Progressive relaxation doesn't progress

Question

I just discovered that in a contains() query with a <progression> tag and multiple <seq> conditions, the query does not return any results (ie, does not evaluate any subsequent conditions) if the first condition fails (ie, returns no rows).
Is this the correct behavior? It seems like a bug to me. I dont see it mentioned in the documentation anywhere.
Thanks,
Rory

Answer 1

If you use a ctxcat index and catsearch, instead of a context index and contains, the optimizer uses the domain index and returns the correct results quickly, as shown in the comparison below. The only bad thing about catsearch is that, as far as I know, the score function doesn't work with it.
SCOTT@10gXE> CREATE TABLE presidents
  2    (id   NUMBER,
  3       name VARCHAR2(60))
  4  /
Table created.
SCOTT@10gXE> INSERT INTO presidents VALUES (1, 'William Jefferson Clinton')
  2  /
1 row created.
SCOTT@10gXE> BEGIN
  2    FOR i IN 1 .. 40 LOOP
  3        INSERT INTO presidents
  4        SELECT object_id, object_name
  5        FROM     all_objects;
  6    END LOOP;
  7  END;
  8  /
PL/SQL procedure successfully completed.
SCOTT@10gXE> SELECT COUNT(*) FROM presidents
  2  /
  COUNT(*)
    481081
SCOTT@10gXE> CREATE INDEX presidents_idx
  2  ON presidents (name)
  3  INDEXTYPE IS CTXSYS.CONTEXT
  4  /
Index created.
SCOTT@10gXE> EXEC DBMS_STATS.GATHER_TABLE_STATS ('SCOTT', 'PRESIDENTS')
PL/SQL procedure successfully completed.
SCOTT@10gXE> SET TIMING ON
SCOTT@10gXE> SET AUTOTRACE ON EXPLAIN
SCOTT@10gXE> select id, name
  2  from   presidents
  3  where  contains(name,
  4                  '<query>
  5                  <textquery>
  6                    <progression>
  7                      <seq>{William} {Clinton}</seq>
  8                      <seq>{William} ; {Clinton}</seq>
  9                    </progression>
10                  </textquery>
11                   </query>',1) <> 0
12  /
        ID NAME
         1 William Jefferson Clinton
Elapsed: 00:01:35.74
Execution Plan
Plan hash value: 3740813417
| Id  | Operation         | Name       | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT  |            | 23933 |   514K|   746  (35)| 00:00:09 |
|*  1 |  TABLE ACCESS FULL| PRESIDENTS | 23933 |   514K|   746  (35)| 00:00:09 |
Predicate Information (identified by operation id):
   1 - filter("CTXSYS"."CONTAINS"("NAME",'<query>
              <textquery>                       <progression>
              <seq>{William} {Clinton}</seq>                         <seq>{William} ;
              {Clinton}</seq>                       </progression>
               </textquery>                   </query>',1)<>0)
SCOTT@10gXE> SET TIMING OFF
SCOTT@10gXE> SET AUTOTRACE OFF
SCOTT@10gXE> DROP INDEX presidents_idx
  2  /
Index dropped.
SCOTT@10gXE> CREATE INDEX presidents_idx
  2  ON presidents (name)
  3  INDEXTYPE IS CTXSYS.CTXCAT
  4  /
Index created.
SCOTT@10gXE> EXEC DBMS_STATS.GATHER_TABLE_STATS ('SCOTT', 'PRESIDENTS')
PL/SQL procedure successfully completed.
SCOTT@10gXE> SET TIMING ON
SCOTT@10gXE> SET AUTOTRACE ON EXPLAIN
SCOTT@10gXE> select id, name
  2  from   presidents
  3  where  catsearch(name,
  4                  '<query>
  5                  <textquery>
  6                    <progression>
  7                      <seq>{William} {Clinton}</seq>
  8                      <seq>{William} ; {Clinton}</seq>
  9                    </progression>
10                  </textquery>
11                   </query>',null) > 0
12  /
        ID NAME
         1 William Jefferson Clinton
Elapsed: 00:00:01.94
Execution Plan
Plan hash value: 777849224
| Id  | Operation                   | Name           | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT            |                | 24160 |   519K|   486   (1)| 00:00:06 |
|   1 |  TABLE ACCESS BY INDEX ROWID| PRESIDENTS     | 24160 |   519K|   486   (1)| 00:00:06 |
|*  2 |   DOMAIN INDEX              | PRESIDENTS_IDX |       |       |            |          |
Predicate Information (identified by operation id):
   2 - access("CTXSYS"."CATSEARCH"("NAME",'<query>                     <textquery>
                                 <progression>                         <seq>{William}
              {Clinton}</seq>                         <seq>{William} ; {Clinton}</seq>
                       </progression>                     </textquery>
              </query>',NULL)>0)
SCOTT@10gXE>