Function setweight

Marks all elements of a text search vector with the same letter- either 'A', 'B', 'C', or 'D'. This makes it possible to concatenate text search vectors and later assign different weights by letter within the rank function. 'D' is the default weight and is normally not displayed.

setweight(tsv TSVECTOR, letter CHAR) RETURNS TSVECTOR

SELECT setweight(ts_vec, 'A') 
FROM ts_readme 
WHERE line_number = 1;

                                 setweight
---------------------------------------------------------------------------
 'full':2A 'text':3A 'extens':5A 'search':4A 'tsearch2':1A 'postgresql':7A
(1 row)