You don't give enough details, but if your worry is whether you can store one k-line in your hash, then don't worry, this is really no problem (unless your lines are several hundreds of kB long, of course). Even storing a million 100-bytes lines is usually not a problem on most systems, but that's getting closer to the limit; above that, the outcome will depend on your system's memory and other characteristics, the average line length and other similar factors.