Function length

Returns the number of lexemes or word stems in a text search vector.

length(tsv TSVECTOR) RETURNS INT4

SELECT line_number, ts_vec, length(ts_vec) 
FROM ts_readme 
ORDER BY line_number 
LIMIT 3;
 
 line_number |                               ts_vec                                | length
-------------+---------------------------------------------------------------------+--------
           1 | 'full':2 'text':3 'extens':5 'search':4 'tsearch2':1 'postgresql':7 |      6
           2 |                                                                     |      0
           3 | '10':1 'avail':8 'onlin':2 'version':3 'document':6                 |      5
(3 rows)