Monitoring Progress of UPDATE

How to monitor the progress of an UPDATE statement sent to SQL Server? Unfortunately, SQL Server currently doesn’t support an option to monitor the progress of DML operations. In the case of UPDATE against large tables, it might be much faster to recreate the table, e.g. with SELECT … INTO. But suppose that INSERT could take a very long time too and you prefer to update the data instead. Here is how to “monitor” the progress while the UPDATE statement is doing its job.

Suppose you are updating the entire table and it has 138,145,625 rows (consider doing the update in batches to avoid running out of log space). Let’s say the UPDATE statement changes the RowStartColumn column to the first day of the month:

UPDATE bi.FactAccountSnapshot

SET RowStartDate = DATEADD(MONTH, DATEDIFF(MONTH, 0, RowStartDate), 0);

Use these statements to monitor the remaining work by using a reverse WHERE clause. Make sure to execute both statements (SET TRAN and SELECT together) so that the SELECT statement can read the uncommitted changes.

SET TRAN ISOLATION LEVEL READ UNCOMMITTED;

SELECT CAST(1 – CAST(COUNT(*) AS DECIMAL) / 138145625 AS DECIMAL(5, 2)) AS PercentComplete ,COUNT(*) AS RowsRemaining

FROM bi.FactAccountSnapshot

WHERE RowStartDate <> DATEADD(MONTH, DATEDIFF(MONTH, 0, RowStartDate), 0);

What about INSERT? If you know how many rows you are inserting, you can simply check the current count of the inserted rows by using the sp_spaceused stored procedure:
sp_spaceused ‘tableName’.