Tag Archives: cursor

How to: Poor man’s cursor template for batch processing

John Sterrett blog|twitter asked a question about “How do I loop by rowcount in SSIS? I have a table with 5 million IDs and would like to loop to process 10K at a time. #sqlhelp”

This cannot be done natively in SSIS but you could create a stored procedure that uses the concept known as “poor man’s cursor” to split it in batches.
I included a template of code that I useĀ  to create smaller transactions that do not block normal users accessing the same tables

Let me know what you think.

/***************************************************************************************
 * Name:            Poor mans cursor example for batch processing
 * Author:            Luke Jian - luke(a.t)sqlpositive.com
 * Creation Date:    11/02/11
 * Purpose:            Template for batch processing using Poor man's cursor
 ***************************************************************************************/
    DECLARE @RowStart [INT]
    DECLARE @RowEnd [INT]
    DECLARE @RowToDo [INT]
    DECLARE @RowDone [INT]
    DECLARE @BatchSize [INT]
    BEGIN
    --    Load Users To Enable
    IF ( OBJECT_ID('[TempDB]..[#PoorManCursor]') IS NOT NULL )
    DROP TABLE [#PoorManCursor]
    SELECT --DISTINCT
    [ID] = IDENTITY ( [INT], 1, 1)
    --.. SOME other rows
    INTO    [#PoorManCursor]
    FROM    dbo.BaseTables
    --ORDER BY [Whatever column for batch order]
    --    Add index to temp table
    --    because table may easily exceed 10,000,000 rows
    CREATE UNIQUE CLUSTERED INDEX [UCPoorManCursorID] ON    [#PoorManCursor] ( [ID] )
    --    Set up batching
    SELECT  @RowStart = 1,
    @RowEnd = @BatchSize, --can use 10K
    @RowToDo = MAX([ID]),
    @RowDone = 0
    FROM    [#PoorManCursor]
    PRINT CAST(@RowToDo AS [VARCHAR]) + ' records to be processed.'
    --    Process batch
    WHILE ( @RowStart <= @RowToDo )
    BEGIN
    BEGIN TRANSACTION
    --        Load PoorManCursor_Tracking
    INSERT  INTO [dbo].[SomeTargetTable]
    (
    [col1],
    [col2],
    [col3],
    [col4]
    )
    SELECT  [col1],
    [col2],
    [col3],
    [col4],
    CURRENT_TIMESTAMP
    FROM    #PoorManCursor
    WHERE   [ID] >= @RowStart
    AND [ID] <= @RowEnd
    COMMIT TRANSACTION
    PRINT CAST(@RowCount AS [VARCHAR])
    + ' records completed in this batch'
    SET @RowDone = @RowDone + @RowCount
    SET @RowStart = @RowStart + @BatchSize
    SET @RowEnd = @RowEnd + @BatchSize
    END
    PRINT CAST(@RowDone AS [VARCHAR]) + ' total records processed.'
    IF ( OBJECT_ID('[TempDB]..[#PoorManCursor]') IS NOT NULL )
    DROP TABLE [#PoorManCursor]
    END