herculean and colossal

herculean

adj

1. requiring tremendous effort, strength, etc. a herculean task

2. (sometimes capital) resembling Hercules in strength, courage, etc.

co·los·sal

adj.

Of a size, extent, or degree that elicits awe or taxes belief; immense. Synonyms -enormous.

Moreover, the problem will come in reduplication of the structure. A register of more than 100 million identities sounds a distant dream. It's a herculean task to build such a colossal database.