problems with full-text search in postgres - postgresql

Question

I have the next table, and data:
/* script for people table, with field tsvector and gin */
CREATE TABLE public.people (
id INTEGER,
name VARCHAR(30),
lastname VARCHAR(30),
complete TSVECTOR
)
WITH (oids = false);
CREATE INDEX idx_complete ON public.people
USING gin (complete);
/* data for people table */
INSERT INTO public.people ("id", "name", "lastname", "complete")
VALUES
(1, 'MICHAEL', 'BRYANT BRYANT', '''bryant'':2,3 ''michael'':1'),
(2, 'HENRY STEVEN', 'BUSH TIESSEN', '''bush'':3 ''henri'':1 ''steven'':2 ''tiessen'':4'),
(3, 'WILLINGTON STEVEN', 'STEPHENS FLINN', '''flinn'':4 ''stephen'':3 ''steven'':2 ''willington'':1'),
(4, 'BRET', 'MARTINEZ AROCH', '''aroch'':3 ''bret'':1 ''martinez'':2'),
(5, 'TERENCE BERT', 'CAVALIERE ENRON', '''bert'':2 ''cavalier'':3 ''terenc'':1');
I need retrieve the names and lastnames, according the tsvector field. Actually I have the query:
SELECT * FROM people WHERE complete ## to_tsquery('WILLINGTON & FLINN');
And the result is right (the third record). BUT if I try with
SELECT * FROM people WHERE complete ## to_tsquery('STEVEN & FLINN');
/* the same record! */
I don't have results. Why? What can I do?

Answer 1

You should use the same language to search your table as the values in your field 'complete' where inserted.
Check the result of that query compared english and german:
select * ,
to_tsvector('english', concat_ws(' ', name, lastname )) as english,
to_tsvector('german', concat_ws(' ', name, lastname )) as german
from public.people
so that should work for you :
SELECT * FROM people WHERE complete ## to_tsquery('english','STEVEN & FLINN');

Answer 2

You are probably using a text search configuration where either STEVEN or FLINN are modified by stemming.
I can reproduce this here:
test=> SHOW default_text_search_config;
default_text_search_config
----------------------------
pg_catalog.german
(1 row)
test=> SELECT complete FROM public.people WHERE id = 3;
complete
-------------------------------------------------
'flinn':4 'stephen':3 'steven':2 'willington':1
(1 row)
test=> SELECT * FROM ts_debug('STEVEN & FLINN');
alias | description | token | dictionaries | dictionary | lexemes
-----------+-----------------+--------+---------------+-------------+---------
asciiword | Word, all ASCII | STEVEN | {german_stem} | german_stem | {stev}
blank | Space symbols | | {} | |
blank | Space symbols | & | {} | |
asciiword | Word, all ASCII | FLINN | {german_stem} | german_stem | {flinn}
(4 rows)
test=> SELECT * FROM public.people
WHERE complete ## to_tsquery('STEVEN & FLINN');
id | name | lastname | complete
----+------+----------+----------
(0 rows)
So you see, the German Snowball dictionary stems STEVEN to stev.
Since complete contains the unstemmed version steven, no match is found.
You should use the same text search configuration when you populate complete and in the query.