Sort postings by frequencies then by positions
Sort postings by frequencies then by positions

Sort term index postings first by frequencies and then by positions.
Greater frequencies go before smaller and smaller position values go before greater.
If both are equal, lexicographically smaller posting go first.

pundunlabs/erl_rocksdb,pundunlabs/erl_rocksdb,pundunlabs/erl_rocksdb