Thread: Full text search bug ('russian' regconfig)

Hello!

Text search doesn't work correct with the EQUAL string in text and query (russian dictionary config),
as you can see in example ts_vector receives different from ts_query lexemes for identical text:

tsv = 'дан':1 'магазин':2 'нужн':3 'посеща':4 'точн':5
tsq = 'нужн' & 'точн' & 'дан' & 'посещаем' & 'магазин'

SELECT
        (web_query_and @@ ts_title)::INTEGER AS full_title_entries, -- 0 / supposed 1
        (web_query_and @@ 'зачем нужны точные данные о посещаемости магазинов?')::INTEGER AS full_title_entries2,
        *
FROM
        (SELECT
                to_tsvector('russian', STRIP(to_tsvector('russian', 'зачем нужны точные данные о посещаемости
магазинов?'))::TEXT) AS ts_title, 
                websearch_to_tsquery('russian', REPLACE('зачем нужны точные данные о посещаемости магазинов?', '- ' ,
''))AS web_query_and 

        ) AS main

--
Best regards,
Roman

Hello

On 2/19/2020 5:35 PM, egocenter wrote:
> Text search doesn't work correct with the EQUAL string in text and query (russian dictionary config),
> as you can see in example ts_vector receives different from ts_query lexemes for identical text:
> 
> tsv = 'дан':1 'магазин':2 'нужн':3 'посеща':4 'точн':5
> tsq = 'нужн' & 'точн' & 'дан' & 'посещаем' & 'магазин'

It is because you call to_tsvector() two times. 'russian' is a Snowball 
dictionary and it uses stemming algorithms to cut words ending. Your 
query works if to_tsvector() isn't called twice on the same text:

=# SELECT
   web_query_and @@ ts_title,
   web_query_and @@ 'зачем нужны точные данные о посещаемости магазинов',
   *
FROM
   (SELECT
     to_tsvector('russian', 'зачем нужны точные данные о посещаемости 
магазинов') AS ts_title,
     websearch_to_tsquery('russian', 'зачем нужны точные данные о 
посещаемости магазинов?') AS web_query_and
   ) AS main;

It gives 'true' for the first column.

-- 
Artur

Hello, Artur!

Thanks for the answer,
ok, it's strange that only 1 word is affected that way (as if two lexemes exist for 1 word)...

*I use double to_tsvector to eliminate words duplicates.
in the example below ts_title = 'histori':2 'watcom':1,3
and it gives 2 entries in 'город - watcom' via ts_rank_cd

I need to count UNIQUE words entries but it seems to be no luck with std functionality
(I see 2 ways: custom ts_rank function OR to_tsvector / edit tsvector and leave only first position for 'watcom':
ts_title = 'histori':2 'watcom':1).

If you have any idea on that situation, I would highly appreciate it! Thanks in advance)

---------
SELECT
        round((ts_rank_cd(ts_title, web_query_or)/0.1)::NUMERIC, 0) AS title_entries_count, -- 2, but should be 1
   *
FROM
   (SELECT
     to_tsvector('russian', 'watcom history | watcom') AS ts_title,
     websearch_to_tsquery('russian', REPLACE('город - watcom', '- ' , '')) AS web_query_and, -- тире заменено для
отменыего конвертации в отрицание ! 
     REPLACE(websearch_to_tsquery(:reg_config, REPLACE('город - watcom', '- ' , ''))::TEXT, '&', '|')::tsquery AS
web_query_or 

   ) AS main;

--



   > Hello

> On 2/19/2020 5:35 PM, egocenter wrote:
>> Text search doesn't work correct with the EQUAL string in text and query (russian dictionary config),
>> as you can see in example ts_vector receives different from ts_query lexemes for identical text:
>>
>> tsv = 'дан':1 'магазин':2 'нужн':3 'посеща':4 'точн':5
>> tsq = 'нужн' & 'точн' & 'дан' & 'посещаем' & 'магазин'

> It is because you call to_tsvector() two times. 'russian' is a Snowball
> dictionary and it uses stemming algorithms to cut words ending. Your
> query works if to_tsvector() isn't called twice on the same text:

> =# SELECT
>    web_query_and @@ ts_title,
>    web_query_and @@ 'зачем нужны точные данные о посещаемости магазинов',
>    *
> FROM
>    (SELECT
>      to_tsvector('russian', 'зачем нужны точные данные о посещаемости
> магазинов') AS ts_title,
>      websearch_to_tsquery('russian', 'зачем нужны точные данные о
> посещаемости магазинов?') AS web_query_and
>    ) AS main;

> It gives 'true' for the first column.