1、初始化参数
1）STATISTICS_LEVEL（Dynamic: ALTER SESSION, ALTER SYSTEM）
BASIC: No advisories or statistics are collected.
TYPICAL: The following advisories or statistics are collected:
Buffer cache advisory
MTTR advisory
Shared Pool sizing advisory
Segment level statistics
PGA target advisory
Timed statistics
ALL: All of the preceding advisories or statistics are collected, plus the following:
Timed operating system statistics
Row source execution statistics
2）TIMED_STATISTICS（Dynamic: ALTER SESSION, ALTER SYSTEM）
如果STATISTICS_LEVEL设置为basic，要收集统计信息，TIMED_STATISTICS必须设为true
3）SQL_TRACE（Static，alter session）
2、打开sql trace
alter session set sql_trace=true;
将在udump目录下生成trace文件
3、将trace文件格式化成报告
$ tkprof orasafe_ora_24082.trc out.rpt sort=prscpu
4、报告注解
PARSE ：Translates the SQL statement into an execution plan, including checks for proper security authorization and checks for the existence of tables, columns, and other referenced objects.
EXECUTE： Actual execution of the statement by Oracle. For INSERT,UPDATE, and DELETE statements, this modifies the data. For SELECT statements, this identifies the selected rows.
FETCH： Retrieves rows returned by a query. Fetches are only performed for SELECT statements.
COUNT： Number of times a statement was parsed, executed, or fetched.
CPU： Total CPU time in seconds for all parse, execute, or fetch calls for the statement. This value is zero (0) if TIMED_STATISTICS is not turned on.
ELAPSED： Total elapsed time in seconds for all parse, execute, or fetch calls for the statement. This value is zero (0) if TIMED_STATISTICS is not turned on.
DISK： Total number of data blocks physically read from the datafiles on disk for all parse, execute, or fetch calls.
QUERY： Total number of buffers retrieved in consistent mode for all parse, execute, or fetch calls. Usually, buffers are retrieved in consistent mode for queries.
CURRENT： Total number of buffers retrieved in current mode. Buffers are retrieved in current mode for statements such as INSERT,UPDATE, and DELETE.
ROWS： Total number of rows processed by the SQL statement. This total does not include rows processed by subqueries of the SQL statement.