Hello, @m-p, @peterjones, @alan-kilborn, @troshindv and All,
Oh…! Indeed, dealing with two files of 7,400,000 and 1,200,000 lines is not an easy task ! So you will have to work with a 8,600,000 lines file : good luck !
Do not hesitate to ask me for more information if you encounter difficulties in implementing my method !
First, I would advice you to repeat my own tiny example, first, to get its general idea
Regarding your real example, I would say that :
The N++ sort feature is very quick, in all cases
I suppose that the numbering operation, with the column editor, should not be very long, too !
May be, the first of the three regex S/R will probably take some time. Just be patient : it should work in the end !
Best Regards
guy038