Rest of the described approaches relies on data being in memory rather on disk - not sure whether it was microsd card, SSD over USB, etc. but there's in memory option for SQLite.
Having that in mind it's time to optimize storage - instead of text just store using two 64 bit integers and it was already noticed two indexes are not very helpful - just create one that has both columns included - preferable as primary key so you don't waste space and already have rest of the select data included in single lookup.
Happy to see revisited results, but still not sure if that's a best approach for your problem - but seems like obvious improvements for generic SQL approach.
Rest of the described approaches relies on data being in memory rather on disk - not sure whether it was microsd card, SSD over USB, etc. but there's in memory option for SQLite.
Having that in mind it's time to optimize storage - instead of text just store using two 64 bit integers and it was already noticed two indexes are not very helpful - just create one that has both columns included - preferable as primary key so you don't waste space and already have rest of the select data included in single lookup.
Happy to see revisited results, but still not sure if that's a best approach for your problem - but seems like obvious improvements for generic SQL approach.