dict_exclude is a postgresql extension which provides a dictionary which can be used to create stop words based on regular expressions.
At the time of writing it appears like a decent solution towards this goal, but it does not use the stop word facility in text search which effectively creates a sorted list of words.
The code is based largely on the excellent dictint example in postgresql/contrib.
git clone git@github.com:no0p/dict_exclude.git
make
sudo make install
Next create a list of exclusionary rules by adding a file exclude.rules in the postgresql text search resource directory. For example, with Postgresql 9.4 on ubuntu you might add the file /usr/share/postgresql/9.4/tsearch_data/exclude.rules.
The contents of the file are regular expressions, one per line:
abc
def
Then create the appropriate text search configuration in psql.
create text search configuration ocr_gibberish ( COPY = pg_catalog.english );
alter text search configuration ocr_gibberish
alter mapping for asciihword, asciiword
with dict_exclude, english_stem;
Note that dict_exclude must be the first entry in the with clause to work.
Now querying will achieve the desired results:
SELECT to_tsvector('ocr_gibberish', 'fat abc cat def abd');
to_tsvector
-------------------------
'abd':5 'cat':3 'fat':1
(1 row)
This is a prototype at the moment, so recommended for development environments only.