Prevent stemming of words starting with # in PostgreSQL full text search

Question

Basically, I want to be able to get an exact match (hashtag included) for queries like this:

=#SELECT to_tsvector('english', '#adoption');
 to_tsvector
-------------
 'adopt':1

Instead, I want for words starting with #, to see:

=#SELECT to_tsvector('english', '#adoption');
 to_tsvector
-------------
 '#adoption':1

Is this possible with psql full text search?

Answer 1

Before you search or index, you could replace each # character with some other character that you don't use in your texts, but which changes the parser's interpretation:

test=> SELECT alias, lexemes FROM ts_debug('english', '#adoption');
┌───────────┬─────────┐
│   alias   │ lexemes │
├───────────┼─────────┤
│ blank     │         │
│ asciiword │ {adopt} │
└───────────┴─────────┘
(2 rows)

test=> SELECT alias, lexemes FROM ts_debug('english', '/adoption');
┌───────┬─────────────┐
│ alias │   lexemes   │
├───────┼─────────────┤
│ file  │ {/adoption} │
└───────┴─────────────┘
(1 row)