show parameter optimizer_features : SHOW ALL « SQL PLUS Session Environment « Oracle PL/SQL Tutorial

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2. SQL PLUS Session Environment
3. SHOW ALL

SQL> create table t as select * from all_objects;
SQL>
SQL> create or replace function get_row_cnt return number
  2  as
  3          countValue   number;
  4  begin
  5          select count(*) into countValue from t;
  6          return countValue;
  7  end;
  8  /
SQL>
SQL> show parameter optimizer_features
                                                              

NAME                                  TYPE         VALUE
------------------------------------  -----------  ------------------------------
optimizer_features_enable             string       8.1.5
SQL>
SQL> alter session set sql_trace=true;
SQL>
SQL>
SQL> exec dbms_output.put_line( get_row_cnt );
12583
SQL>
SQL> alter system
  2  set optimizer_features_enable = '8.1.5' scope = spfile;
SQL>
SQL> drop table t;
SQL>