PostgreSQL – How to Create a Citation from a Text Field

Native full-text can handle all of the features you've mentioned.

• Ranking/relevance, weighting
• Word inflection and expansion
• Customisable noise words and thesaurus

Whether or not it will be the best solution for your particular domain is a tough call. Rather than attempt to hand-roll an alternative, spike a proof of concept using SQL FTS and repeat the exercise with one or more open source alternatives.

Lucene is the obvious contender to compare and comes with the "Stack Overflow search is now 81% less crappy" endorsement of the SO team.

You want to sort by ts_rank() or ts_rank_cd()

By default, those terms would give the same ranks, but you can normalize by length

Try:

select
  *
from geocode.addresses
where
  ...
order by 
  ts_rank( to_tsvector(...), plainto_tsquery(...), 1) desc
limit 1

Where the ts_rank(..., ..., 1) divides the rank by 1 + the logarithm of the document length

There are other ts_rank normalizations in the link