Without even looking at your code, my first reaction upon hearing about 480 columns, 8,000,000 lines and a 6G file is "put it into a database and let the database worry about that".

Once the data's in a database, you can group similar records together, look at just a subset, and so forth.

Alex / talexb / Toronto

"Groklaw is the open-source mentality applied to legal research" ~ Linus Torvalds

In reply to Re: Huge data file and looping best practices by talexb
in thread Huge data file and looping best practices by carillonator

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