This is in a fairly common family of issues. I'd suggest you review some of the answers to previous posts in the vein (for example Pattern matching across two files, Need something better than grep -f!). I'd also say nested loops are a horrible solution here, and you should swap to a hash or, if the files are too large for that, a database. We might be able to offer some more concrete advice if you show us exactly what you are doing, e.g. post code.

#11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

In reply to Re: Compare two Large FlatFiles by kennethk
in thread Compare two Large FlatFiles by suneel.reddy

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