ORACLE set autotrace

set autotrace off
set autotrace on
set autotrace traceonly

set autotrace on explain
set autotrace on statistics
set autotrace on explain statistics

set autotrace traceonly explain
set autotrace traceonly statistics
set autotrace traceonly explain statistics

set autotrace off explain
set autotrace off statistics
set autotrace off explain statistics
set autotrace off
set autotrace on
set autotrace traceonly

set autotrace on explain
set autotrace on statistics
set autotrace on explain statistics

set autotrace traceonly explain
set autotrace traceonly statistics
set autotrace traceonly explain statistics

set autotrace off explain
set autotrace off statistics
set autotrace off explain statistics

设置autotrace允许显示DML语句的一些统计信息和/或查询计划。

set autotrace on: 为语句显示统计信息和执行计划。

set autotrace on explain: 只显示执行计划。

set autotrace on statistics: 只显示统计信息。

set autotrace traceonly: 显示执行计划和统计信息，但是打印查询结果。

set autotrace off: 关闭autotrace

如果用statistics选项打开autotrace，那么将显示下面的统计信息：

recursive calls
db block gets
consistent gets
physical reads
redo size
bytes sent via SQL*Net to client
bytes received via SQL*Net from client
SQL*Net roundtrips to/from client
sorts (memory)
sorts (disk)
前置条件

autotrace的执行计划特性需要创建一个plan_table表，可以用脚本

$ORACLE_HOME/rdbms/admin/utlxplan.sql 创建

统计特性需要用户具有v_$sesstat, v_$statname 和 v_$session表上的查询权限。

Oracle安装时附带的$ORACLE_HOME/sqlplus/admin/plustrce.sql 会安装plustrace角色，plustrace角色被授予了这些查询权限。如果plustrace角色被授予用户，那么他就可以具有打开autotrace的权限。或者你也可以把plustrace角色授予public。