AS NVARCHAR(10)); END; /* If the index is heavily fragmented and doesn't contain any partitions or LOB's, rebuild it */ IF @fragmentation >= @rebuildThreshold And IsNull(@containsLOB, 0) != 1 And @partitionCount <= 1 BEGIN /* Set online rebuild options; requires Enterprise Edition */ IF @onlineRebuild = 1 And @editionCheck = 1 SET @rebuildCommand = N' Rebuild With (Online = On'; ELSE SET @rebuildCommand = N' Rebuild With (Online = Off'; /* Set processor restriction options; requires Enterprise Edition */ IF @maxDopRestriction IS Not Null And @editionCheck = 1 SET @rebuildCommand = @rebuildCommand + N', MaxDop = ' + CAST(@maxDopRestriction AS VARCHAR(2)) + N')'; ELSE SET @rebuildCommand = @rebuildCommand + N')'; SET @sqlCommand = N'Alter Index ' + @indexName + N' On ' + @databaseName + N'.' + @schemaName + N'.' + @objectName + @rebuildCommand; END; /* Are we executing the SQL? If so, do it */ IF @executeSQL = 1 BEGIN IF @debugMode = 1 RAISERROR(' Executing SQL statements...', 0, 42) WITH NoWait; /* Grab the time for logging purposes */ SET @dateTimeStart = GETDATE(); /* Log our actions */ INSERT INTO dbo.dba_indexDefragLog ( databaseID , databaseName , objectID , objectName , indexID , indexName , partitionNumber , fragmentation , page_count , dateTimeStart ) SELECT @databaseID , @databaseName , @objectID , @objectName , @indexID , @indexName , @partitionNumber , @fragmentation , @pageCount , @dateTimeStart; SET @indexDefrag_id = SCOPE_IDENTITY(); /* Execute our defrag! */ EXECUTE SP_EXECUTESQL @sqlCommand; SET @dateTimeEnd = GETDATE(); /* Update our log with our completion time */ UPDATE dbo.dba_indexDefragLog SET dateTimeEnd = @dateTimeEnd , durationSeconds = DATEDIFF(SECOND, @dateTimeStart, @dateTimeEnd) WHERE indexDefrag_id = @indexDefrag_id; /* Just a little breather for the server */ WAITFOR Delay @defragDelay; /* Print if specified to do so */ IF @printCommands = 1 PRINT N'Executed: ' + @sqlCommand; END ELSE /* Looks like we're not executing, just printing the commands */ BEGIN IF @debugMode = 1 RAISERROR(' Printing SQL statements...', 0, 42) WITH NoWait; IF @printCommands = 1 PRINT IsNull(@sqlCommand, 'error!'); END IF @debugMode = 1 RAISERROR(' Updating our index defrag status...', 0, 42) WITH NoWait; /* Update our index defrag list so we know we've finished with that index */ UPDATE #indexDefragList SET defragStatus = 1 WHERE databaseID = @databaseID And objectID = @objectID And indexID = @indexID And partitionNumber = @partitionNumber; END /* Do we want to output our fragmentation results? */ IF @printFragmentation = 1 BEGIN IF @debugMode = 1 RAISERROR(' Displaying fragmentation results...', 0, 42) WITH NoWait; SELECT databaseID , databaseName , objectID , objectName , indexID , indexName , fragmentation , page_count FROM #indexDefragList; END; /* Do we want to rebuild stats? */ IF @rebuildStats = 1 BEGIN WHILE Exists(SELECT TOP 1 * FROM #databaseList WHERE statsStatus = 0) BEGIN /* Build our SQL statement to update stats */ SELECT TOP 1 @rebuildStatsSQL = 'Use [' + databaseName + ']; ' + 'Execute sp_updatestats;' , @rebuildStatsID = databaseID FROM #databaseList WHERE statsStatus = 0; SET @debugMessage = 'Rebuilding Statistics: ' + @rebuildStatsSQL; IF @debugMode = 1 RAISERROR(@debugMessage, 0, 42) WITH NoWait; /* Execute our stats update! */ EXECUTE SP_EXECUTESQL @rebuildStatsSQL; /* Keep track of which databases have been updated */ UPDATE #databaseList SET statsStatus = 1 WHERE databaseID = @rebuildStatsID; END; END; /* When everything is said and done, make sure to get rid of our temp table */ DROP TABLE #indexDefragList; DROP TABLE #databaseList; DROP TABLE #processor; IF @debugMode = 1 RAISERROR('DONE! Thank you for taking care of your indexes! :)', 0, 42) WITH NoWait; SET NOCOUNT OFF; RETURN 0 END Go SET Quoted_Identifier OFF SET ANSI_Nulls ON Go
A Look at Missing Indexes
April 28, 2009 by Michelle Ufford · 8 Comments
Filed under: Performance & Tuning, Syndication, T-SQL Scripts
Filed under: Performance & Tuning, Syndication, T-SQL Scripts
Tim Ford (@SQLAgentMan) recently blogged about his Top 5 SQL Server Indexing Best Practices. I thought it was a good list, and it inspired this blog post. I’ve recently been doing a little index spring cleaning, and I thought some people may be interested in the process I go through. So, here it is… a journey through madness an overview of my general missing index process.
I start with my trusty dba_missingIndexStoredProc table. If this table sounds completely foreign to you, check out my post, Find Missing Indexes In Stored Procs. Basically, I have a process that runs every night, scanning the XML of every query plan on the server to find procs that are possibly missing indexes. I then log the details for later action.
So I take a look at my table, and I find 8 stored procedures that are possibly missing indexes. Clicking on the XML link will show me the logged query plan:
Procs With Missing Indexes
Right clicking on the “Missing Index” description will give me the details of the recommended index:
Missing Index Details
Here’s an example of what SQL Server will return for you:
/* Missing Index Details from ExecutionPlan2.sqlplan The Query Processor estimates that implementing the following index could improve the query cost by 85.7327%. */ /* USE [msdb] GO CREATE NONCLUSTERED INDEX [<Name of Missing Index, sysname,>] ON [dbo].[sysjobhistory] ([job_id]) INCLUDE ([instance_id],[step_id],[sql_message_id],[sql_severity], [run_status],[run_date],[run_time],[run_duration],[operator_id_emailed], [operator_id_netsent],[operator_id_paged],[retries_attempted],[server]) GO */
I now compare the details of this proposed index to the missing index DMV suggestions, using this query:
SELECT t.name AS 'affected_table' , 'Create NonClustered Index IX_' + t.name + '_missing_' + CAST(ddmid.index_handle AS VARCHAR(10)) + ' On ' + ddmid.STATEMENT + ' (' + IsNull(ddmid.equality_columns,'') + CASE WHEN ddmid.equality_columns IS Not Null And ddmid.inequality_columns IS Not Null THEN ',' ELSE '' END + IsNull(ddmid.inequality_columns, '') + ')' + IsNull(' Include (' + ddmid.included_columns + ');', ';' ) AS sql_statement , ddmigs.user_seeks , ddmigs.user_scans , CAST((ddmigs.user_seeks + ddmigs.user_scans) * ddmigs.avg_user_impact AS INT) AS 'est_impact' , ddmigs.last_user_seek FROM sys.dm_db_missing_index_groups AS ddmig INNER JOIN sys.dm_db_missing_index_group_stats AS ddmigs ON ddmigs.group_handle = ddmig.index_group_handle INNER JOIN sys.dm_db_missing_index_details AS ddmid ON ddmig.index_handle = ddmid.index_handle INNER JOIN sys.tables AS t ON ddmid.OBJECT_ID = t.OBJECT_ID WHERE ddmid.database_id = DB_ID() --AND t.name = 'myTableName' ORDER BY CAST((ddmigs.user_seeks + ddmigs.user_scans) * ddmigs.avg_user_impact AS INT) DESC;
I usually find the data in both places, but not always. One reason why is because the missing index DMV will only store data since your last reboot. So if I’m taking a look at this DMV on Monday and I just rebooted on Sunday, I may not have enough history to give me meaningful recommendations. This is just something to be aware of.
What I’m looking for in this DMV is the number of user_seeks and the est_impact. Also, if I haven’t rebooted my server in a while, I take a look at last_user_seek so I can determine whether or not it’s still accurate.
Next, I take a look at my existing indexes using Kimberly Tripp’s sp_helpindex2 system stored proc. I use her proc instead of sp_helpindex because I need to see included columns.
If you’re wondering why I’m looking at existing indexes, the reason is because I’m looking for indexes that can be modified slightly to accommodate my missing index needs. By “modified slightly,” I mean that I’d only want to make a change to an existing index if it did not drastically change the size or composition of an index, i.e. adding one or two narrow columns as included columns. I do NOT mean making changes that double the size of your index; in those cases, you’d probably be better off creating a brand new index.
Looking at existing indexes is actually a pretty critical part of the puzzle. If I have a proc that only gets called a few times an hour and could benefit from a better index, I may not create that index if it means adding a wide, expensive index to a busy table. If I can make a small modification to an existing index, then there’s a greater chance I’ll make the change and cover my query.
At this point, I should have enough information to start making decisions. I was going to write out the path I normally take when making decisions, but I thought, “Hey! What a great time for a diagram.” So here you go:
Decision Path
Disclaimer: I’m *not* a Visio wizard, so if I butchered the use of certain symbols in my diagram, please let me know so I can a) fix it, and b) learn from it!
It’s hard to really put all of the decision paths into a single, small diagram like this. There’s a lot of variables that I’m not even touching here. But I think this is a fairly good “generic” representation of the path I take. When I hit an “end” process, it means I don’t create the missing index at this time. Maybe in the future, it’ll become necessary, but I prefer to err on the side of less indexes.
So there you have it, a brief look at my missing index process. Hopefully someone finds it helpful.
Automated Index Defrag Script
March 25, 2009 by Michelle Ufford · 35 Comments
Filed under: Performance & Tuning, SQL 2008, SQL Tips, T-SQL Scripts
Filed under: Performance & Tuning, SQL 2008, SQL Tips, T-SQL Scripts
Note: This script has been updated. You can find the latest version here: http://sqlfool.com/2009/06/index-defrag-script-v30/
So after much delay, here’s the latest and greatest version of my index defrag script.
A summary of the changes:
- Added support for centralized execution. Option to defrag indexes for a single database from another database, or for all non-system databases.
- Consolidated Enterprise and Standard versions of the script with new @editionCheck variable.
- Added parametrization for MaxDop restrictions during rebuilds; validates that the value does not exceed the actual number of processors on the server.
- Changed minimum fragmentation default value from 10 to 5 to match BOL recommendations.
- Limited defrags to objects with more than 8 pages.
- Added a debug option to give a little more insight into what’s happening and to assist with troubleshooting.
- Updated logic for handling partitions and LOBs.
And a couple of notes and explanations:
Don’t you know you can just pass NULL to sys.dm_db_index_physical_stats for the DatabaseID?
Yes, I realize you can do this. But I don’t want to defrag the system databases, i.e. tempdb, so I opted to handle it this way instead.
How long will this take?
It depends. I don’t necessarily recommend running it without specifying a database; at least, not unmonitored. You *can* do that, but it could take a while. For example, to run sys.dm_db_index_physical_stats for all databases and tables, totaling 2TB, took me 4.5 hours; that doesn’t even count the actual defrags.
Where should I put this?
It’s up to you. If you have a database for items like centralized maintenance or scratch tables, that may be a good place for it. If you prefer, you could also put this in each individual database and call it locally, too. I would not put this in the master or msdb databases.
This is pretty close to a complete rewrite, so please let me know if you encounter any bugs. And now… the code!
IF Not Exists(SELECT [OBJECT_ID] FROM sys.tables WHERE name = N'dba_indexDefragLog') BEGIN -- Drop Table dbo.dba_indexDefragLog CREATE TABLE dbo.dba_indexDefragLog ( indexDefrag_id INT IDENTITY(1,1) Not Null , databaseID INT Not Null , databaseName NVARCHAR(128) Not Null , objectID INT Not Null , objectName NVARCHAR(128) Not Null , indexID INT Not Null , indexName NVARCHAR(128) Not Null , partitionNumber SMALLINT Not Null , fragmentation FLOAT Not Null , page_count INT Not Null , dateTimeStart DATETIME Not Null , durationSeconds INT Not Null CONSTRAINT PK_indexDefragLog PRIMARY KEY CLUSTERED (indexDefrag_id) ) PRINT 'dba_indexDefragLog Table Created'; END IF OBJECTPROPERTY(OBJECT_ID('dbo.dba_indexDefrag_sp'), N'IsProcedure') = 1 BEGIN DROP PROCEDURE dbo.dba_indexDefrag_sp; PRINT 'Procedure dba_indexDefrag_sp dropped'; END; Go CREATE PROCEDURE dbo.dba_indexDefrag_sp /* Declare Parameters */ @minFragmentation FLOAT = 5.0 /* in percent, will not defrag if fragmentation less than specified */ , @rebuildThreshold FLOAT = 30.0 /* in percent, greater than @rebuildThreshold will result in rebuild instead of reorg */ , @executeSQL BIT = 1 /* 1 = execute; 0 = print command only */ , @DATABASE VARCHAR(128) = Null /* Option to specify a database name; null will return all */ , @tableName VARCHAR(4000) = Null -- databaseName.schema.tableName /* Option to specify a table name; null will return all */ , @onlineRebuild BIT = 1 /* 1 = online rebuild; 0 = offline rebuild; only in Enterprise */ , @maxDopRestriction TINYINT = Null /* Option to restrict the number of processors for the operation; only in Enterprise */ , @printCommands BIT = 0 /* 1 = print commands; 0 = do not print commands */ , @printFragmentation BIT = 0 /* 1 = print fragmentation prior to defrag; 0 = do not print */ , @defragDelay CHAR(8) = '00:00:05' /* time to wait between defrag commands */ , @debugMode BIT = 0 /* display some useful comments to help determine if/where issues occur */ AS /********************************************************************************* Name: dba_indexDefrag_sp Author: Michelle Ufford, http://sqlfool.com Purpose: Defrags all indexes for one or more databases Notes: CAUTION: TRANSACTION LOG SIZE MUST BE MONITORED CLOSELY WHEN DEFRAGMENTING. @minFragmentation defaulted to 10%, will not defrag if fragmentation is less than that @rebuildThreshold defaulted to 30% as recommended by Microsoft in BOL; greater than 30% will result in rebuild instead @executeSQL 1 = execute the SQL generated by this proc; 0 = print command only @database Optional, specify specific database name to defrag; If not specified, all non-system databases will be defragged. @tableName Specify if you only want to defrag indexes for a specific table, format = databaseName.schema.tableName; if not specified, all tables will be defragged. @onlineRebuild 1 = online rebuild; 0 = offline rebuild @maxDopRestriction Option to specify a processor limit for index rebuilds @printCommands 1 = print commands to screen; 0 = do not print commands @printFragmentation 1 = print fragmentation to screen; 0 = do not print fragmentation @defragDelay time to wait between defrag commands; gives the server a little time to catch up @debugMode 1 = display debug comments; helps with troubleshooting 0 = do not display debug comments Called by: SQL Agent Job or DBA Date Initials Description ---------------------------------------------------------------------------- 2008-10-27 MFU Initial Release for public consumption 2008-11-17 MFU Added page-count to log table , added @printFragmentation option 2009-03-17 MFU Provided support for centralized execution, , consolidated Enterprise & Standard versions , added @debugMode, @maxDopRestriction , modified LOB and partition logic ********************************************************************************* Exec dbo.dba_indexDefrag_sp @executeSQL = 0 , @minFragmentation = 80 , @printCommands = 1 , @debugMode = 1 , @printFragmentation = 1 , @database = 'AdventureWorks' , @tableName = 'AdventureWorks.Sales.SalesOrderDetail'; *********************************************************************************/ SET NOCOUNT ON; SET XACT_Abort ON; SET Quoted_Identifier ON; BEGIN IF @debugMode = 1 RAISERROR('Dusting off the spiderwebs and starting up...', 0, 42) WITH NoWait; /* Declare our variables */ DECLARE @objectID INT , @databaseID INT , @databaseName NVARCHAR(128) , @indexID INT , @partitionCount BIGINT , @schemaName NVARCHAR(128) , @objectName NVARCHAR(128) , @indexName NVARCHAR(128) , @partitionNumber SMALLINT , @partitions SMALLINT , @fragmentation FLOAT , @pageCount INT , @sqlCommand NVARCHAR(4000) , @rebuildCommand NVARCHAR(200) , @dateTimeStart DATETIME , @dateTimeEnd DATETIME , @containsLOB BIT , @editionCheck BIT , @debugMessage VARCHAR(128) , @updateSQL NVARCHAR(4000) , @partitionSQL NVARCHAR(4000) , @partitionSQL_Param NVARCHAR(1000) , @LOB_SQL NVARCHAR(4000) , @LOB_SQL_Param NVARCHAR(1000); /* Create our temporary tables */ CREATE TABLE #indexDefragList ( databaseID INT , databaseName NVARCHAR(128) , objectID INT , indexID INT , partitionNumber SMALLINT , fragmentation FLOAT , page_count INT , defragStatus BIT , schemaName NVARCHAR(128) Null , objectName NVARCHAR(128) Null , indexName NVARCHAR(128) Null ); CREATE TABLE #databaseList ( databaseID INT , databaseName VARCHAR(128) ); CREATE TABLE #processor ( [INDEX] INT , Name VARCHAR(128) , Internal_Value INT , Character_Value INT ); IF @debugMode = 1 RAISERROR('Beginning validation...', 0, 42) WITH NoWait; /* Just a little validation... */ IF @minFragmentation Not Between 0.00 And 100.0 SET @minFragmentation = 5.0; IF @rebuildThreshold Not Between 0.00 And 100.0 SET @rebuildThreshold = 30.0; IF @defragDelay Not Like '00:[0-5][0-9]:[0-5][0-9]' SET @defragDelay = '00:00:05'; /* Make sure we're not exceeding the number of processors we have available */ INSERT INTO #processor EXECUTE XP_MSVER 'ProcessorCount'; IF @maxDopRestriction IS Not Null And @maxDopRestriction > (SELECT Internal_Value FROM #processor) SELECT @maxDopRestriction = Internal_Value FROM #processor; /* Check our server version; 1804890536 = Enterprise, 610778273 = Enterprise Evaluation, -2117995310 = Developer */ IF (SELECT SERVERPROPERTY('EditionID')) In (1804890536, 610778273, -2117995310) SET @editionCheck = 1 -- supports online rebuilds ELSE SET @editionCheck = 0; -- does not support online rebuilds IF @debugMode = 1 RAISERROR('Grabbing a list of our databases...', 0, 42) WITH NoWait; /* Retrieve the list of databases to investigate */ INSERT INTO #databaseList SELECT database_id , name FROM sys.databases WHERE name = IsNull(@DATABASE, name) And database_id > 4 -- exclude system databases And [STATE] = 0; -- state must be ONLINE IF @debugMode = 1 RAISERROR('Looping through our list of databases and checking for fragmentation...', 0, 42) WITH NoWait; /* Loop through our list of databases */ WHILE (SELECT COUNT(*) FROM #databaseList) > 0 BEGIN SELECT TOP 1 @databaseID = databaseID FROM #databaseList; SELECT @debugMessage = ' working on ' + DB_NAME(@databaseID) + '...'; IF @debugMode = 1 RAISERROR(@debugMessage, 0, 42) WITH NoWait; /* Determine which indexes to defrag using our user-defined parameters */ INSERT INTO #indexDefragList SELECT database_id AS databaseID , QUOTENAME(DB_NAME(database_id)) AS 'databaseName' , [OBJECT_ID] AS objectID , index_id AS indexID , partition_number AS partitionNumber , avg_fragmentation_in_percent AS fragmentation , page_count , 0 AS 'defragStatus' /* 0 = unprocessed, 1 = processed */ , Null AS 'schemaName' , Null AS 'objectName' , Null AS 'indexName' FROM sys.dm_db_index_physical_stats (@databaseID, OBJECT_ID(@tableName), Null , Null, N'Limited') WHERE avg_fragmentation_in_percent >= @minFragmentation And index_id > 0 -- ignore heaps And page_count > 8 -- ignore objects with less than 1 extent OPTION (MaxDop 1); DELETE FROM #databaseList WHERE databaseID = @databaseID; END CREATE CLUSTERED INDEX CIX_temp_indexDefragList ON #indexDefragList(databaseID, objectID, indexID, partitionNumber); SELECT @debugMessage = 'Looping through our list... there''s ' + CAST(COUNT(*) AS VARCHAR(10)) + ' indexes to defrag!' FROM #indexDefragList; IF @debugMode = 1 RAISERROR(@debugMessage, 0, 42) WITH NoWait; /* Begin our loop for defragging */ WHILE (SELECT COUNT(*) FROM #indexDefragList WHERE defragStatus = 0) > 0 BEGIN IF @debugMode = 1 RAISERROR(' Picking an index to beat into shape...', 0, 42) WITH NoWait; /* Grab the most fragmented index first to defrag */ SELECT TOP 1 @objectID = objectID , @indexID = indexID , @databaseID = databaseID , @databaseName = databaseName , @fragmentation = fragmentation , @partitionNumber = partitionNumber , @pageCount = page_count FROM #indexDefragList WHERE defragStatus = 0 ORDER BY fragmentation DESC; IF @debugMode = 1 RAISERROR(' Looking up the specifics for our index...', 0, 42) WITH NoWait; /* Look up index information */ SELECT @updateSQL = N'Update idl Set schemaName = QuoteName(s.name) , objectName = QuoteName(o.name) , indexName = QuoteName(i.name) From #indexDefragList As idl Inner Join ' + @databaseName + '.sys.objects As o On idl.objectID = o.object_id Inner Join ' + @databaseName + '.sys.indexes As i On o.object_id = i.object_id Inner Join ' + @databaseName + '.sys.schemas As s On o.schema_id = s.schema_id Where o.object_id = ' + CAST(@objectID AS VARCHAR(10)) + ' And i.index_id = ' + CAST(@indexID AS VARCHAR(10)) + ' And i.type > 0 And idl.databaseID = ' + CAST(@databaseID AS VARCHAR(10)); EXECUTE SP_EXECUTESQL @updateSQL; /* Grab our object names */ SELECT @objectName = objectName , @schemaName = schemaName , @indexName = indexName FROM #indexDefragList WHERE objectID = @objectID And indexID = @indexID And databaseID = @databaseID; IF @debugMode = 1 RAISERROR(' Grabbing the partition count...', 0, 42) WITH NoWait; /* Determine if the index is partitioned */ SELECT @partitionSQL = 'Select @partitionCount_OUT = Count(*) From ' + @databaseName + '.sys.partitions Where object_id = ' + CAST(@objectID AS VARCHAR(10)) + ' And index_id = ' + CAST(@indexID AS VARCHAR(10)) + ';' , @partitionSQL_Param = '@partitionCount_OUT int OutPut'; EXECUTE SP_EXECUTESQL @partitionSQL, @partitionSQL_Param, @partitionCount_OUT = @partitionCount OUTPUT; IF @debugMode = 1 RAISERROR(' Seeing if there''s any LOBs to be handled...', 0, 42) WITH NoWait; /* Determine if the table contains LOBs */ SELECT @LOB_SQL = ' Select Top 1 @containsLOB_OUT = column_id From ' + @databaseName + '.sys.columns With (NoLock) Where [object_id] = ' + CAST(@objectID AS VARCHAR(10)) + ' And (system_type_id In (34, 35, 99) Or max_length = -1);' /* system_type_id --> 34 = image, 35 = text, 99 = ntext max_length = -1 --> varbinary(max), varchar(max), nvarchar(max), xml */ , @LOB_SQL_Param = '@containsLOB_OUT int OutPut'; EXECUTE SP_EXECUTESQL @LOB_SQL, @LOB_SQL_Param, @containsLOB_OUT = @containsLOB OUTPUT; IF @debugMode = 1 RAISERROR(' Building our SQL statements...', 0, 42) WITH NoWait; /* If there's not a lot of fragmentation, or if we have a LOB, we should reorganize */ IF @fragmentation < @rebuildThreshold Or @containsLOB = 1 Or @partitionCount > 1 BEGIN SET @sqlCommand = N'Alter Index ' + @indexName + N' On ' + @databaseName + N'.' + @schemaName + N'.' + @objectName + N' ReOrganize'; /* If our index is partitioned, we should always reorganize */ IF @partitionCount > 1 SET @sqlCommand = @sqlCommand + N' Partition = ' + CAST(@partitionNumber AS NVARCHAR(10)); END; /* If the index is heavily fragmented and doesn't contain any partitions or LOB's, rebuild it */ IF @fragmentation >= @rebuildThreshold And IsNull(@containsLOB, 0) != 1 And @partitionCount <= 1 BEGIN /* Set online rebuild options; requires Enterprise Edition */ IF @onlineRebuild = 1 And @editionCheck = 1 SET @rebuildCommand = N' Rebuild With (Online = On'; ELSE SET @rebuildCommand = N' Rebuild With (Online = Off'; /* Set processor restriction options; requires Enterprise Edition */ IF @maxDopRestriction IS Not Null And @editionCheck = 1 SET @rebuildCommand = @rebuildCommand + N', MaxDop = ' + CAST(@maxDopRestriction AS VARCHAR(2)) + N')'; ELSE SET @rebuildCommand = @rebuildCommand + N')'; SET @sqlCommand = N'Alter Index ' + @indexName + N' On ' + @databaseName + N'.' + @schemaName + N'.' + @objectName + @rebuildCommand; END; /* Are we executing the SQL? If so, do it */ IF @executeSQL = 1 BEGIN IF @debugMode = 1 RAISERROR(' Executing SQL statements...', 0, 42) WITH NoWait; /* Grab the time for logging purposes */ SET @dateTimeStart = GETDATE(); EXECUTE SP_EXECUTESQL @sqlCommand; SET @dateTimeEnd = GETDATE(); /* Log our actions */ INSERT INTO dbo.dba_indexDefragLog ( databaseID , databaseName , objectID , objectName , indexID , indexName , partitionNumber , fragmentation , page_count , dateTimeStart , durationSeconds ) SELECT @databaseID , @databaseName , @objectID , @objectName , @indexID , @indexName , @partitionNumber , @fragmentation , @pageCount , @dateTimeStart , DATEDIFF(SECOND, @dateTimeStart, @dateTimeEnd); /* Just a little breather for the server */ WAITFOR Delay @defragDelay; /* Print if specified to do so */ IF @printCommands = 1 PRINT N'Executed: ' + @sqlCommand; END ELSE /* Looks like we're not executing, just printing the commands */ BEGIN IF @debugMode = 1 RAISERROR(' Printing SQL statements...', 0, 42) WITH NoWait; IF @printCommands = 1 PRINT IsNull(@sqlCommand, 'error!'); END IF @debugMode = 1 RAISERROR(' Updating our index defrag status...', 0, 42) WITH NoWait; /* Update our index defrag list so we know we've finished with that index */ UPDATE #indexDefragList SET defragStatus = 1 WHERE databaseID = @databaseID And objectID = @objectID And indexID = @indexID And partitionNumber = @partitionNumber; END /* Do we want to output our fragmentation results? */ IF @printFragmentation = 1 BEGIN IF @debugMode = 1 RAISERROR(' Displaying fragmentation results...', 0, 42) WITH NoWait; SELECT databaseID , databaseName , objectID , objectName , indexID , indexName , fragmentation , page_count FROM #indexDefragList; END; /* When everything is said and done, make sure to get rid of our temp table */ DROP TABLE #indexDefragList; DROP TABLE #databaseList; DROP TABLE #processor; IF @debugMode = 1 RAISERROR('DONE! Thank you for taking care of your indexes! :)', 0, 42) WITH NoWait; SET NOCOUNT OFF; RETURN 0 END Go
Thanks to my beta testers, @scoinva, @davidmtate, @jdanton, and @SuperCoolMoss!
Special thanks to SCM for keeping on me to finish this.
Happy Defragging!
Michelle
Source: http://sqlfool.com/2009/03/automated-index-defrag-script/
Index Clean-Up Scripts
January 20, 2009 by Michelle Ufford · 12 Comments
Filed under: Performance & Tuning, Syndication, T-SQL Scripts
Filed under: Performance & Tuning, Syndication, T-SQL Scripts
I’ve been spending a lot of time lately looking at indexing in my production environments… dropping un-used ones, adding missing ones, and fine-tuning the ones I already have. I thought I’d share some of the scripts I’ve been using to accomplish this.
Here’s the script I use to find any un-used indexes. This relies heavily on the sys.dm_db_index_usage_stats DMV (2005+). This query will also return the SQL statements needed to drop the indexes for convenience. This does NOT mean you should necessarily drop the index. This is only a guide and a starting point; only you know how your application is used and whether SQL Server’s recommendations make sense.
Un-Used Indexes Script
DECLARE @dbid INT , @dbName VARCHAR(100); SELECT @dbid = DB_ID() , @dbName = DB_NAME(); WITH partitionCTE (OBJECT_ID, index_id, row_count, partition_count) AS ( SELECT [OBJECT_ID] , index_id , SUM([ROWS]) AS 'row_count' , COUNT(partition_id) AS 'partition_count' FROM sys.partitions GROUP BY [OBJECT_ID] , index_id ) SELECT OBJECT_NAME(i.[OBJECT_ID]) AS objectName , i.name , CASE WHEN i.is_unique = 1 THEN 'UNIQUE ' ELSE '' END + i.type_desc AS 'indexType' , ddius.user_seeks , ddius.user_scans , ddius.user_lookups , ddius.user_updates , cte.row_count , CASE WHEN partition_count > 1 THEN 'yes' ELSE 'no' END AS 'partitioned?' , CASE WHEN i.type = 2 And i.is_unique_constraint = 0 THEN 'Drop Index ' + i.name + ' On ' + @dbName + '.dbo.' + OBJECT_NAME(ddius.[OBJECT_ID]) + ';' WHEN i.type = 2 And i.is_unique_constraint = 1 THEN 'Alter Table ' + @dbName + '.dbo.' + OBJECT_NAME(ddius.[OBJECT_ID]) + ' Drop Constraint ' + i.name + ';' ELSE '' END AS 'SQL_DropStatement' FROM sys.indexes AS i INNER Join sys.dm_db_index_usage_stats ddius ON i.OBJECT_ID = ddius.OBJECT_ID And i.index_id = ddius.index_id INNER Join partitionCTE AS cte ON i.OBJECT_ID = cte.OBJECT_ID And i.index_id = cte.index_id WHERE ddius.database_id = @dbid ORDER BY (ddius.user_seeks + ddius.user_scans + ddius.user_lookups) ASC , user_updates DESC;
This next script relies on several DMV’s (2005+) that identify missing indexes. While this is good information, the index recommendations do not always make sense and/or sometimes overlap. Also, these DMV’s store data since the SQL Server was last restarted, so if it’s been a while since your server was rebooted, this data may be out of date. This script also provides a SQL statement, in case you do decide to create the index, but it doesn’t take into consideration advanced parameters (i.e. sort_in_tempDB, Online, MaxDop, etc.) and only provides a basic create statement. Nonetheless, it’s another good starting point.
Missing Index Script
SELECT t.name AS 'affected_table' , 'Create NonClustered Index IX_' + t.name + '_missing_' + CAST(ddmid.index_handle AS VARCHAR(10)) + ' On ' + ddmid.STATEMENT + ' (' + IsNull(ddmid.equality_columns,'') + CASE WHEN ddmid.equality_columns IS Not Null And ddmid.inequality_columns IS Not Null THEN ',' ELSE '' END + IsNull(ddmid.inequality_columns, '') + ')' + IsNull(' Include (' + ddmid.included_columns + ');', ';' ) AS sql_statement , ddmigs.user_seeks , ddmigs.user_scans , CAST((ddmigs.user_seeks + ddmigs.user_scans) * ddmigs.avg_user_impact AS INT) AS 'est_impact' , ddmigs.last_user_seek FROM sys.dm_db_missing_index_groups AS ddmig INNER Join sys.dm_db_missing_index_group_stats AS ddmigs ON ddmigs.group_handle = ddmig.index_group_handle INNER Join sys.dm_db_missing_index_details AS ddmid ON ddmig.index_handle = ddmid.index_handle INNER Join sys.tables AS t ON ddmid.OBJECT_ID = t.OBJECT_ID WHERE ddmid.database_id = DB_ID() And CAST((ddmigs.user_seeks + ddmigs.user_scans) * ddmigs.avg_user_impact AS INT) > 100 ORDER BY CAST((ddmigs.user_seeks + ddmigs.user_scans) * ddmigs.avg_user_impact AS INT) DESC;
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