Question

Write a program to delete the content provided by user from the binary file. The file is very large and can't fit in computers memory.

Answer 1

The original file is processed record by record, so the complete file is never loaded into memory.

import os
import pickle

def delete_from_binary(filename, unwanted_value):
    temporary = filename + ".tmp"

    with open(filename, "rb") as source, open(temporary, "wb") as target:
        try:
            while True:
                record = pickle.load(source)
                if record != unwanted_value:
                    pickle.dump(record, target)
        except EOFError:
            pass

    os.replace(temporary, filename)

value = input("Enter content to delete: ")
delete_from_binary("data.dat", value)

If the binary file contains integers or dictionaries, convert the user input to the same type before comparison.