What strategy for random accession of records in massive FASTA file?

[John Lenton]

> If you could help me figure out how to code a solution
> that won't be a resource whore, I'd be _very_ grateful. (I'd prefer
to
> keep it in Python only, even though I know interaction with a
> relational database would provide the fastest method--the group I'm
> trying to write this for does not have access to a RDBMS.)
You don't need a RDBMS; I'd put it in a DBM or CDB myself.