I think he meant "external" to Perl ...

A lot of the initial discussion was certainly predicated on assumptions; there was not a lot of detail in the request.

For example, I assumed we were talking about half a million or less records, each with a primary key and possibly a secondary key. Given my assumptions, it's not too painful to use a Hash of Hashes. For exact queries, the hash is a Big Win. For a partial query, doing a foreach through the hash isn't that painful.

As soon as the OP mentioned he was talking gigabytes of data, I withdrew my original suggestion.

So DBI+DBD::SQLite does fit the bill.

I agree completely.