SQL Batched Delete

Question

I have a table in SQL Server 2005 which has approx 4 billion rows in it. I need to delete approximately 2 billion of these rows. If I try and do it in a single transaction, th

Answer 1

Here is my example:

-- configure script
-- Script limits - transaction per commit (default 10,000)
-- And time to allow script to run (in seconds, default 2 hours)
--
DECLARE @MAX INT
DECLARE @MAXT INT
--
-- These 4 variables are substituted by shell script.
--
SET @MAX = $MAX
SET @MAXT = $MAXT
SET @TABLE = $TABLE
SET @WHERE = $WHERE

-- step 1 - Main loop
DECLARE @continue INT
-- deleted in one transaction
DECLARE @deleted INT
-- deleted total in script
DECLARE @total INT
SET @total = 0
DECLARE @max_id INT, @start_id INT, @end_id INT, @interval INT
SET @interval = @MAX
SELECT @start_id = MIN(id), @max_id = MAX(id) from @TABLE
SET @end_id = @start_id + @interval

-- timing
DECLARE @start DATETIME
DECLARE @now DATETIME
DECLARE @timee INT
SET @start = GETDATE()
-- 
SET @continue = 1
IF OBJECT_ID (N'EntryID', 'U') IS NULL 
BEGIN
    CREATE TABLE EntryID (startid INT)
    INSERT INTO EntryID(startid) VALUES(@start_id)
END
    ELSE
BEGIN
    SELECT @start_id = startid FROM EntryID
END


WHILE (@continue = 1 AND @start_id <= @max_id)
BEGIN

    PRINT 'Start issued:   ' + CONVERT(varchar(19), GETDATE(), 120)
    BEGIN TRANSACTION
        DELETE 
        FROM @TABLE
        WHERE id BETWEEN @start_id AND @end_id AND @WHERE
        SET @deleted = @@ROWCOUNT
    UPDATE EntryID SET EntryID.startid = @end_id + 1
    COMMIT
    PRINT 'Deleted issued: ' + STR(@deleted) + ' records. ' + CONVERT(varchar(19), GETDATE(), 120) 
    SET @total = @total + @deleted
    SET @start_id = @end_id + 1
    SET @end_id = @end_id + @interval
    IF @end_id > @max_id
        SET @end_id = @max_id

    SET @now = GETDATE()
    SET @timee = DATEDIFF (second, @start, @now)
    if @timee > @MAXT
    BEGIN
    PRINT 'Time limit exceeded for the script, exiting'
    SET @continue = 0
    END
--    ELSE
--    BEGIN
--      SELECT @total 'Removed now', @timee 'Total time, seconds'   
--    END
END

SELECT @total 'Removed records', @timee 'Total time sec' , @start_id 'Next id', @max_id 'Max id', @continue 'COMPLETED? '
SELECT * from EntryID next_start_id

GO