Search for exact match without additional words

Question

Hi everybody,
is it possible to find out if a tag contains a certain word or phrase and nothing else? E.g. the search for all documents with the title "foo" should match all documents containing <title>foo</title> but not documents that contain something like <title>foo bar</title>. I tried something like "( foo ~ ( % ~ foo ) ) WITHIN title" but I get a "wildcard query expansion resulted in too many terms" error, so using a wildcard is no option here. Any ideas?

Answer 1

Another method would be to use extractvalue to limit the rows. It would still use the text index to get the rows with foo in it, then extractvalue would limit it to just those rows where only the word foo is in it. This would eliminate the need for a procedure or user_datastore or increasing the index size. Please see the demonstration below.
SCOTT@orcl_11gR2> create table documents
  2    (text  varchar2 (45))
  3  /
Table created.
SCOTT@orcl_11gR2> insert all
  2  into documents values ('<title>foo</title>')
  3  into documents values ('<title>foo bar</title>')
  4  into documents values ('<title>bar foo</title>')
  5  select * from dual
  6  /
3 rows created.
SCOTT@orcl_11gR2> insert into documents
  2  select '<title>' || object_name || '</title>'
  3  from   all_objects
  4  /
76012 rows created.
SCOTT@orcl_11gR2> create index test_idx
  2  on documents (text)
  3  indextype is ctxsys.context
  4  parameters
  5    ('section group ctxsys.auto_section_group')
  6  /
Index created.
SCOTT@orcl_11gR2> set autotrace on explain
SCOTT@orcl_11gR2> select * from documents d
  2  where  contains (text, 'foo within title') > 0
  3  and    extractvalue (xmltype (d.text), '//title') = 'foo'
  4  /
TEXT
<title>foo</title>
1 row selected.
Execution Plan
Plan hash value: 3102160860
| Id  | Operation                   | Name      | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT            |           |     1 |    36 |    10   (0)| 00:00:01 |
|*  1 |  TABLE ACCESS BY INDEX ROWID| DOCUMENTS |     1 |    36 |    10   (0)| 00:00:01 |
|*  2 |   DOMAIN INDEX              | TEST_IDX  |       |       |     4   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - filter(EXTRACTVALUE("XMLTYPE"."XMLTYPE"("D"."TEXT"),'//title')='foo')
   2 - access("CTXSYS"."CONTAINS"("TEXT",'foo within title')>0)
Note
   - dynamic sampling used for this statement (level=2)
SCOTT@orcl_11gR2>