Useful SQL commands

SELECT * from table(dbms_xplan.display)

Spool filename with timestamp

set termout off
column c_filename new_value VAR_FILENAME
select 'any_logfile_name_' || to_char(sysdate,'YYYYMMDD_HH24MISS') c_filename from dual;
spool &&VAR_FILENAME
set trimspool on
select user from dual;
spool off

execute dbms_system.set_sql_trace_in_session(sid,serial,true);

v$cache
v$buffer_pool
v$bh
v$db_cache_advice