When faced with a similar situation, I'd build all the data structures I'd want concurrently as I was reading my input. That was before I knew how to use a database.

Looking at your situation now, I'd say load any given data set into a database (PostgreSQL, SQLite, MySQL) with DBI and then query it for management's burning questions. If you're not familiar with SQL already, you might not see the advantage of this right away, but databases are already designed to do this kind of work on data too big to fit in memory.

In reply to Re^3: Invert a hash... not a FAQ (I hope) by kyle
in thread Invert a hash... not a FAQ (I hope) by djacobow

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