SQL Server: Why a Session With sp_readrequest Takes so Long to Execute

While applying, Long Running Sessions Detection Job on a production server, we start receiving alert that a session is taking more then 3 minutes. But what actually this session was doing. Here is the alert report.

SP ID	Stored Procedure Call	DB Name	Executing Since
58	msdb.dbo.sp_readrequest;1�	msdb	3 min

sp_readrequest is a system stored procedure, which basically reads a message request from the the queue and returns its  contents.

This process can remain active for a time we have configured for parameter DatabaseMailExeMinimumLifeTime, at the time of database mail profile configuration. 600 seconds is the default value for this external mail process. According to BOL DatabaseMailExeMinimumLifeTime is the The minimum amount of time, in seconds, that the external mail process remains active.

This can be changed, at the time of mail profile configuration or you can just use update query to change this time.

UPDATE msdb.dbo.sysmail_configuration

SET paramvalue = 60 --60 Seconds

WHERE paramname = 'DatabaseMailExeMinimumLifeTime'

We have changed this to 60 seconds to resolve our problem.

SQL Server Errors: ORDER BY items must appear in the select list if SELECT DISTINCT is specified

SQL Server force you to put columns in SELECT DISTINCT list which are part of ORDER BY clause. But what if we don’t want to add that column/s in SELECT list. Lets try it.

--create temporary table to hold records

CREATE TABLE #DistinctSortTest (Val1 INT, Val2 INT)

GO

--insert some records

INSERT INTO #DistinctSortTest

VALUES (1,100),(8,55),(3,33),(1,1),(9,999)

GO

--lets see what we have in table

SELECT * FROM #DistinctSortTest

GO

 
From this table we need only “Val1” column with distinct values BUT sorting output with “Val2”. Lets try simple query.

SELECT DISTINCT Val1

FROM #DistinctSortTest

ORDER BY Val2

Opps. Error

Msg 145, Level 15, State 1, Line 1

ORDER BY items must appear in the select list if SELECT DISTINCT is specified.

To resolve this problem, we can use GROUP BY clause with MIN()or MAX() function in ORDER BY clause. 

SELECT  Val1

FROM #DistinctSortTest

GROUP BY Val1

ORDER BY MIN(Val2)

Through GROUP BY (all select columns) we will achive functionality of DISTINCT and MIN()/MAX() functions for sorting. MIN() in Order By clause can be used for ASC sort and MAX() for DESC sort.

--drop temporary table when not required

DROP TABLE #DistinctSortTest

SQL Server: Script to Generate HTML Report/mail for Databses Current Size, Growth Rate and Available Disk Space

Working with multiple databases on multiple instances is a tough job. You need to monitor all these instances for everything. Best way to keep eye on every instance activity is SQL Server Jobs.

How quickly databases on these instances are growing and does target instance has required space on hard drives ? These are basic questions which every DBA keeps in mind during instance monitoring.

Amna Asif has suggested a better script to create a proper report (to mail) for actual database space, required and currently available on hard drives.

Download Script
 /*

 Script to send an alert through mail, with information that how many drive
 space is required from next databases growth on a specific instance and how many
 space is available.

 Script By: Amna Asif for ConnectSQL.blogspot.com

 */


 DECLARE @dbName varchar(200),
    @Qry Nvarchar(max)
 DECLARE @dbsize VARCHAR(50),
    @logsize VARCHAR(50),
    @reservedpages VARCHAR(50),
    @usedpages VARCHAR(50),
    @pages VARCHAR(50)

 SET @dbName = ''

---Get LOG File Spaces of All Databases--
 CREATE TABLE #LogSpaceStats
    (
      RowID INT IDENTITY
                PRIMARY KEY,
      dbName SYSNAME,
      Totallogspace DEC(20, 2),
      UsedLogSpace DEC(20, 2),
      Status CHAR(1)
    )
   
 INSERT #LogSpaceStats
        ( dbName, Totallogspace, UsedLogSpace, Status )
        EXEC ( 'DBCC sqlperf(logspace) WITH NO_INFOMSGS'
            )
    
--Get Info of All Drives
 DECLARE @ServerDrives TABLE
    (
      RowID int IDENTITY
                PRIMARY KEY,
      Drive char,
      DriveSpace varchar(100),
      Required_Space varchar(100)
    )
 INSERT INTO @ServerDrives
        ( Drive, DriveSpace )
        EXEC master.sys.xp_fixeddrives
--Temporary Table to hold requried data
 CREATE TABLE #ServerFileStats
    (
      RowID INT IDENTITY
                PRIMARY KEY,
      dbName SYSNAME,
      Database_DSize varchar(100),
      Allocated_Space varchar(100),
      Unallocated_Space varchar(100),
      Unused varchar(100),
      Database_LSize varchar(100),
      UsedLogSpace DEC(20, 2),
      FreeLogSpace DEC(20, 2),
      FDataFileGrowth DEC(20, 2),
      FLogFileGrowth DEC(20, 2),
      DataFileDrive char,
      LogFileDrive char
    )
  
--Cursor Used to get each database size on given instance
 DECLARE cur_dbName CURSOR
    FOR SELECT  NAME
        FROM    SYS.DATABASES
        WHERE   state_desc = 'ONLINE'
                AND is_read_only = 0
 OPEN cur_dbName
 FETCH NEXT FROM cur_dbName into @dbName
 WHILE @@FETCH_Status = 0
    BEGIN
        SELECT  @Qry = ' SELECT @dbsizeOUT = sum(convert(bigint,
                              case when status & 64 = 0 then size
                              else 0 end))
                              ,@logsizeOUT = sum(convert(bigint,
                                    case when status & 64 <> 0 then size
                                    else 0 end)) 
                                       FROM [' + @dbName + '].dbo.sysfiles '
                             
        EXEC sp_executesql @Qry,
            N'@dbsizeOUT  nvarchar(50) OUTPUT,@logsizeOUT  nvarchar(50) OUTPUT',
            @dbsizeOUT = @dbsize OUTPUT, @logsizeOUT = @logsize OUTPUT ; 

        SELECT  @Qry = ' SELECT @reservedpagesOUT = sum(a.total_pages)

                                 ,@usedpagesOUT = sum(a.used_pages)
                      FROM [' + @dbName + '].sys.partitions p join [' + @dbName
                + '].sys.allocation_units a on p.partition_id = a.container_id 
                      LEFT JOIN [' + @dbName
                + '].sys.internal_tables it on p.object_id = it.object_id'

        EXEC sp_executesql @Qry,

     N'@reservedpagesOUT  nvarchar(50) OUTPUT,@usedpagesOUT nvarchar(50) OUTPUT',
            @reservedpagesOUT = @reservedpages OUTPUT,
            @usedpagesOUT = @usedpages OUTPUT ; 
       
        SELECT  @Qry = ' INSERT INTO #ServerFileStats                
                         SELECT DB_size.Database_Name
                         , DB_size.Database_DSize
                         , DB_size.Allocated_Space
                         , DB_size.Unallocated_Space
                         , DB_size.Unused
                         , DB_size.Database_LSize
             , (lss.TotalLogSpace*(lss.UsedLogSpace/100)) UsedLogSpace
             , (TotalLogSpace-(TotalLogSpace*(UsedLogSpace/100))) FreeLogSpace
             ,CASE mfD.is_percent_growth
              WHEN 0 THEN CONVERT(DEC(15,2),(mfD.growth* 8192 / 1048576))
              ELSE CONVERT(DEC(15,2),(CONVERT(DEC(15,2),REPLACE(DB_size.Database_DSize,'' MB'',''''))
                              *mfD.growth/100)) END  FDataFileGrowth
                          ,
                          CASE mfL.is_percent_growth WHEN 0 THEN CONVERT(DEC(15,2),(mfL.growth* 8192 / 1048576))
                          ELSE CONVERT(DEC(15,2),(CONVERT(DEC(15,2),REPLACE(DB_size.Database_DSize,'' MB'',''''))
                          *mfL.growth/100)) END  FLogFileGrowth
                         ,LEFT(mfD.physical_name,1) DataFileDrive
                         ,LEFT(mfL.physical_name,1) LogFileDrive
                         FROM
                         (
                          SELECT Database_Name = ''' + @dbName
                + '''
, Database_DSize = ltrim(str((convert (dec (15,2),'
       + @dbsize
       + '))* 8192 / 1048576,15,2) + '' MB'')
, ''Allocated_Space''=ltrim(str((CASE WHEN '
       + @dbsize + ' >= ' + @reservedpages
       + '
THEN convert (DEC (15,2),'
                + @reservedpages
                + ')* 8192 / 1048576
ELSE 0 end),15,2) + '' MB'') 
                                    , ''Unallocated_Space'' = ltrim(str((CASE WHEN '
               + @dbsize + ' >= ' + @reservedpages
                + '
THEN  (convert (DEC (15,2),'
                + @dbsize + ') - convert (DEC (15,2),' + @reservedpages
                + '))* 8192 / 1048576
ELSE 0 end),15,2) + '' MB'')
                                    , ''Unused'' =ltrim(str((CAST(('
                + @reservedpages + ' - ' + @usedpages
                + ')AS BIGINT) * 8192 / 1024.)/1024,15,2) + '' MB'') 
                , Database_LSize = ltrim(str((convert (dec (15,2),'
                + @logsize
                + '))* 8192 / 1048576,15,2) + '' MB'')
  )DB_size LEFT JOIN #LogSpaceStats AS lss on lss.dbName=DB_size.Database_Name
                          INNER JOIN ' + @dbName
                + '.sys.databases db ON DB.name=DB_size.Database_Name
                          INNER JOIN ' + @dbName
                + '.sys.master_files mfD on mfD.database_id=DB.database_id AND mfD.type_desc=''ROWS''
                          INNER JOIN ' + @dbName
                + '.sys.master_files mfL on mfL.database_id=DB.database_id AND mfL.type_desc=''LOG'''

        EXEC ( @Qry

            )

  FETCH NEXT FROM cur_dbName into @dbName
    END
 CLOSE cur_dbName
 DEALLOCATE cur_dbName

 UPDATE @ServerDrives

 SET    Required_Space = SumDriveS.sumofdrivespcae
 FROM   ( SELECT    SUM(CONVERT(DEC(20, 2), sumofdrivespcae)) sumofdrivespcae,
                    DRIVE AS DRIVE
          FROM      ( SELECT    SUM(CONVERT(DEC(20, 2), REPLACE(fss.FDataFileGrowth, ' MB', '')))
                                                sumofdrivespcae,
                                fss.DataFileDrive AS DRIVE
                      FROM      #ServerFileStats fss
                      GROUP BY  fss.DataFileDrive
                      UNION
                      SELECT    SUM(CONVERT(DEC(20, 2), REPLACE(fss.FLogFileGrowth, ' MB', '')))
                                                sumofdrivespcae,
                                fss.LogFileDrive AS DRIVE
                      FROM      #ServerFileStats fss
                      GROUP BY  fss.LogFileDrive ) SumDrive
          GROUP BY  SumDrive.DRIVE ) SumDriveS
        LEFT OUTER JOIN @ServerDrives sd on SumDriveS.Drive = sd.Drive


------------------------------------------------------------------------------
-----------------------------------------Report Mailing-----------------------
DECLARE @Loop int
 DECLARE @Subject varchar(100)
 DECLARE @strMsg varchar(4000)

 SELECT @Subject = 'SQL Monitor Alert: ' + @@SERVERNAME + '        '

        + Convert(varchar, GETDATE())
  Declare @Body varchar(max),
    @TableHead varchar(1000),
    @TableTail varchar(1000),
    @TableHead2 varchar(1000),
    @Body2 varchar(3000)
 Set NoCount On ;
-- Create HTML mail body
 Set @TableTail = '</table></body></html>' ;
  Set @TableHead = '<html><head>' + '<style>'
    + 'td {border: solid black 1px;padding-left:3px;padding-right:3px;padding-top:2px;padding-bottom:2px;font-size:10pt;} '
    + '</style>' + '</head>'
    + '<body><table cellpadding=0 cellspacing=0 border=0>'
    + '<tr><td align=center bgcolor=#E6E6FA><b>Row ID</b></td>'
    + '<td align=center bgcolor=#E6E6FA><b>Database Name</b></td>'
    + '<td align=center bgcolor=#E6E6FA><b>File Group</b></td>'
    + '<td align=center bgcolor=#5F9EA0><b>DF Total Space</b></td>'
    + '<td align=center bgcolor=#5F9EA0><b>DF Allocated Space</b></td>'
    + '<td align=center bgcolor=#5F9EA0><b>DF Unallocated Space</b></td>'
    + '<td align=center bgcolor=#E6E6FA><b>DF Unused</b></td>'
    + '<td align=center bgcolor=#5F9EA0><b>LF Total Space</b></td>'
    + '<td align=center bgcolor=#5F9EA0><b>LF Used Space</b></td>'
    + '<td align=center bgcolor=#5F9EA0><b>LF Unused Space</b></td>'
    + '<td align=center bgcolor=#E6E6FA><b>DF FileGrowth</b></td>'
    + '<td align=center bgcolor=#E6E6FA><b>LF FileGrowth</b></td>'
    + '<td align=center bgcolor=#E6E6FA><b>DF Drive</b></td>'
    + '<td align=center bgcolor=#E6E6FA><b> LF Drive </b></td></tr>' ;

  Select @Body = ( SELECT    td = CONVERT(VARCHAR, ROW_NUMBER() OVER ( ORDER BY dbName ))

                            + CHAR(10),
                            td = ISNULL(dbName, 'Unknown') + CHAR(10),
                            td = ISNULL('Data/LOG', 'Unknown') + CHAR(10),
                            td = ISNULL(Database_DSize, '0.00') + CHAR(10),
                            td = ISNULL(Allocated_Space, '0.00') + CHAR(10),
                            td = ISNULL(Unallocated_Space, '0.00') + CHAR(10),
                            td = ISNULL(Unused, '0.00') + CHAR(10), '',
                            td = ISNULL(Database_LSize, '0.00') + CHAR(10),
                            td = ISNULL(convert(varchar, UsedLogSpace), '0.00')
                            + ' MB' + CHAR(10),
                            td = ISNULL(convert(varchar, FreeLogSpace), '0.00')
                            + ' MB' + CHAR(10),
                            td = ISNULL(convert(varchar, FDataFileGrowth),
                                        '0.00') + ' MB' + CHAR(10), '',
                            td = ISNULL(convert(varchar, FLogFileGrowth),
                                        '0.00') + ' MB' + CHAR(10), '',
                            td = ISNULL(DataFileDrive, '0') + CHAR(10), '',
                            td = ISNULL(LogFileDrive, '0') + CHAR(10), ''
                  FROM      #ServerFileStats
                  ORDER BY  dbName
        FOR       XML RAW('tr'),
                      ELEMENTS )


-- Replace the entity codes and row numbers
 Set @Body = Replace(@Body, '_x0020_', space(1))
 Set @Body = Replace(@Body, '_x003D_', '=')
 Set @Body = Replace(@Body, '<tr><TRRow>1</TRRow>', '<tr bgcolor=#C6CFFF>')
 Set @Body = Replace(@Body, '<TRRow>0</TRRow>', '')

 DECLARE @flag BIT

 SELECT @flag = 1
 FROM   @ServerDrives
 WHERE  convert(dec(15, 2), DriveSpace) < convert(dec(15, 2), Required_Space)
        * 2
 SET @flag = ISNULL(@flag, 0)

 SET @TableHead2 = '<html><head>' + '<style>'

    + 'td {border: solid black 1px;padding-left:1px;padding-right:1px;padding-top:1px;padding-bottom:1px;font-size:8pt;} '
    + '</style>' + '</head>'
    + '<body><table cellpadding=0 cellspacing=0 border=0>'
    + '<tr><td align=center bgcolor=#E6E6FA><b>Row ID</b></td>'
    + '<td align=center bgcolor=#E6E6FA><b>Drive</b></td>'
    + '<td align=center bgcolor=#E6E6FA><b>Drive Space</b></td> '


 IF ( @flag = 0 )
    set @TableHead2 = @TableHead2
     + '<td align=center bgcolor=#E6E6FA><b>Required Drive Space</b></td></tr>' ;
 ELSE
    set @TableHead2 = @TableHead2
     + '<td align=center bgcolor=#FF7F50><b>Required Drive Space</b></td></tr>' ;
         
 Select @Body2 = ( SELECT   td = ROW_NUMBER() OVER ( ORDER BY Drive ),
                            td = ISNULL(Drive, 'Unknown') + char(10),
                            td = ISNULL(DriveSpace + ' MB', 0) + char(10),
                            td = ISNULL(Required_Space + ' MB', 0)
                   FROM     @ServerDrives sd
        For        XML RAW('tr'),
                       Elements )

 Select @Body = @TableHead2 + @Body2 + @TableTail + '<br/><br/><br/><br/>'

        + @TableHead + @Body + @TableTail
-- Send mail
 EXEC msdb.dbo.sp_send_dbmail
      @recipients = 'abc@xyz.com',
    @subject = @Subject,
    @profile_name = 'MyMailProfileName',
    @body = @Body,
    @body_format = 'HTML' ;


 --Drop Temporary Tables When Not Required
 DROP TABLE #ServerFileStats
 DROP TABLE #LogSpaceStats

DF = Data Files
LF = LogFiles