oracle数据库CPU过高问题举例分析

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一、环境准备

1、查看当前快照情况

SQL> select max(snap_id) from dba_hist_snapshot s;                                     28

2、手工生成一份快照

exec dbms_workload_repository.create_snapshot;

3、创建实验表

SQL> create sequence s_t3_id minvalue 1 maxvalue 9999999999 start with 1 increment by 1 cache 20 order;SQL> create table t3 (id number,name varchar2(20),created date);Table created.SQL> begin  2  for i in 1 .. 5000000 loop  3  insert into t3 values (s_t3_id.Nextval,dbms_random.string('u', 10),sysdate);  4  end loop;  5  end;  6  /SQL> create sequence s_t4_id minvalue 1 maxvalue 9999999999 start with 1 increment by 1 cache 20 order;SQL> create table t4 (id number,name varchar2(20),created date);Table created.SQL> begin  2  for i in 1 .. 3000000 loop  3  insert into t4 values (s_t4_id.Nextval,dbms_random.string('u', 10),sysdate);  4  end loop;  5  end;  6  /SQL> select * from scott.t3 where name=dbms_random.string('u', 10)；no rows selectedSQL> select * from scott.t4 where name=dbms_random.string('u', 10)；no rows selected

4、手工生成快照

exec dbms_workload_repository.create_snapshot;

至此，模拟问题出现时的快照区间为29-30

二、使用SPA进行分析

begin  2  dbms_sqltune.create_sqlset(  3  sqlset_name=>'cpu_test',  4  description => 'High cpu read tuning set');  5  end;  6  /PL/SQL procedure successfully completed.SQL> declare  2  base_cur dbms_sqltune.sqlset_cursor;  3  begin  4  open base_cur for  5  select value(x) from table(DBMS_SQLTUNE.select_workload_repository(29,30,NULL,NULL,'cpu_time',NULL,NULL,NULL,10)) x;  6  --  7  dbms_sqltune.load_sqlset(sqlset_name=>'cpu_test',populate_cursor => base_cur);  8  end;  9  /PL/SQL procedure successfully completed.SQL> variable sts_task  VARCHAR2(64);SQL> EXEC :sts_task :=DBMS_SQLPA.CREATE_ANALYSIS_TASK(sqlset_name=>'cpu_test',order_by=>'cpu_time',description=>'process workload ordered by cpu_time');PL/SQL procedure successfully completed.SQL> EXEC DBMS_SQLPA.execute_analysis_task(task_name=>:sts_task,execution_params=>dbms_advisor.arglist('TIME_LIMIT','1800'));PL/SQL procedure successfully completed.SQL> set serveroutput onSQL> set heading offSQL> set pagesize 2000SQL> set long 20000SQL> spool compare_report.htmlSQL> select DBMS_SQLPA.report_analysis_task(:sts_task,'HTML','ALL','ALL') from dual;SQL> spool off

查看生产的HTML文件，可看到时间范围内运行的所有sql的信息

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