Want to index words more than 2 letters

Question

Hi All:
Can anyone help me with this? I have set the prefix preference, min length to be 3.
But it does not work. Any ideas? Appreciate your help.
Thanks
Nahmeh

Answer 1

I believe that setting the minimum prefix length to 3 will cause it to index the first 3 or more characters of words that may be used in wild-card searches, but it will still index whole words with only 1 or 2 characters. You can use a stoplist and add all possible combinations of one or two letters, as shown below.
scott@ORA92> create table test_tab (test_col varchar2(80))
  2  /
Table created.
scott@ORA92> insert all
  2  into test_tab values ('testing words like a I with one letter')
  3  into test_tab values ('testing words like an in of on or us be we to with two letters')
  4  into test_tab values ('testing some non-words ab bc cd de zx with two letters')
  5  select * from dual
  6  /
3 rows created.
scott@ORA92> begin
  2    ctx_ddl.create_stoplist ('mystoplist', 'BASIC_STOPLIST');
  3    for i in 1 ..26 loop
  4        ctx_ddl.add_stopword ('mystoplist', chr(96+i));
  5        for j in 1 .. 26 loop
  6          ctx_ddl.add_stopword ('mystoplist', chr(96+i) || chr(96+j));
  7        end loop;
  8    end loop;
  9  end;
10  /
PL/SQL procedure successfully completed.
scott@ORA92> create index test_idx on test_tab (test_col)
  2  indextype is ctxsys.context
  3  parameters ('stoplist mystoplist')
  4  /
Index created.
scott@ORA92> select token_text from dr$test_idx$i
  2  /
TOKEN_TEXT
LETTER
LETTERS
LIKE
NON
ONE
SOME
TESTING
TWO
WITH
WORDS
10 rows selected.
scott@ORA92>