I have problem when mload is processing. I found error in error tables error code 2796; however, data are still loaded to taget table but it is quite slow because of this error.
Could you please suggest me what is the cause of this error?
As the message says, you issued a DELETE for a row that was missing (no row matched the WHERE condition). By default, this is considered an error and is "marked" or logged to the error table. If you don't care, you can specify IGNORE MISSING DELETE ROWS in the DML LABEL.