fenLisesi,
I didn't post yet because I wanted to make sure hv agreed that it could work (he hasn't yet). The algorithm may not be the most efficient but it should be something like 2N where N represents the number of columns

Treat each column as a bitstring. Walk each column and push the column index into a hash key (the bitstring itself). At the end, walk the hash looking for hash keys with a value count that is the same as the number of bits in the key. Since the value is an array of the column indices, you know what columns to extract.

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