Sort a file with huge volume of data given memory constraint

Question

Points:

• We process thousands of flat files in a day, concurrently.
• Memory constraint is a major issue.
• We use thread for each file process

Answer 1

If you can move forward/backward in a file (seek), and rewrite parts of the file, then you should use bubble sort.

You will have to scan lines in the file, and only have to have 2 rows in memory at the moment, and then swap them if they are not in the right order. Repeat the process until there are no files to swap.