Does plan_table cleared or purged automatically?

Question

what is the restriction or limitation of using plan_table? Any links would be appreciated too!
I am referring to the default plan_table!
Thanks

Answer 1

As stated in the docs, the PLAN_TABLE is automatically created as a global temporary table, so as a consequence that data is lost when the session is ended as it was private to the session.
[Plan Table Docs|http://www.oracle.com/pls/db112/to_URL?remark=ranked&urlname=http:%2F%2Fdownload.oracle.com%2Fdocs%2Fcd%2FE11882_01%2Fserver.112%2Fe10821%2Fex_plan.htm%23PFGRF94674]
Connected to Oracle Database 11g Enterprise Edition Release 11.1.0.6.0
Connected as fsitja
SQL> explain plan for select 1 from dual;
Explained
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
Plan hash value: 1388734953
| Id  | Operation        | Name | Rows  | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT |      |     1 |     2   (0)| 00:00:01 |
|   1 |  FAST DUAL       |      |     1 |     2   (0)| 00:00:01 |
8 rows selected
SQL> disc
Not logged on
SQL> conn fsitja/xxxxxxxxx@ORCL
Connected to Oracle Database 11g Enterprise Edition Release 11.1.0.6.0
Connected as fsitja
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
Error: cannot fetch last explain plan from PLAN_TABLE
SQL> select count(*) from plan_table;
  COUNT(*)
         0
SQL>