数据库性能优化解决Oracle数据慢的常见问题

当数据库性能下降时，首先需收集以下步骤1至4的信息，然后根据操作系统情况配合搜集步骤5至9的信息：1、查询数据库等待事件：select count(*), event from v$session_wait group by event；2、查询数据库的锁：SELECT a.OBJECT_ID, a.SESSION_ID, s.SERIAL#, a.ORACLE_USERNAME, OS_USER_NAME, S.PROCESS FROM V$LOCKED_OBJECT a, V$SESSION S WHERE a.SESSION_ID = S.SID；查找数据库锁进程当前执行的SQL：select s.sid, s.serial#, b.spid, s.status, s.username usr, RTRIM(s.osuser) osusr, s.machine, s.program, c.sql_text from v$session s, v$process b, v$sqltext c where s.paddr = b.addr and s.sql_address = c.address and s.sid in (SELECT a.SESSION_ID FROM V$LOCKED_OBJECT a, V$SESSION S WHERE a.SESSION_ID = S.SID) order by s.sid, c.piece。