Not sure if a bug or if I'm missing something but this query produces weird results with TRIM and TRIM: SELECT DISTINCT TRIM(TRAILING FROM 'cnam_lpp_histo_io','_io')
The devil is in the details. Trim won't remove the string "_io", it'll trim off the characters "_", "i" and "o". And with that logic, the "o" at the end of "histo" is correctly removed as well.