I understand that file 1 is not sorted and that doesn't matter to me. Lines from file 1 can be read and processed without having to store file 1 values.

File 2 values, however, need to be stored so they can be examined 2.5 million times (once for each line in file 1), so I want to minimize the effort needed to determine if a line in file 1 matches values saved from file 2.

You said above that file 2 is sorted by numeric value on fields 1 and 2 with field 1 being the primary sort key. But, the value marked in red in your example above shows that file 2 is not sorted as you described. It is also strange that that entry has the high end of the range with a value lower than the low end of the range. Did you perhaps intend for the second set of values to be:

Code:

2 1234 9999
2 2500 10000
2 14000 192000

instead of:

Code:

2 1234 9999
2 25000 10000
2 14000 192000

or do we have to reverse the order of values in fields 2 and 3 if field 2's value is greater than field 3's value?