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

In addition to putting this in a batch with a statement to truncate the log, you also might want to try these tricks:

• Add criteria that matches the first column in your clustered index in addition to your other criteria
• Drop any indexes from the table and then put them back after the delete is done if that's possible and won't interfere with anything else going on in the DB, but KEEP the clustered index

For the first point above, for example, if your PK is clustered then find a range which approximately matches the number of rows that you want to delete each batch and use that:

DECLARE @max_id INT, @start_id INT, @end_id INT, @interval INT
SELECT @start_id = MIN(id), @max_id = MAX(id) FROM My_Table
SET @interval = 100000  -- You need to determine the right number here
SET @end_id = @start_id + @interval

WHILE (@start_id <= @max_id)
BEGIN
     DELETE FROM My_Table WHERE id BETWEEN @start_id AND @end_id AND 

     SET @start_id = @end_id + 1
     SET @end_id = @end_id + @interval
END