Data management processing insert/delete statement

Summary:

We are loading two large files, one file takes significantly more time.

Content (required):

For a customer we are loading actual files per month with a large number of records:

File 1: +/- 680.000 records (170k rows, with 4 amounts as columns)

File 2: +/- 2.600.000 records (650k rows, with 4 amounts as columns)

File 1 takes about 5 minutes to load, where file 2 takes more than 45 min to load.

From the logs I see that data management for the second file uses batch method for the delete and insert statement:

"Executing delete statement using batch method"

I suspect that this batch methods takes significantly more time.