Oracle Cite

Get current session id:

 

SELECT sid, serial#, username, machine

FROM v$session

WHERE type != 'BACKGROUND'

 

Enable & Disable sql trace:

 

dbms_monitor.session_trace_enable(session_id => 127,

                                  serial_num => 29,

                                  waits      => TRUE,

                                  binds      => FALSE)

 

dbms_monitor.session_trace_disable(session_id => 127,

                                   serial_num => 29)

 

Gather time statistics

ALTER SESSION SET timed_statistics = TRUE

 

Get trace file

SELECT value FROM v$diag_info WHERE name = 'Default Trace File';

 

General trprof usage

tkprof {input trace file} {output file} sys=no sort=prsela,exeela,fchela

prsela: elapsed time parsing.

 

 Gather table statistics:

 

BEGIN

  dbms_stats.gather_table_stats(ownname          => user,

                                tabname          => 'T',

                                estimate_percent => 100,

                                method_opt       => 'for all columns size skewonly',

                                cascade          => TRUE);

END;

/

 

Get statistic on table:

 

SQL> SELECT num_rows, blocks, empty_blocks, avg_space, chain_cnt, avg_row_len

  2  FROM user_tab_statistics

  3  WHERE table_name = 'T';

 

Get statistic on column:

 

SQL> SELECT column_name AS "NAME",

  2         num_distinct AS "#DST",

  3         low_value,

  4         high_value,

  5         density AS "DENS",

  6         num_nulls AS "#NULL",

  7         avg_col_len AS "AVGLEN",

  8         histogram,

  9         num_buckets AS "#BKT"

 10  FROM user_tab_col_statistics

 11  WHERE table_name = 'T';

 

 

 

 

Gain explain plan:

 SQL> EXPLAIN PLAN FOR SELECT * FROM emp WHERE deptno = 10 ORDER BY ename;

SQL> SELECT * FROM table(dbms_xplan.display);

 

SQL> SELECT * FROM table(dbms_xplan.display(NULL,NULL,'typical'));