这几天在摆弄Oracle9，昨天莫名其妙出了个问题，大概是在执行catexp.sql之类的脚本的时候出现的。
ora-04020:deadlock detected while trying to lock object
sys.cdc_alter_ctable_before
查了一下，居然是个Bug，又中奖了~
Bug 3017048 - Ora-4020, Functional Index Locking During Invalidation Causing Self-Deadlock
Applies to:
Oracle Server - Enterprise Edition - Version: 9.2.0.7.0
This problem can occur on any platform.
解决办法，可以在命令行下修改3个参数的值，
alter system set "_system_trig_enabled"=false
alter system set "aq_tm_processes"=0
alter system set "job_queue_processes"=0