How to give more relevance to one of the column in multicolumn datastore

Question

Hi Gurus,
While using multicolumn datastore needed to give more importance to one of the column than the other one. How can we achieve the same ?
SQL> create table test_sh4 (text1 clob,text2 clob);
Table created.
SQL> alter table test_sh4 add (text3 clob);
Table altered.
SQL> begin
2 ctx_ddl.create_preference ('nd_mcd', 'multi_column_datastore');
3 ctx_ddl.set_attribute
4 ('nd_mcd',
5 'columns',
6 'replace (text1, '' '', '''') nd, text1 text1,replace (text1, '' '', '''') nd, text1 text1');
7 ctx_ddl.set_attribute ('nd_mcd', 'delimiter', 'newline');
8 ctx_ddl.create_preference ('test_lex1', 'basic_lexer');
9 ctx_ddl.set_attribute ('test_lex1', 'whitespace', '/\|-_+');
10 end;
11 /
PL/SQL procedure successfully completed.
SQL> create index IX_test_sh4 on test_sh4 (text3)
indextype is ctxsys.context
parameters
('datastore nd_mcd
lexer test_lex1')
/ 2 3 4 5 6
Index created.Here while querying how can I give more relevance to text1 column than text2 column ?

Answer 1

Every time that you post code, whatever you are using eliminates all formatting and changes any multiple spaces to single spaces, so it makes it hard to tell what your code really is. Within the function, you need to remove the special characters and double spaces before you use the string for anything else. In the first part of your output string, you were only putting a % in front of the first word and after the last word. I fixed it so that it puts % before and after every word. I also added some code to return a score of 100 when an exact match is found in any column. You can use the function in a select from dual to see what it is returning. Please see the demonstration below. I will provide a copy of the function in a separate post that you can copy and paste. You may want to adjust the values that you multiply by. The values of 10 and 5 and .5 and .1 were just examples.
SCOTT@orcl_11gR2> create table test_sh (text1 clob,text2 clob);
Table created.
SCOTT@orcl_11gR2> alter table test_sh add (text3 clob);
Table altered.
SCOTT@orcl_11gR2> insert all
  2  into test_sh (text1, text2, text3)
  3    values ('staple card', 'word2', 'word3')
  4  into test_sh (text1, text2, text3)
  5    values ('word4', 'staple card', 'word5')
  6  into test_sh (text1, text2, text3)
  7    values ('staplecard', 'word2', 'word3')
  8  into test_sh (text1, text2, text3)
  9    values ('word4', 'staplecard', 'word5')
10  into test_sh (text1, text2, text3) values
11    ('Weber Genesis S-310 Gas Grill',
12       'Weber Genesis S-310 Gas Grill',
13       'Weber Genesis S-310 Gas Grill')
14  select * from dual
15  /
5 rows created.
SCOTT@orcl_11gR2> begin
  2    ctx_ddl.create_preference ('nd_mcd', 'multi_column_datastore');
  3    ctx_ddl.set_attribute
  4        ('nd_mcd',
  5         'columns',
  6         'replace (text1, '' '', '''') nd1,
  7          text1 text1,
  8          replace (text2, '' '', '''') nd2,
  9          text2 text2');
10    ctx_ddl.create_preference ('test_lex1', 'basic_lexer');
11    ctx_ddl.set_attribute ('test_lex1', 'whitespace', '/\|-_+');
12    ctx_ddl.create_section_group ('test_sg', 'basic_section_group');
13    ctx_ddl.add_field_section ('test_sg', 'text1', 'text1', true);
14    ctx_ddl.add_field_section ('test_sg', 'nd1', 'nd1', true);
15    ctx_ddl.add_field_section ('test_sg', 'text2', 'text2', true);
16    ctx_ddl.add_field_section ('test_sg', 'nd2', 'nd2', true);
17  end;
18  /
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> create index IX_test_sh on test_sh (text3)
  2  indextype is ctxsys.context
  3  parameters
  4    ('datastore     nd_mcd
  5        lexer          test_lex1
  6        section group     test_sg')
  7  /
Index created.
SCOTT@orcl_11gR2> create or replace function text_format
  2    (p_string in varchar2)
  3    return         varchar2
  4  as
  5    v_string     varchar2 (32767);
  6    v_string_out varchar2 (32767);
  7    v_string_in1 varchar2 (32767);
  8    v_string_in2 varchar2 (32767);
  9    V_TOKEN         VARCHAR2 (32767);
10  BEGIN
11    -- remove special characters and double spaces before using in anything else:
12    v_string := trim (translate (p_string, '/\|-_+&', '      '));
13    v_string := replace (v_string, '''', '');
14    while instr (v_string, '  ') > 0 loop
15        v_string := replace (v_string, '  ', ' ');
16    end loop;
17    -- fixed 2 lines below:
18    v_string_out := '(%' || replace (v_string, ' ', '% %') || '%) ' || ',';
19    v_string_out := v_string_out || '(' || v_string || ')' || ',';
20    -- first search string with spaces:
21    v_string_in1 := v_string || ' ';
22    -- second search string without spaces:
23    v_string_in2 := replace (v_string_in1, ' ', '') || ' ';
24    if v_string_in2 = v_string_in1 then
25        v_string_in2 := null;
26    end if;
27    -- format search string one token at a time:
28    while v_string_in1 is not null loop
29        v_token := substr (v_string_in1, 1, instr (v_string_in1, ' ') - 1);
30        v_string_out := v_string_out
31        || '('
32        || '?' || v_token || ' or '
33        || '!' || v_token || ' or '
34        || '$' || v_token
35        || '),';
36        v_string_in1 := substr (v_string_in1, instr (v_string_in1, ' ') + 1);
37    end loop;
38    while v_string_in2 is not null loop
39        v_token := substr (v_string_in2, 1, instr (v_string_in2, ' ') - 1);
40        v_string_out := v_string_out
41        || '('
42        || '%' || v_token || '% or '
43        || '?' || v_token || ' or '
44        || '!' || v_token || ' or '
45        || '$' || v_token
46        || '),';
47        v_string_in2 := substr (v_string_in2, instr (v_string_in2, ' ') + 1);
48    end loop;
49    -- return formatted string (added score of 100 for exact match in any column:
50    return
51        '(' || v_string            || ') * 10 * 10 or
52         (' || rtrim (v_string_out, ',') || ' within text1) * 10 or
53         (' || rtrim (v_string_out, ',') || ' within nd1) * 5 or
54         (' || rtrim (v_string_out, ',') || ' within text2) * .5 or
55         (' || rtrim (v_string_out, ',') || ' within nd2) * .1';
56  end text_format;
57  /
Function created.
SCOTT@orcl_11gR2> show errors
No errors.
SCOTT@orcl_11gR2> select text_format ('STAPLE CARD') from dual
  2  /
TEXT_FORMAT('STAPLECARD')
(STAPLE CARD) * 10 * 10 or
     ((%STAPLE% %CARD%) ,(STAPLE CARD),(?STAPLE or !STAPLE or $STAPLE),(?CARD or
!CARD or $CARD),(%STAPLECARD% or ?STAPLECARD or !STAPLECARD or $STAPLECARD) wit
hin text1) * 10 or
     ((%STAPLE% %CARD%) ,(STAPLE CARD),(?STAPLE or !STAPLE or $STAPLE),(?CARD or
!CARD or $CARD),(%STAPLECARD% or ?STAPLECARD or !STAPLECARD or $STAPLECARD) wit
hin nd1) * 5 or
     ((%STAPLE% %CARD%) ,(STAPLE CARD),(?STAPLE or !STAPLE or $STAPLE),(?CARD or
!CARD or $CARD),(%STAPLECARD% or ?STAPLECARD or !STAPLECARD or $STAPLECARD) wit
hin text2) * .5 or
     ((%STAPLE% %CARD%) ,(STAPLE CARD),(?STAPLE or !STAPLE or $STAPLE),(?CARD or
!CARD or $CARD),(%STAPLECARD% or ?STAPLECARD or !STAPLECARD or $STAPLECARD) wit
hin nd2) * .1
1 row selected.
SCOTT@orcl_11gR2> column text1 format a11
SCOTT@orcl_11gR2> column text2 format a11
SCOTT@orcl_11gR2> column text3 format a11
SCOTT@orcl_11gR2> SELECT SCORE(1), t.* FROM test_sh t
  2  WHERE  CONTAINS (text3, text_format ('STAPLE CARD'), 1) > 0
  3  ORDER  BY 1 DESC
  4  /
  SCORE(1) TEXT1       TEXT2       TEXT3
       100 staple card word2       word3
       100 word4       staple card word5
       100 staplecard  word2       word3
        10 word4       staplecard  word5
4 rows selected.