11g [ SQL PLAN BASELINES ] LOOK UP ISSUE

Question

Hello everyone,
Working on 11g R1/windows
I'm trying to reltrieve some sql plan baselines, but nothing airs. The following is my configuration
SQL> show parameter compatible
NAME TYPE VALUE
compatible string 11.1.0.0.0
SQL> show parameter optimizer
NAME TYPE VALUE
optimizer_capture_sql_plan_baselines boolean TRUE
optimizer_dynamic_sampling integer 2
optimizer_features_enable string 11.1.0.6
optimizer_index_caching integer 0
optimizer_index_cost_adj integer 100
optimizer_mode string ALL_ROWS
optimizer_secure_view_merging boolean TRUE
optimizer_use_invisible_indexes boolean FALSE
optimizer_use_pending_statistics boolean FALSE
optimizer_use_sql_plan_baselines boolean TRUE
SQL> show parameter statistics
NAME TYPE VALUE
optimizer_use_pending_statistics boolean FALSE
statistics_level string ALL
timed_os_statistics integer 5
timed_statistics boolean TRUE
SQL> SELECT /*+ full(t) */ count(pad) FROM t WHERE n = 42;
COUNT(PAD)
1
SQL> SELECT * FROM table(dbms_xplan.display_cursor);
PLAN_TABLE_OUTPUT
SQL_ID 659q28x85bkn7, child number 1
SELECT /*+ full(t) */ count(pad) FROM t WHERE n = 42
Plan hash value: 2966233522
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | | | 23 (100)| |
| 1 | SORT AGGREGATE | | 1 | 505 | | |
PLAN_TABLE_OUTPUT
|* 2 | TABLE ACCESS FULL| T | 1 | 505 | 23 (0)| 00:00:01 |
Predicate Information (identified by operation id):
2 - filter("N"=42)
Why I'm getting the following result?
SQL> select count(*) from dba_sql_plan_baselines;
COUNT(*)
0
SQL> SELECT sql_handle, plan_name
2 FROM dba_sql_plan_baselines;
no rows selected
*Normally the view dba_sql_plan_baselines shouldn't be empty, when seeing the following parameter set?
*optimizer_capture_sql_plan_baselines boolean     TRUE
statistics_level ALL
Thank you for your help

Answer 1

Perhaps, because you executed your statement only once?
(I assume, you are reading the Christian Antognini's book - in that case you can read about it on page 292)
Best regards
Maxim