Is result_cache working in Oracle 11.1.0.6.0?

Question

BANNER
Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production
PL/SQL Release 11.1.0.6.0 - Production
CORE 11.1.0.6.0 Production
TNS for Solaris: Version 11.1.0.6.0 - Production
NLSRTL Version 11.1.0.6.0 - Production
SQL> SELECT dbms_result_cache.status() FROM dual;
DBMS_RESULT_CACHE.STATUS()
--------------------------------------------------------------------------------------------------------------------------------------------------------------------ENABLED
12:31:08 SQL> set autotrace on
select count(*) from objs;
12:31:27 SQL>
COUNT(*)
69918
Elapsed: 00:00:01.72
Execution Plan
Plan hash value: 386529197
| Id | Operation | Name | Rows | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | 1 | 289 (1)| 00:00:04 |
| 1 | SORT AGGREGATE | | 1 | | |
| 2 | TABLE ACCESS FULL| OBJS | 80773 | 289 (1)| 00:00:04 |
Note
- dynamic sampling used for this statement
Statistics
282 recursive calls
0 db block gets
1140 consistent gets
1038 physical reads
0 redo size
524 bytes sent via SQL*Net to client
524 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
5 sorts (memory)
0 sorts (disk)
1 rows processed
12:31:49 SQL> select /*+ result_cache */ count(*) from objs;
COUNT(*)
69918
Elapsed: 00:00:00.03
Execution Plan
Plan hash value: 386529197
| Id | Operation | Name | Rows | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | 1 | 289 (1)| 00:00:04 |
| 1 | RESULT CACHE | cnsc9rw3p17364cbg4975pad6y | | | |
| 2 | SORT AGGREGATE | | 1 | | |
| 3 | TABLE ACCESS FULL| OBJS | 80773 | 289 (1)| 00:00:04 |
Result Cache Information (identified by operation id):
1 - column-count=1; dependencies=(CTSGKOD.OBJS); attributes=(single-row); name="select /*+ result_cache */ count(*) from objs"
Note
- dynamic sampling used for this statement
Statistics
4 recursive calls
0 db block gets
1110 consistent gets
0 physical reads
0 redo size
524 bytes sent via SQL*Net to client
524 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
12:32:06 SQL>
i see result_cache in execution plan, but why do i see 1110 consistent gets? I expected 0 in consisent gets and physical reads and the query is not executed ...
Thank You

Answer 1

Aman,
lets say i run these statements
1) exec dbms_result_cache.flush
2) alter system flush shared_pool;
3)alter system flush buffer_cache;
Then i run the query without hint of result_cache
4) Select count(*) from objs; --> This query is not using result cache, it is running for first time, so physical reads & consistent gets
5) select count(*) from objs; --> again same query, this time only consistent gets
6) select /*+ result_cache */ count(*) from objs; -- Lets introduce result_cache now
Will the above query gets data from buffer cache or will it use result_cache and gets result from memory instead of running query? Or will this 6th statement run same as (5) and prepares ground for usage of result_cache and
any other queries later can benefit from result_cache?
Thanks again Aman