How to make columns more weighty in PostreSQL when searching?

Question

PostgreSQL

In Elasticsearch I can do like this

GET /_search
{
  "query": {
    "multi_match" : {
      "query" : "this is a test",
      "fields" : [ "subject^3", "message" ] 
    }
  }
}

We are looking for "this is a test" in 2 fields/columns: subject, message. The subject field is three times more powerful than the message field.
How to achieve the same with PostgreSQL?

Answer 1

You, I hope, about FTS in PostgreSQL? Then, most likely, the answer is contained here https://www.postgresql.org/docs/9.5/static/textsea...
Creating an index

UPDATE  table SET ftsindex = 
setweight(to_tsvector(coalesce(subject,'')), 'A') ||
setweight(to_tsvector(coalesce(message,'')), 'D');

When creating an index, you can assign a conditional weight to different fields, from A to D.
When querying, you can specify a real weight for the conditional weight .

SELECT id, ts_rank_cd({1.0, 1.0, 1.0, 3.0}, ftsindex, query) AS rank
FROM table, to_tsquery('this is a test') query
WHERE query @@ ftsindex
ORDER BY rank DESC
LIMIT 10;

Answer 2

SELECT * FROM
(SELECT id, 3 AS rank FROM mail WHERE subject like '%query%'
UNION ALL
SELECT id, 1 AS rank FROM mail WHERE message like '%query%') AS t
ORDER BY rank DESC