SQL Fool » T-SQL Scripts

Index Defrag Script Updates – Beta Testers Needed

Michelle Ufford — Tue, 26 Jan 2010 21:15:37 +0000

Update: Wow! I’ve received a ton of responses to my request for beta testers. Thank you all! The SQL Community is really amazing. I’ll hopefully have the new version online in just a few days.

Over the last few months, I’ve received many great comments and suggestions regarding my Index Defrag Script v3.0. I’ve just recently had time to implement most of these suggestions, plus some other things that I thought would be useful.

Here’s some of what you can look forward to shortly:

Probably the single most requested feature, the new version of the script allows you to set a time limit for index defrags.
There’s now a static table for managing the status of index defrags. This way, when your time limit is reached, you can pick up where you left off the next day, without the need to rescan indexes.
There’s now an option to prioritize defrags by range scan counts, fragmentation level, or page counts.
For those using partitioning, there is now an option to exclude the right-most populated partition from defrags (in theory, the one you’re writing to in a sliding-window scenario).
Options such as page count limits and SORT_IN_TEMPDB are now parameterized.
I’ve enhanced error logging.
… and more!

Right now, I’m looking for a few folks who are willing to beta test the script. If you’re interested, please send me an e-mail at michelle at sqlfool dot com with the editions of SQL Server you can test this on (i.e. 2005 Standard, 2008 Enterprise, etc.).

Thank you!

Monitoring Process for Performance Counters

Michelle Ufford — Wed, 16 Sep 2009 17:19:12 +0000

Recently I needed to create a process to monitor performance counters over a short period of time. We were going to implement a change and we wanted to compare performance before and after to see if there was any impact.

To do this, I first created a couple of tables. One table is used to actually store the monitored values. The second table is used for configuration; you insert only the counters you want to monitor.

/* Create the table to store our logged perfmon counters */
CREATE TABLE dbo.dba_perfCounterMonitor
(
      capture_id    INT IDENTITY(1,1)   Not Null
    , captureDate   SMALLDATETIME       Not Null
    , objectName    NVARCHAR(128)       Not Null
    , counterName   NVARCHAR(128)       Not Null
    , instanceName  NVARCHAR(128)       Not Null
    , VALUE         FLOAT(6)            Not Null
    , valueType     NVARCHAR(10)        Not Null
 
    CONSTRAINT PK_dba_perfCounterMonitor
        PRIMARY KEY CLUSTERED(capture_id)
);
 
/* Create the table that controls which counters we're going to monitor */
CREATE TABLE dbo.dba_perfCounterMonitorConfig
(
      objectName    NVARCHAR(128)   Not Null
    , counterName   NVARCHAR(128)   Not Null
    , instanceName  NVARCHAR(128)   Null
);

If you leave the instanceName NULL in the config table, it’ll monitor all instances. Now we’re going to insert some sample performance counters into the config table. The counters you’re interested in can, and likely will, vary.

/* Insert some perfmon counters to be monitored */
INSERT INTO dbo.dba_perfCounterMonitorConfig
SELECT 'SQLServer:Buffer Manager', 'Page Life Expectancy', Null UNION All
SELECT 'SQLServer:Locks', 'Lock Requests/sec', Null UNION All
SELECT 'SQLServer:Locks', 'Lock Waits/sec', Null UNION All
SELECT 'SQLServer:Locks', 'Lock Wait Time (ms)', Null UNION All
SELECT 'SQLServer:Buffer Manager', 'Page reads/sec', Null UNION All
SELECT 'SQLServer:Buffer Manager', 'Page writes/sec', Null UNION All
SELECT 'SQLServer:Buffer Manager', 'Buffer cache hit ratio', Null UNION All
SELECT 'SQLServer:Databases', 'Transactions/sec', 'AdventureWorks' UNION All
SELECT 'SQLServer:General Statistics', 'Processes blocked', Null;

Now let’s create our proc. This proc will run for a specified time period and will *average* the counters over that time. I personally take snapshots every 15 seconds for 4 minutes; I have a scheduled task that runs this every 5 minutes. It’s not perfect, but it gives me a good idea of what’s happening on the server.

CREATE PROCEDURE dbo.dba_perfCounterMonitor_sp
 
        /* Declare Parameters */
          @samplePeriod    INT      =  240  /* how long to sample, in seconds */
        , @sampleRate      CHAR(8)  =  '00:00:15'  /* how frequently to sample, in seconds */
        , @displayResults  BIT      =  0  /* display the results when done */
AS
/*********************************************************************************
    Name:       dba_perfCounterMonitor_sp
 
    Author:     Michelle Ufford, http://sqlfool.com
 
    Purpose:    Monitors performance counters.  Uses the dba_perfCounterMonitorConfig
                table to manage which perf counters to monitor.  
 
                @samplePeriod - specifies how long the process will try to monitor
                                performance counters; in seconds.
 
                @sampleRate - how long inbetween samples; in seconds.
 
                The average values over sample period is then logged to the
                dba_perfCounterMonitor table.
 
    Notes:      There are 3 basic types of performance counter calculations:
 
                Value/Base: these calculations require 2 counters. The value 
                            counter (cntr_type = 537003264) has to be divided 
                            by the base counter (cntr_type = 1073939712).
 
                Per Second: these counters are store cumulative values; the
                            value must be compared at 2 different times to
                            calculate the difference (cntr_type = 537003264).
 
                Point In Time:  these counters show what the value of the
                                counter is at the current point-in-time 
                                (cntr_type = 65792).  No calculation is 
                                necessary to derive the value.
 
    Called by:  DBA
 
    Date        User    Description
    ----------------------------------------------------------------------------
    2009-09-04  MFU     Initial Release
*********************************************************************************
    Exec dbo.dba_perfCounterMonitor_sp
          @samplePeriod     = 60
        , @sampleRate       = '00:00:01'
        , @displayResults   = 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;
 
BEGIN
 
    /* Declare Variables */
    DECLARE @startTime DATETIME
        , @endTime DATETIME
        , @iteration INT;
 
    SELECT @startTime = GETDATE()
        , @iteration = 1;
 
    DECLARE @samples TABLE
    (
          iteration     INT             Not Null
        , objectName    NVARCHAR(128)   Not Null
        , counterName   NVARCHAR(128)   Not Null
        , instanceName  NVARCHAR(128)   Not Null
        , cntr_value    FLOAT           Not Null
        , base_value    FLOAT           Null
        , cntr_type     BIGINT          Not Null
    );
 
    BEGIN Try
 
        /* Start a new transaction */
        BEGIN TRANSACTION;
 
        /* Grab all of our counters */
        INSERT INTO @samples
        SELECT @iteration
            , RTRIM(dopc.OBJECT_NAME)
            , RTRIM(dopc.counter_name)
            , RTRIM(dopc.instance_name)
            , RTRIM(dopc.cntr_value)
            , (SELECT cntr_value FROM sys.dm_os_performance_counters AS dopc1
                WHERE dopc1.OBJECT_NAME = pcml.objectName
                And dopc1.counter_name = pcml.counterName + ' base'
                And dopc1.instance_name = IsNull(pcml.instanceName, dopc.instance_name))
            , dopc.cntr_type
        FROM sys.dm_os_performance_counters AS dopc
        Join dbo.dba_perfCounterMonitorConfig AS pcml
            ON dopc.OBJECT_NAME = pcml.objectName
                And dopc.counter_name = pcml.counterName
                And dopc.instance_name = IsNull(pcml.instanceName, dopc.instance_name);
 
        /* During our sample period, grab our counter values and store the results */
        WHILE GETDATE() < DATEADD(SECOND, @samplePeriod, @startTime)
        BEGIN
 
            SET @iteration = @iteration + 1;
 
            INSERT INTO @samples
            SELECT @iteration
                , RTRIM(dopc.OBJECT_NAME)
                , RTRIM(dopc.counter_name)
                , RTRIM(dopc.instance_name)
                , dopc.cntr_value
                , (SELECT cntr_value FROM sys.dm_os_performance_counters AS dopc1
                    WHERE dopc1.OBJECT_NAME = pcml.objectName
                    And dopc1.counter_name = pcml.counterName + ' base'
                    And dopc1.instance_name = IsNull(pcml.instanceName, dopc.instance_name))
                , dopc.cntr_type
            FROM sys.dm_os_performance_counters AS dopc
            Join dbo.dba_perfCounterMonitorConfig AS pcml
                ON dopc.OBJECT_NAME = pcml.objectName
                    And dopc.counter_name = pcml.counterName
                    And dopc.instance_name = IsNull(pcml.instanceName, dopc.instance_name);
 
            /* Wait for a small delay */
            WAITFOR Delay @sampleRate;
 
        END;
 
        /* Grab our end time for calculations */
        SET @endTime = GETDATE();
 
        /* Store the average of our point-in-time counters */
        INSERT INTO dbo.dba_perfCounterMonitor 
        (
			  captureDate
			, objectName
			, counterName
			, instanceName
			, VALUE
			, valueType
		) 
		SELECT @startTime
		    , objectName
		    , counterName
		    , instanceName
		    , AVG(cntr_value)
		    , 'value'
		FROM @samples
		WHERE cntr_type = 65792
		GROUP BY objectName
		    , counterName
		    , instanceName;
 
        /* Store the average of the value vs the base for cntr_type = 537003264 */
        INSERT INTO dbo.dba_perfCounterMonitor 
        (
			  captureDate
			, objectName
			, counterName
			, instanceName
			, VALUE
			, valueType
		) 
		SELECT @startTime
		    , objectName
		    , counterName
		    , instanceName
		    , AVG(cntr_value)/AVG(IsNull(base_value, 1))
		    , 'percent'
		FROM @samples
		WHERE cntr_type = 537003264
		GROUP BY objectName
		    , counterName
		    , instanceName;
 
        /* Compare the first and last values for our cumulative, per-second counters */
        INSERT INTO dbo.dba_perfCounterMonitor 
        (
			  captureDate
			, objectName
			, counterName
			, instanceName
			, VALUE
			, valueType
		) 
		SELECT @startTime
		    , objectName
		    , counterName
		    , instanceName
		    , (MAX(cntr_value) - MIN(cntr_value)) / DATEDIFF(SECOND, @startTime, @endTime)
		    , 'value'
		FROM @samples
		WHERE cntr_type = 272696576
        GROUP BY objectName
		    , counterName
		    , instanceName;
 
        /* Should we display the results of our most recent execution?  */
        IF @displayResults = 1
            SELECT captureDate
                , objectName
                , counterName
                , instanceName
                , VALUE
                , valueType
            FROM dbo.dba_perfCounterMonitor WITH (NoLock)
            WHERE captureDate = CAST(@startTime AS SMALLDATETIME)
            ORDER BY objectName
                , counterName
                , instanceName;
 
        /* If you have an open transaction, commit it */
        IF @@TRANCOUNT > 0
            COMMIT TRANSACTION;
 
    END Try
    BEGIN Catch
 
        /* Whoops, there was an error... rollback! */
        IF @@TRANCOUNT > 0
            ROLLBACK TRANSACTION;
 
        /* Return an error message and log it */
        EXECUTE dbo.dba_logError_sp;
 
    END Catch;
 
    SET NOCOUNT OFF;
    RETURN 0;
END
Go

Like I said, it’s not perfect, but it gets the job done.

Getting an error about dba_logError_sp? Take a look at my error handling proc.

Find Recently Executed Stored Procedures

Michelle Ufford — Mon, 03 Aug 2009 15:14:39 +0000

This past weekend, we had an issue where replication fell far behind on one of our databases. The replicated database is used for all sorts of reporting, so the immediate need was to identify processes that may have been affected by the incomplete data.

Now, there’s hundreds of stored procedures that reference the affected database; the trick is finding out which ones are relevant. To do this, I used the sys.dm_exec_query_stats DMV. This does two things for me. One, it shows me a list of stored procedures in cache, meaning they’ve been executed relatively recently and are probably relevant to the search. Secondly, it shows me the last execution time, which in some cases may have been before the issue, meaning I do not need to worry about re-running those processes.

Here’s the query I used:

SELECT DB_NAME(dest.[dbid]) AS 'databaseName'
    , OBJECT_NAME(dest.objectid, dest.[dbid]) AS 'procName'
    , MAX(deqs.last_execution_time) AS 'last_execution'
FROM sys.dm_exec_query_stats AS deqs
Cross Apply sys.dm_exec_sql_text(deqs.sql_handle) AS dest
WHERE dest.[TEXT] Like '%yourTableName%' -- replace
    And dest.[dbid] IS Not Null  -- exclude ad-hocs
GROUP BY DB_NAME(dest.[dbid])
    , OBJECT_NAME(dest.objectid, dest.[dbid])
ORDER BY databaseName
    , procName
OPTION (MaxDop 1);

This will return results similar to:

databaseName         procName                       last_execution
-------------------- ------------------------------ -----------------------
AdventureWorks       ufnGetProductListPrice         2009-08-03 09:57:25.390
AdventureWorksDW     DimProductCategoryGet_sp       2009-08-03 09:59:05.820
AdventureWorksDW     DimProductGet_sp               2009-08-03 09:58:38.370

I want to stress that this is *not* a list of all referencing objects, but rather a list of recently executed stored procedures that are still in memory. This list may not be accurate if your cache has recently been flushed or if you’ve recently rebooted your server.

Index Defrag Script Update

Michelle Ufford — Thu, 09 Jul 2009 16:45:02 +0000

A couple of people pointed out to me that the stats rebuild feature in my defrag script will only complete for one database. Whoopsies! I’ve fixed the bug and updated the script in my previous post, so if you’re using my defrag script, please update it. Thanks to Derick and SuperCoolMoss for letting me know about the bug.

I’ve also received a couple of other requests for feature enhancements. I’m currently swamped at work and outside of work, but as soon as I get time, I will release the latest version. Realistically, it’ll probably be sometime after summer ends.

Thank you to everyone for their comments and suggestions!

Index Defrag Script, v3.0

Michelle Ufford — Wed, 24 Jun 2009 00:37:24 +0000

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

sp_WhoIsActive

Michelle Ufford — Fri, 29 May 2009 02:20:57 +0000

For those who attended the webcast I did with Brent Ozar today, “Getting Started With SQL Server Management Studio,” here’s the link to Adam Machanic’s excellent sp_WhoIsActive stored proc:

http://sqlblog.com/blogs/adam_machanic/archive/2009/03/30/who-is-active-v8-40-now-with-delta-power.aspx

Thanks for attending!

Page Internals – Investigation Proc

Michelle Ufford — Wed, 06 May 2009 19:01:11 +0000

As many of you know, I like to crawl around in page internals in my free time. It can be very enlightening, or just a good check to make sure that what you think is happening, is actually happening. To help with this process, I’ve created myself a little stored procedure that I can simply pass a few parameters to and have it return the page data for me. So for those who don’t have anything better to do who are as interested in page internals as I am, here’s my proc:

CREATE PROCEDURE dbo.dba_viewPageData_sp
 
        /* Declare Parameters */
          @databaseName VARCHAR(128)
        , @tableName    VARCHAR(128)    = Null -- database.schema.tableName
        , @indexName    VARCHAR(128)    = Null
        , @fileNumber   INT             = Null
        , @pageNumber   INT             = Null
        , @printOption  INT             = 3    -- 0, 1, 2, or 3
        , @pageType     CHAR(4)         = 'Leaf' -- Leaf, Root, or IAM
 
AS
/*********************************************************************************
    Name:       dba_viewPageData_sp
 
    Author:     Michelle Ufford
 
    Purpose:    Retrieves page data for the specified table/page.
 
    Notes:      Can pass either the table name or the pageID, but must pass one, or
                you'll end up with no results. 
                If the table name is passed, it will return the first page.
 
        @tableName must be '..' in order to
            function correctly for cross-database joins.  
 
        @printOption can be one of following values:
            0 - print just the page header
            1 - page header plus per-row hex dumps and a dump of the page slot array
            2 - page header plus whole page hex dump
            3 - page header plus detailed per-row interpretation
 
        Page Options borrowed from: 
        https://blogs.msdn.com/sqlserverstorageengine/archive/2006/06/10/625659.aspx
 
        @pageType must be one of the following values:
            Leaf - returns the first page of the leaf level of your index or heap
            Root - returns the root page of your index
            IAM - returns the index allocation map chain for your index or heap
 
        Conversions borrowed from:
        http://sqlskills.com/blogs/paul/post/Inside-The-Storage-Engine-
        sp_AllocationMetadata-putting-undocumented-system-catalog-views-to-work.aspx
 
    Called by:  DBA
 
    Date        User    Description
    ----------------------------------------------------------------------------
    2009-05-06  MFU     Initial release for public consumption
*********************************************************************************
    Exec dbo.dba_viewPageData_sp
          @databaseName = 'AdventureWorks'
        , @tableName    = 'AdventureWorks.Sales.SalesOrderDetail'
        , @indexName    = 'IX_SalesOrderDetail_ProductID'
        --, @fileNumber   = 1
        --, @pageNumber   = 38208
        , @printOption  = 3
        , @pageType     = 'Root';
*********************************************************************************/
 
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;
 
BEGIN
 
    DECLARE @fileID         INT
        , @pageID           INT
        , @sqlStatement     NVARCHAR(1200)
        , @sqlParameters    NVARCHAR(255)
        , @errorMessage     VARCHAR(100);
 
    BEGIN Try
 
        IF @fileNumber IS Null And @pageNumber IS Null And @tableName IS Null
        BEGIN
            SET @errorMessage = 'You must provide either a file/page number, or a table name!';
            RAISERROR(@errorMessage, 16, 1);
        END;
 
        IF @pageType Not In ('Leaf', 'Root', 'IAM')
        BEGIN
            SET @errorMessage = 'You have entered an invalid page type; valid options are "Leaf", "Root", or "IAM"';
            RAISERROR(@errorMessage, 16, 1);
        END;
 
        IF @fileNumber IS Null Or @pageNumber IS Null
        BEGIN
 
            SET @sqlStatement = 
            CASE WHEN @pageType = 'Leaf' THEN
                'Select Top 1 @p_fileID = Convert (varchar(6), Convert (int, 
                    SubString (au.first_page, 6, 1) +
                    SubString (au.first_page, 5, 1)))
                , @p_pageID = Convert (varchar(20), Convert (int, 
                     SubString (au.first_page, 4, 1) +
                     SubString (au.first_page, 3, 1) +
                     SubString (au.first_page, 2, 1) +
                     SubString (au.first_page, 1, 1)))'
            WHEN @pageType = 'Root' THEN
                'Select Top 1 @p_fileID = Convert (varchar(6), Convert (int, 
                    SubString (au.root_page, 6, 1) +
                    SubString (au.root_page, 5, 1)))
                , @p_pageID = Convert (varchar(20), Convert (int, 
                     SubString (au.root_page, 4, 1) +
                     SubString (au.root_page, 3, 1) +
                     SubString (au.root_page, 2, 1) +
                     SubString (au.root_page, 1, 1)))'
            WHEN @pageType = 'IAM' THEN
                'Select Top 1 @p_fileID = Convert (varchar(6), Convert (int, 
                    SubString (au.first_iam_page, 6, 1) +
                    SubString (au.first_iam_page, 5, 1)))
                , @p_pageID = Convert (varchar(20), Convert (int, 
                     SubString (au.first_iam_page, 4, 1) +
                     SubString (au.first_iam_page, 3, 1) +
                     SubString (au.first_iam_page, 2, 1) +
                     SubString (au.first_iam_page, 1, 1)))'
            END + 
            'From ' + QUOTENAME(PARSENAME(@databaseName, 1)) + '.sys.indexes AS i
            Join ' + QUOTENAME(PARSENAME(@databaseName, 1)) + '.sys.partitions AS p
                On i.[object_id] = p.[object_id]
                And i.index_id = p.index_id
            Join ' + QUOTENAME(PARSENAME(@databaseName, 1)) + '.sys.system_internals_allocation_units AS au
                On p.hobt_id = au.container_id
            Where p.[object_id] = Object_ID(@p_tableName)
                And au.first_page > 0x000000000000 ' 
                + CASE WHEN @indexName IS Null 
                    THEN ';' 
                    ELSE 'And i.name = @p_indexName;' END;
 
            SET @sqlParameters = '@p_tableName varchar(128)
                                , @p_indexName varchar(128)
                                , @p_fileID int OUTPUT
                                , @p_pageID int OUTPUT';
 
            EXECUTE SP_EXECUTESQL @sqlStatement
                        , @sqlParameters
                        , @p_tableName = @tableName
                        , @p_indexName = @indexName
                        , @p_fileID = @fileID OUTPUT
                        , @p_pageID = @pageID OUTPUT;
 
            END
            ELSE
            BEGIN
                SELECT @fileID = @fileNumber
                    , @pageID = @pageNumber;
            END;
 
        DBCC TraceOn (3604);
        DBCC Page (@databaseName, @fileID, @pageID, @printOption);
        DBCC TraceOff (3604);
 
    END Try
    BEGIN Catch
 
        PRINT @errorMessage;
 
    END Catch;
 
    SET NOCOUNT OFF;
    RETURN 0;
END
Go

This proc does have cross-database support, i.e. you can install it in your DBA database and use it to investigate data in other databases. Here’s an example…

    EXEC dbo.dba_viewPageData_sp
          @databaseName = 'AdventureWorks'
        , @tableName    = 'AdventureWorks.Sales.SalesOrderDetail'
        , @indexName    = 'IX_SalesOrderDetail_ProductID';

… will return a nice data page:

DBCC execution completed. If DBCC printed error messages, contact your system administrator.
 
PAGE: (1:11000)
 
BUFFER:
 
BUF @0x0391F140
 
bpage = 0x0C0C0000                   bhash = 0x00000000                   bpageno = (1:11000)
bdbid = 7                            breferences = 0                      bUse1 = 35177
bstat = 0x1c00009                    blog = 0x21212159                    bnext = 0x00000000

[waits for the "oohs" and "aahs" to subside...]

I also give you the option to specify a specific page, in case you want to follow the page trail (i.e. m_nextPage). I’m not really providing support for partitions, although I do have a little dirty piece of code to return a hobt with data if possible (i.e. “first_page > 0×000000000000″).

Update: Special thanks to Jeremiah Peschka and Adam Machanic for showing me
QUOTENAME(PARSENAME(@databaseName, 1))!

Also, thanks to Paul Randal for his excellent blog posts on this very topic! Check out his blog post on DBCC Page. The conversion code was borrowed from his sp_AllocationMetadata proc.

Update 2: I’ve made some quick changes based on some feedback from Twitter. Thanks for the suggestions and hopefully you enjoy the updates.

Happy crawling!

A Look at Missing Indexes

Michelle Ufford — Tue, 28 Apr 2009 16:30:55 +0000

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 []
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

Michelle Ufford — Wed, 25 Mar 2009 13:34:13 +0000

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/

Find Missing Indexes in Stored Procs with T-SQL

Michelle Ufford — Mon, 02 Mar 2009 16:11:37 +0000

This post should probably be called “The Power of Twitter.” I’ve said it before, I’ll say it again: I love Twitter. I mostly follow SQL Server people, so it’s become a great source of new information and help when I feel like banging my head against the wall when I get stumped.

So last week, Jonathan Kehayias (@jmkehayias) posted a link to a missing index script on the MSDN forums. Jonathan’s script is modified from something he put together for a question posed by Jeremiah Peschka (@peschkaj).

Jonathan’s script intrigued me. I’d never tried to search a query plan’s XML before, and it certainly presents some interesting possibilities. After dealing with a missing index in production a few weeks ago (caused by an index change), I thought it’d be a great idea to put a regular monitor in place.

Everything was going well until I ran into a problem where I couldn’t get the proc name returned. The results spanned numerous databases; I had the object_id and database_id, but I wanted to store the proc name instead. I tried several different methods, including sp_msforeachdb and sp_executeSQL, and while I had a working solution, it was a little more clunky than I liked. So I asked my awesome followers on Twitter for any tips and within minutes I had half a dozen responses. In the end, @MladenPrajdic solved my problem with a pretty simple solution: put ‘Use ?;’ at the start of my sp_msforeachdb statement. Thanks again, Mladen!

I’ve now had this process running on my server for a few days now, with good success. The stored procedure below will return the database name, proc name, and query plan XML for any stored proc with a missing index. This is a centralized proc that will store the results in a table for later action. If you click on the XML, you should see the actual query plan with the missing index details. Because this looks at cached query plans, your best bet is to run it fairly regularly (maybe daily) to increase your chances of catching any problem procs.

/* Create a stored procedure skeleton */
IF OBJECTPROPERTY(OBJECT_ID('dbo.dba_missingIndexStoredProc_sp'), N'IsProcedure') IS Null
BEGIN
    EXECUTE ('Create Procedure dbo.dba_missingIndexStoredProc_sp As Print ''Hello World!''')
    RAISERROR('Procedure dba_missingIndexStoredProc_sp created.', 10, 1);
END;
Go
 
/* Drop our table if it already exists */
IF Exists(SELECT OBJECT_ID FROM sys.tables WHERE [name] = N'dba_missingIndexStoredProc')
BEGIN
    DROP TABLE dbo.dba_missingIndexStoredProc
    PRINT 'dba_missingIndexStoredProc table dropped!';
END
 
/* Create our table */
CREATE TABLE dbo.dba_missingIndexStoredProc
(
      missingIndexSP_id INT IDENTITY(1,1)   Not Null
    , databaseName      VARCHAR(128)        Not Null
    , databaseID        INT                 Not Null
    , objectName        VARCHAR(128)        Not Null
    , objectID          INT                 Not Null
    , query_plan        xml                 Not Null
    , executionDate     SMALLDATETIME       Not Null
 
    CONSTRAINT PK_missingIndexStoredProc
        PRIMARY KEY CLUSTERED(missingIndexSP_id)
);
 
PRINT 'dba_missingIndexStoredProc Table Created';
 
/* Configure our settings */
SET ANSI_Nulls ON;
SET Quoted_Identifier ON;
Go
 
ALTER PROCEDURE dbo.dba_missingIndexStoredProc_sp
 
        /* Declare Parameters */
            @lastExecuted_inDays    INT = 7
          , @minExecutionCount      INT = 7
          , @logResults             BIT = 1
          , @displayResults         BIT = 0
 
AS
/*********************************************************************************
    Name:       dba_missingIndexStoredProc_sp
 
    Author:     Michelle Ufford, http://sqlfool.com
 
    Purpose:    Retrieves stored procedures with missing indexes in their
                cached query plans.
 
                @lastExecuted_inDays = number of days old the cached query plan
                                       can be to still appear in the results;
                                       the HIGHER the number, the longer the
                                       execution time.
 
                @minExecutionCount = minimum number of executions the cached
                                     query plan can have to still appear 
                                     in the results; the LOWER the number,
                                     the longer the execution time.
 
                @logResults = store results in dba_missingIndexStoredProc
 
                @displayResults = return results to the caller
 
    Notes:      This is not 100% guaranteed to catch all missing indexes in
                a stored procedure.  It will only catch it if the stored proc's
                query plan is still in cache.  Run regularly to help minimize
                the chance of missing a proc.
 
    Called by:  DBA and/or SQL Agent Job
 
    Date        User    Description
    ----------------------------------------------------------------------------
    2009-03-02  MFU     Initial Release for public consumption
*********************************************************************************
    Exec dbo.dba_missingIndexStoredProc_sp
          @lastExecuted_inDays  = 30
        , @minExecutionCount    = 5
        , @logResults           = 1
        , @displayResults       = 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;
 
BEGIN
 
    /* Declare Variables */
    DECLARE @currentDateTime SMALLDATETIME;
 
    SET @currentDateTime = GETDATE();
 
    DECLARE @plan_handles TABLE
    (
        plan_handle     VARBINARY(64)   Not Null
    );
 
    CREATE TABLE #missingIndexes
    (
          databaseID    INT             Not Null
        , objectID      INT             Not Null
        , query_plan    xml             Not Null
 
        CONSTRAINT PK_temp_missingIndexes PRIMARY KEY CLUSTERED
        (
            databaseID, objectID
        )
    );
 
    BEGIN Try
 
        /* Perform some data validation */
        IF @logResults = 0 And @displayResults = 0
        BEGIN
 
            /* Log the fact that there were open transactions */
            EXECUTE dbo.dba_logError_sp
                  @errorType            = 'app'
                , @app_errorProcedure   = 'dba_missingIndexStoredProc_sp'
                , @app_errorMessage     = '@logResults = 0 and @displayResults = 0; no action taken, exiting stored proc.'
                , @forceExit            = 1
                , @returnError          = 1;  
 
        END;
 
        BEGIN TRANSACTION;
 
        /* Retrieve distinct plan handles to minimize dm_exec_query_plan lookups */
        INSERT INTO @plan_handles
        SELECT DISTINCT plan_handle
        FROM sys.dm_exec_query_stats
        WHERE last_execution_time > DATEADD(DAY, -@lastExecuted_inDays, @currentDateTime)
            And execution_count > @minExecutionCount;
 
        WITH xmlNameSpaces (
            DEFAULT 'http://schemas.microsoft.com/sqlserver/2004/07/showplan'
        )
 
        /* Retrieve our query plan's XML if there's a missing index */
        INSERT INTO #missingIndexes
        SELECT deqp.[dbid]
            , deqp.objectid
            , deqp.query_plan 
        FROM @plan_handles AS ph
        Cross Apply sys.dm_exec_query_plan(ph.plan_handle) AS deqp 
        WHERE deqp.query_plan.exist('//MissingIndex') = 1
            And deqp.objectid IS Not Null;
 
        /* Do we want to store the results of our process? */
        IF @logResults = 1
        BEGIN
            INSERT INTO dbo.dba_missingIndexStoredProc
            EXECUTE sp_msForEachDB 'Use ?; 
                                    Select ''?''
                                        , mi.databaseID
                                        , Object_Name(o.object_id)
                                        , o.object_id
                                        , mi.query_plan
                                        , GetDate()
                                    From sys.objects As o 
                                    Join #missingIndexes As mi 
                                        On o.object_id = mi.objectID 
                                    Where databaseID = DB_ID();';
 
        END
        /* We're not logging it, so let's display it */
        ELSE
        BEGIN
            EXECUTE sp_msForEachDB 'Use ?; 
                                    Select ''?''
                                        , mi.databaseID
                                        , Object_Name(o.object_id)
                                        , o.object_id
                                        , mi.query_plan
                                        , GetDate()
                                    From sys.objects As o 
                                    Join #missingIndexes As mi 
                                        On o.object_id = mi.objectID 
                                    Where databaseID = DB_ID();';
        END;
 
        /* See above; this part will only work if we've 
           logged our data. */
        IF @displayResults = 1 And @logResults = 1
        BEGIN
            SELECT *
            FROM dbo.dba_missingIndexStoredProc
            WHERE executionDate >= @currentDateTime;
        END;
 
        /* If you have an open transaction, commit it */
        IF @@TRANCOUNT > 0
            COMMIT TRANSACTION;
 
    END Try
    BEGIN Catch
 
        /* Whoops, there was an error... rollback! */
        IF @@TRANCOUNT > 0
            ROLLBACK TRANSACTION;
 
        /* Return an error message and log it */
        EXECUTE dbo.dba_logError_sp;
 
    END Catch;
 
    /* Clean-Up! */
    DROP TABLE #missingIndexes;
 
    SET NOCOUNT OFF;
    RETURN 0;
END
Go

Not know what “EXECUTE dbo.dba_logError_sp;” is doing? Check out my blog post on Error Handling in T-SQL.

HTH!

Michelle

Source: http://sqlfool.com/2009/03/find-missing-indexes/