Re: Text search prefix matching and stop words

>
> Prefix matching should not omit stop words, as matching lexemes may
> legitimately begin with stop words.
>
> # select to_tsquery('english', 'over:*') @@ to_tsvector('english',
> 'overhaul');
> NOTICE: text-search query contains only stop words or doesn't contain
> lexemes, ignored
> ?column?
> ----------
> f
> (1 row)
>
> I noticed this after implementing interactive, incremental search in an
> application. As the user typed "overhaul," with each successive character
> executing a search, "ove" and "overh" matched a particular document, but
> "over" did not.

Big thanks for the reporting!

I am not sure that it is a bug. I think this is a way how to_tsquery
conversion work: stopwords first then template processing.

If you want to process successive characters typing, you can use casting to
tsvector type until input is not finished

'over:*'::tsquery;

and when the user finishes input then process the result via to_tsquery
with stop words.

if we do to_tsquery in a way you described I expect it will never apply the
stop-word filter on templated input as it can not be compared to stop words.

--
Best regards,
Pavel Borisov

Postgres Professional: http://postgrespro.com <http://www.postgrespro.com>