Contains return all the records when the query string matches the columns

Question

I used the multi_column_datastore preference and created an index on three columns (item_name, description,owner_part_number). Now if I do a search:
select * from items where contains(description, 'description') > 0;It returns all the rows in items table, but not all the rows have "description" as a word. I guess Oracle text assumes the query intends to get all the rows as the query string matches one of the column names. My question is whether Oracle Text has any preference settings to alter this behavior?
execute ctx_ddl.create_preference('item_multi_preference', 'MULTI_COLUMN_DATASTORE');
execute ctx_ddl.set_attribute('item_multi_preference', 'columns', 'item_name, description,owner_part_number');
create index item_text_index on items(description) indextype is ctxsys.context filter by owner parameters('LEXER ENG_LEXER WORDLIST ENG_WORDLIST STOPLIST CTXSYS.EMPTY_STOPLIST datastore item_multi_preference MEMORY 1024M');Thanks.
Jun Gao

Answer 1

It looks like a basic_section_group fixes the problem as well, as demonstrated below and I believe a basic_section_group may be more efficient than auto_section_group.
SCOTT@orcl_11gR2> -- recreation of problem:
SCOTT@orcl_11gR2> drop table items
  2  /
Table dropped.
SCOTT@orcl_11gR2> create table items (
  2       "ITEM_NAME"             varchar2(100 byte),
  3        "ITEM_NUMBER"              varchar2(100 byte),
  4        "DESCRIPTION"              varchar2(4000 byte),
  5        "OWNER" number
  6  )
  7  /
Table created.
SCOTT@orcl_11gR2> begin
  2    FOR Lcntr IN 1..100
  3    loop
  4         insert into items (item_name, item_number, description, owner)
  5         values (dbms_random.string('A', 10),
  6              dbms_random.string('A', 10),
  7              dbms_random.string('L', 8) || ' '
  8              || dbms_random.string('A', 4)
  9              || dbms_random.string('A', 5)  || ' '
10              || dbms_random.string('A', 10),
11              dbms_random.value(1,10) );
12    end loop;
13  end;
14  /
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> begin
  2    FOR Lcntr IN 1..100
  3    loop
  4         insert into items (item_name, item_number, description, owner)
  5         values (dbms_random.string('A', 10),
  6              dbms_random.string('A', 10),
  7              dbms_random.string('L', 8) || ' '
  8              || dbms_random.string('A', 4) || '111'
  9              || dbms_random.string('A', 5)  || ' '
10              || dbms_random.string('A', 10), 1234 );
11    end loop;
12  end;
13  /
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> exec ctx_ddl.drop_preference('ENG_WORDLIST');
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> begin
  2    ctx_ddl.create_preference('ENG_WORDLIST', 'BASIC_WORDLIST');
  3    ctx_ddl.set_attribute('ENG_WORDLIST','PREFIX_INDEX','TRUE');
  4    ctx_ddl.set_attribute('ENG_WORDLIST','PREFIX_MIN_LENGTH',1);
  5    ctx_ddl.set_attribute('ENG_WORDLIST','PREFIX_MAX_LENGTH',10);
  6    ctx_ddl.set_attribute('ENG_WORDLIST','SUBSTRING_INDEX','TRUE');
  7    ctx_ddl.set_attribute('ENG_WORDLIST','WILDCARD_MAXTERMS', 0);
  8  end;
  9  /
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> execute ctx_ddl.drop_preference('ENG_LEXER');
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> begin
  2    CTX_DDL.CREATE_PREFERENCE ('ENG_LEXER', 'BASIC_LEXER');
  3    CTX_DDL.SET_ATTRIBUTE ('ENG_LEXER', 'PRINTJOINS', '@-_');
  4  end;
  5  /
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> execute ctx_ddl.drop_preference('items_multi_preference');
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> begin
  2    ctx_ddl.create_preference('items_multi_preference', 'MULTI_COLUMN_DATASTORE');
  3    ctx_ddl.set_attribute('items_multi_preference', 'columns', 'item_name, description,item_number');
  4  end;
  5  /
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> create index items_text_index
  2  on items(description)
  3  indextype is ctxsys.context
  4  parameters
  5    ('LEXER         ENG_LEXER
  6        WORDLIST   ENG_WORDLIST
  7        STOPLIST   CTXSYS.EMPTY_STOPLIST
  8        datastore  items_multi_preference
  9        MEMORY     1024M')
10  /
Index created.
SCOTT@orcl_11gR2> create index owner_idx on items (owner)
  2  /
Index created.
SCOTT@orcl_11gR2> exec dbms_stats.gather_table_stats (user, 'ITEMS')
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> select count(*)
  2  from   items
  3  where  contains (description, 'description') > 0
  4  /
  COUNT(*)
       200
1 row selected.
SCOTT@orcl_11gR2> -- correction of problem:
SCOTT@orcl_11gR2> exec ctx_ddl.drop_section_group ('items_sec')
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> begin
  2    ctx_ddl.create_section_group ('items_sec', 'basic_section_group');
  3    ctx_ddl.add_field_section ('items_sec', 'item_name', 'item_name', true);
  4    ctx_ddl.add_field_section ('items_sec', 'description', 'description', true);
  5  end;
  6  /
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> drop index items_text_index
  2  /
Index dropped.
SCOTT@orcl_11gR2> create index items_text_index
  2  on items(description)
  3  indextype is ctxsys.context
  4  parameters
  5    ('LEXER         ENG_LEXER
  6        WORDLIST   ENG_WORDLIST
  7        STOPLIST   CTXSYS.EMPTY_STOPLIST
  8        datastore  items_multi_preference
  9        MEMORY     1024M
10        section group items_sec')
11  /
Index created.
SCOTT@orcl_11gR2> select count(*)
  2  from   items
  3  where  contains (description, 'description') > 0
  4  /
  COUNT(*)
         0
1 row selected.