 |
 |
 |
 |
 |
|||
 |
|||
 |
|||
 |
|||
 |
|||
 |
|||
 |
|||
 |
|||
 |
|||
 |
|||
 |
|||
 |
|||
 |
|||
 |
|||
 |
|||
 |
|||
 |
|||
 |
|||
 |
|||
|
|||
 |
|||
|
|||
 |
|||
|
|||
 |
Donald K. Burleson Oracle Utilities Tips |
Simple Tracing With autotrace
The autotrace utility is a very underutilized feature of SQL*Plus. It
offers statement tracing and instant feedback on any successful SELECT,
INSERT, UPDATE or DELETE statement. The utility requires a plan table (for
the Explain Plan) under the current user’s schema. In addition, it requires
the plustrace or DBA role for the user executing the trace. The source for
the PLUSTRACE role can be found in
$ORACLE_HOME/sqlplus/admin/plustrce.sql.
Tracing is enabled via the set autotrace command in SQL*Plus:
SQL> set autotrace on
SQL> select ename from emp where empno = 1122;
no rows selected
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE
1 0 TABLE ACCESS (BY INDEX ROWID) OF 'EMP'
2 1 INDEX (UNIQUE SCAN) OF 'PK_EMP' (UNIQUE)
Statistics
----------------------------------------------------------
83 recursive calls
0 db block gets
21 consistent gets
3 physical reads
0 redo size
221 bytes sent via SQL*Net to client
368 bytes received via SQL*Net from client
1 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
0 rows processed
autotrace provides instantaneous feedback including the returned rows,
execution plan, and statistics. The user doesn’t need to be concerned about
trace file locations and formatting since the output is displayed instantly
on the screen. This is very important data that can be used to tune the SQL
statement.
autotrace supports the following options:
• on – Enables all options.
• on explain – Displays returned rows and the explain plan.
• on statistics – Displays returned rows and statistics.
• trace explain – Displays the execution plan for a select statement
without actually executing it.
set autotrace trace explain
• traceonly – Displays execution plan and statistics without displaying the
returned rows. This option should be used when a large result set is
expected.
autotrace is so easy to use that it should be the first tracing utility
used for most SQL performance tuning issues. tkprof can be used for more
detailed analysis.
For DBAs requiring the lowest level debugging – oradebug, described in the
next section, will do the job.
The above is an excerpt from Oracle Utilities - Using
Hidden Programs, Import/Export, SQL Loader, oradebug, Dbverify, Tkprof
and More by Rampant TechPress (Dave Moore).
It’s only $19.95 and you can order the
book and get instant access to the online Oracle utilities scripts:
http://www.rampant-books.com/book_2003_1_utils.htm
http://rampant-books.com/book_2003_2_audit.htm
Download your Oracle scripts now: The definitive Oracle Script collection for every Oracle professional DBA |
|
|
