How can to_tsquery() return a value that does not match the searched value?

Question

Can someone explain to me how this:

SELECT description, description_search
FROM my_table 
WHERE description_search @@ to_tsquery('ins:*')

can return this:

description: 
'The leap second configuration has been updated.
Reason: Leap second data initialized from registry during boot
Leap seconds enabled: true
New leap second count: 0
Old leap second count: 0'

description_search:
'0':25,30 'boot':16 'configur':4 'count':24,29 'data':11 'enabl':19 'initi':12 
'leap':2,9,17,22,27 'new':21 'old':26 'reason':8 'registri':14 'second':3,10,18,23,28 
'true':20 'updat':7

when no words in the returned string matches 'ins:*'?

Answer 1

Look at what to_tsquery returns.

select to_tsquery('ins:*');
 to_tsquery 
------------
 'in':*
(1 row)

So 'ins:' gets stemmed to 'in:' (for English anyway), and 'in:*' obviously matches 'initi'

Don't use to_tsquery() if you have already written the query yourself. Just use the query your wrote, 'ins:*'::tsquery