Performance of resource view using domain index XDBHI_IDX

Question

Hello all,
We have a home grown XMLDB application for doing schema validation against incoming messages. The application issues several queries like below. I know, it hard parses, which is very bad, but that's not where the real performance problem is right now. The problem is with the domain index XDBHI_IDX against the xdb$resource table. We use a very specific path which results in 0 or 1 returned rows, but as you can see the domain index has an intermediate result of 48041 rows, so the index is not effective here. Statistics are up to date, the index has been rebuild. Does anybody know what we can do with the domain index to make it do what it should do: identify the one xml document in that path?
SELECT 0
FROM
resource_view WHERE any_path=
  '/home/app/incoming/ARCH_IN/2012/01/592174'
call     count       cpu    elapsed       disk      query    current        rows
Parse        2      0.02       0.02          0       1041          0           0
Execute      2      0.00       0.00          0          0          0           0
Fetch        2     81.26      85.43          0     202556     576158           0
total        6     81.28      85.45          0     203597     576158           0
Misses in library cache during parse: 1
Optimizer mode: ALL_ROWS
Parsing user id: 67  (app)   (recursive depth: 3)
Rows     Row Source Operation
      0  TABLE ACCESS BY INDEX ROWID XDB$RESOURCE (cr=341531 pr=0 pw=0 time=60883725 us)
  48041   DOMAIN INDEX  XDBHI_IDX (cr=311030 pr=0 pw=0 time=1548774 us)Regards,
Rob.
PS: Database version is 10.2.0.3.0

Answer 1

Hi odie and Marco,
Thanks for your tips. Using equals_path instead of "=" did the trick indeed. Here are some results from our test system to prove it.
Old query:
SQL> SELECT /*+ gather_plan_statistics */ 0
  2  FROM
  3   resource_view WHERE any_path=
  4    '/home/app/incoming/ARCH_IN/2012/01/592174'
  5  /
no rows selected
SQL> select *
  2    from table(dbms_xplan.display_cursor(null,null,'allstats last'))
  3  /
PLAN_TABLE_OUTPUT
SQL_ID  0cnfnzqc2k5bd, child number 0
SELECT /*+ gather_plan_statistics */ 0 FROM  resource_view WHERE any_path=
'/home/app/incoming/ARCH_IN/2012/01/592174'
Plan hash value: 2859544236
| Id  | Operation                   | Name         | Starts | E-Rows | A-Rows |   A-Time   | Buffers |
|*  1 |  TABLE ACCESS BY INDEX ROWID| XDB$RESOURCE |      1 |      1 |      0 |00:00:00.15 |   12104 |
|*  2 |   DOMAIN INDEX              | XDBHI_IDX    |      1 |        |   2590 |00:00:00.10 |   10576 |
Predicate Information (identified by operation id):
   1 - filter("XDB"."ABSPATH"(9999)='/home/app/incoming/ARCH_IN/2012/01/592174')
   2 - access("XDB"."UNDER_PATH"("P"."SYS_NC00033$",'/',9999)=1)
20 rows selected.New query:
SQL> SELECT /*+ gather_plan_statistics */ 0
  2  FROM
  3   resource_view
  4  where equals_path(res, '/home/app/incoming/ARCH_IN/2012/01/592174') = 1
  5  /
no rows selected
SQL> select *
  2    from table(dbms_xplan.display_cursor(null,null,'allstats last'))
  3  /
PLAN_TABLE_OUTPUT
SQL_ID  b8y3sra82yj7u, child number 0
SELECT /*+ gather_plan_statistics */ 0 FROM  resource_view where
equals_path(res, '/home/app/incoming/ARCH_IN/2012/01/592174') = 1
Plan hash value: 3533888242
| Id  | Operation     | Name      | Starts | A-Rows |   A-Time   | Buffers |
|*  1 |  DOMAIN INDEX | XDBHI_IDX |      1 |      0 |00:00:00.01 |       2 |
Predicate Information (identified by operation id):
   1 - access("XDB"."EQUALS_PATH"("P"."SYS_NC00033$",'/home/app/incoming
              /ARCH_IN/2012/01/592174')=1)Regards,
Rob.