Looping through a large table to batch insert [MSSQL]

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1

The problem I’m having

exploring dbt and have a question. We’re on sql-server and we have some code that bathes loading into the destination table.

staging table may have 30 million records (or more). We don’t want to merge this into final table with one insert (for a few diff reasons) so we batch the insert in increments of 1 million.
See example below - other procs are merging, insert and update.

DECLARE @EndID INT = (SELECT MAX(RowID) FROM stagetable);
DECLARE @CurrentEndID INT


WHILE @StartID <= @EndID
BEGIN

       SET @CurrentEndID = @StartID + @BatchSize -1

               insert into destTable (<cols>)
		SELECT 
                           <cols>
		FROM stagetable a
		WHERE RowID >= @StartID 
			AND RowID <= @CurrentEndID
                       and  not exists (select * from desttable  t where t.key  = a.key)

SET @StartID += @BatchSize
end