Suggestions on How to Improve Delete

• RGP

  SSCarpal Tunnel

  Points: 4381

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  December 27, 2018 at 4:13 pm

  #373371

  Hi Guys, 
  Any suggestions on how to improve this Delete?
  delete was causing tempdb log to grow, also would UPDATE be faster than Delete , there are around 31 million records to delete...thanks

  DECLARE  @return_value int
  EXEC  @return_value = [dbo].[sp_Batches]
     @TARGET_JOB_DEFID =78,
     @TARGET_JOB_STATUS = -7,
     @TARGET_DELETE_BATCHSIZE = 100000,
     @TARGET_DELETE_BATCHES = 10

• Lynn Pettis

  SSC Guru

  Points: 442467

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  December 27, 2018 at 4:20 pm

  #2017470

  rinu philip - Thursday, December 27, 2018 4:13 PM

  Hi Guys, 
  Any suggestions on how to improve this Delete?
  delete was causing tempdb log to grow, also would UPDATE be faster than Delete , there are around 31 million records to delete...thanks

  DECLARE  @return_value int
  EXEC  @return_value = [dbo].[sp_Batches]
     @TARGET_JOB_DEFID =78,
     @TARGET_JOB_STATUS = -7,
     @TARGET_DELETE_BATCHSIZE = 100000,
     @TARGET_DELETE_BATCHES = 10

  Without the code for the stored procedure how are we supposed to know if it can be improved?

• RGP

  SSCarpal Tunnel

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  December 27, 2018 at 4:33 pm

  #2017471

  Thanks for the quick response, I’ll post the code soon

• Jeff Moden

  SSC Guru

  Points: 1003851

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  December 27, 2018 at 4:50 pm

  #2017472

  RGP - Thursday, December 27, 2018 4:33 PM

  Thanks for the quick response, I’ll post the code soon

  Also post how many "records" there are total in the table, please.

  --Jeff Moden

  ---

  RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
  First step towards the paradigm shift of writing Set Based code:
  ________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

  Change is inevitable... Change for the better is not.
  

  ---

  Helpful Links:
  How to post code problems
  How to Post Performance Problems
  Create a Tally Function (fnTally)
  

• RGP

  SSCarpal Tunnel

  Points: 4381

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  December 28, 2018 at 6:44 am

  #2017495

  Lynn Pettis - Thursday, December 27, 2018 4:20 PM

  rinu philip - Thursday, December 27, 2018 4:13 PM

  Hi Guys, 
  Any suggestions on how to improve this Delete?
  delete was causing tempdb log to grow, also would UPDATE be faster than Delete , there are around 31 million records to delete...thanks

  DECLARE  @return_value int
  EXEC  @return_value = [dbo].[sp_Batches]
     @TARGET_JOB_DEFID =78,
     @TARGET_JOB_STATUS = -7,
     @TARGET_DELETE_BATCHSIZE = 100000,
     @TARGET_DELETE_BATCHES = 10

  Without the code for the stored procedure how are we supposed to know if it can be improved?

  Please see the attached SP

• RGP

  SSCarpal Tunnel

  Points: 4381

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  December 28, 2018 at 6:45 am

  #2017496

  Jeff Moden - Thursday, December 27, 2018 4:49 PM

  RGP - Thursday, December 27, 2018 4:33 PM

  Thanks for the quick response, I’ll post the code soon

  Also post how many "records" there are total in the table, please.

  The table has around 30 million records

• Thom A

  SSC Guru

  Points: 99126

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  December 28, 2018 at 7:00 am

  #2017497

  For those that don't want to download the file (formatting courtesy of SSC paste interpreter):
  SET ANSI_NULLS ON
GO

  SET QUOTED_IDENTIFIER ON
GO

  CREATE PROCEDURE [dbo].[sp_Batches]
  @TARGET_JOB_DEFID INT,
  @TARGET_JOB_STATUS INT,
  @TARGET_DELETE_BATCHSIZE INT = 10000,
  @TARGET_DELETE_BATCHES INT = 100
AS
BEGIN
  DECLARE @NUM_JOBS_TO_DELETE INT;
  SET @NUM_JOBS_TO_DELETE = @TARGET_DELETE_BATCHSIZE * @TARGET_DELETE_BATCHES;

    SELECT TOP (@NUM_JOBS_TO_DELETE) j.[JOB_ID],
    ROW_NUMBER() OVER (ORDER BY [JOB_ID]) / @TARGET_DELETE_BATCHSIZE AS [BATCH_NUM]
   INTO [#TMP_JOB_TO_DELETE]
    FROM [dbo].[JOB] j WITH(READPAST)
      WHERE j.[JOB_DEFINITION_ID] = @TARGET_JOB_DEFID AND j.[JOB_STATUS] = @TARGET_JOB_STATUS;

    IF (@@ERROR <> 0)
  BEGIN
   GOTO Failed;
  END

    CREATE CLUSTERED INDEX [IX_TMP_JOB_TO_DELETE] ON [#TMP_JOB_TO_DELETE]([BATCH_NUM]);
  IF (@@ERROR <> 0)
  BEGIN
   GOTO Failed;
  END

    CREATE TABLE [#TMP_JOB_DELETE_ID]([JOB_ID] bigint);

    IF ((SELECT COUNT(*) FROM [#TMP_JOB_TO_DELETE]) > 0)
  BEGIN
   DECLARE @DELETED_JOB_COUNT int;
   SET @DELETED_JOB_COUNT = 0;

     DECLARE @BATCH_NUMBER int;
   SET @BATCH_NUMBER = 0;

     DECLARE @CURRENT_BATCH_SIZE int;

     WHILE (1 = 1)
   BEGIN
     TRUNCATE TABLE [#TMP_JOB_DELETE_ID];

      INSERT INTO [#TMP_JOB_DELETE_ID]([JOB_ID])
    SELECT [JOB_ID]
      FROM [#TMP_JOB_TO_DELETE]
       WHERE BATCH_NUM = @BATCH_NUMBER;

      IF (@@ERROR <> 0)
    BEGIN
      GOTO Failed;
    END

          SET @CURRENT_BATCH_SIZE = (SELECT COUNT(*) FROM [#TMP_JOB_DELETE_ID]);
    IF (@CURRENT_BATCH_SIZE = 0)
    BEGIN
      BREAK;
    END

     
            BEGIN TRANSACTION;
    DELETE FROM [dbo].[JOB]
       WHERE [JOB_ID] IN (SELECT [JOB_ID] FROM [#TMP_JOB_DELETE_ID]);

              COMMIT TRANSACTION;
            IF (@@ERROR <> 0)
    BEGIN
      GOTO Failed;
    END
    
    SET @DELETED_JOB_COUNT = @DELETED_JOB_COUNT + @CURRENT_BATCH_SIZE;

     
    SET @BATCH_NUMBER = @BATCH_NUMBER + 1;
   END

     SELECT @DELETED_JOB_COUNT;
   DROP TABLE [#TMP_JOB_TO_DELETE];
   DROP TABLE [#TMP_JOB_DELETE_ID];
  
   RETURN;
  END

  Failed:
  SELECT 0;
END
GO


  Thom~

  Excuse my typos and sometimes awful grammar. My fingers work faster than my brain does.
  Larnu.uk

• Jeff Moden

  SSC Guru

  Points: 1003851

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  December 28, 2018 at 7:17 am

  #2017499

  RGP - Friday, December 28, 2018 6:45 AM

  Jeff Moden - Thursday, December 27, 2018 4:49 PM

  RGP - Thursday, December 27, 2018 4:33 PM

  Thanks for the quick response, I’ll post the code soon

  Also post how many "records" there are total in the table, please.

  The table has around 30 million records

  OK.  I'm a little confused by that.  The table has around 30 million records but, according to your original post, you want to delete 31 million records??? :blink:

  Let me ask a different way...
  1.  How many row currently exist in the table?
  2.  Now many rows do you want to delete from the table?

  --Jeff Moden

  ---

  RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
  First step towards the paradigm shift of writing Set Based code:
  ________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

  Change is inevitable... Change for the better is not.
  

  ---

  Helpful Links:
  How to post code problems
  How to Post Performance Problems
  Create a Tally Function (fnTally)
  

• RGP

  SSCarpal Tunnel

  Points: 4381

  More actions

  December 28, 2018 at 8:49 am

  #2017517

  Jeff Moden - Friday, December 28, 2018 7:17 AM

  RGP - Friday, December 28, 2018 6:45 AM

  Jeff Moden - Thursday, December 27, 2018 4:49 PM

  RGP - Thursday, December 27, 2018 4:33 PM

  Thanks for the quick response, I’ll post the code soon

  Also post how many "records" there are total in the table, please.

  The table has around 30 million records

  OK.  I'm a little confused by that.  The table has around 30 million records but, according to your original post, you want to delete 31 million records??? :blink:

  Let me ask a different way...
  1.  How many row currently exist in the table?
  2.  Now many rows do you want to delete from the table?

  1.  How many row currently exist in the table? => 63 million 
  2.  Now many rows do you want to delete from the table? ==> 31 million

• Scott Coleman

  One Orange Chip

  Points: 27452

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  December 28, 2018 at 2:57 pm

  #2017558

  Why not simply delete batches until there are no more left?  I don't see why the temp tables and transaction are necessary, the procedure just exits if an error occurs.

  WHILE 1=1 BEGIN
  DELETE TOP (@TARGET_DELETE_BATCHSIZE)
  FROM dbo.JOB
  WHERE JOB_DEFINITION_ID = @TARGET_JOB_DEFID AND JOB_STATUS = @TARGET_JOB_STATUS;

    IF @@ROWCOUNT = 0   BREAK;
END

• Jeff Moden

  SSC Guru

  Points: 1003851

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  December 28, 2018 at 3:32 pm

  #2017564

  RGP - Friday, December 28, 2018 8:49 AM

  Jeff Moden - Friday, December 28, 2018 7:17 AM

  RGP - Friday, December 28, 2018 6:45 AM

  Jeff Moden - Thursday, December 27, 2018 4:49 PM

  RGP - Thursday, December 27, 2018 4:33 PM

  Thanks for the quick response, I’ll post the code soon

  Also post how many "records" there are total in the table, please.

  The table has around 30 million records

  OK.  I'm a little confused by that.  The table has around 30 million records but, according to your original post, you want to delete 31 million records??? :blink:

  Let me ask a different way...
  1.  How many row currently exist in the table?
  2.  Now many rows do you want to delete from the table?

  1.  How many row currently exist in the table? => 63 million 
  2.  Now many rows do you want to delete from the table? ==> 31 million

  It would likely be much more efficient if you did a minimally logged copy of the rows you want to keep into a new table, drop the original table, and rename the new table the same as the old one.

  Otherwise, just use a script similar to what Scott Coleman used above.  There's just one little change to prevent a final massive expensive scan at the end of the run....  change the WHERE clause to look for rowcounts less than the batch size.  Like this...
  
  IF @@ROWCOUNT < @TARGET_DELETE_BATCHSIZE  BREAK;


  --Jeff Moden

  ---

  RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
  First step towards the paradigm shift of writing Set Based code:
  ________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

  Change is inevitable... Change for the better is not.
  

  ---

  Helpful Links:
  How to post code problems
  How to Post Performance Problems
  Create a Tally Function (fnTally)
  

• RGP

  SSCarpal Tunnel

  Points: 4381

  More actions

  December 28, 2018 at 5:59 pm

  #2017574

  Wonderful thanks!!