But how many serials do you have to delete? You don't need to hold the master file all in a hash or database at once, if the delete-list is small enough to fit into memory. Iterate over the input file one line at a time. Each line, check the delete-hash to see if this is a line that you need to eliminate. If it is, next;, otherwise, print to your new output file. Move on to the next line... lather, rinse, repeat.

If practical, hold the delete list in an in-memory hash. If it's not practical to do so, hold the delete list in a database. But leave the master list in a flat file.


Dave

In reply to Re^4: 15 billion row text file and row deletes - Best Practice? by davido
in thread 15 billion row text file and row deletes - Best Practice? by awohld

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