ANBOB

In earlier releases of Oracle Database, the MAXTRANS parameter limited the number of transaction entries that could concurrently use data in a data block. This parameter has been deprecated.

今天无意执行了一个脚本，后来发现kill 了j000和m000的进程，oracle被僵死在那里，j000是job的守护进程，m000是MMON进程启动的从属平行进程，都是轻量级但不容忽视！

总体就是说Oracle Outline是用来保持SQL执行计划（execution plan）的一个工具。我们可以保存一个时间点的执行计划，用于数据改变或系统环境改变而限制cbo,rbo强行执行原保存的执行计划，注意的是，这个执行计划现在适用随着数据的变化明天不一定是最好的。

今天 在一个oracle高级调优的例子，提到Cluster_Factor的概念，觉的很有意思，在这分享一下,CLUSTER_FACTOR对Oracle执行计划会产生重要影响。这个值越高，说明索引的使用效率将会越差….

system@ORCL> create table testnull(id int not null,name varchar2(10) not null);

Table created.

SQL> startup mount
ORA-32004: obsolete and/or deprecated parameter(s) specified
ORACLE instance started.

alter database mount
*
ERROR at line 1:
ORA-00201: control file version 10.2.0.3.0 incompatible with ORACLE version 10.2.0.1.0

Connected.
ERROR:
ORA-01012: not logged on

昨天开发的让我从生产库中同步一个库到测试机，刚好手头有这周一的exp备份，imp了一份，但是今天早上开发打电话找我说情况有点不对头，同一个SQL在生产库上与测试库的执行时间差很多，测试库2秒，生产库要1分钟多 …

A TX lock is acquired when a transaction initiates its first change and is held until the transaction does a COMMIT or ROLLBACK. It is used mainly as a queuing mechanism so that other sessions can wait for the transaction to complete. The lock name (ID1 and ID2) of the TX lock reflect the transaction ID of the active transaction.

ERROR at line 1:
ORA-04068: existing state of packages has been discarded
ORA-04065: not executed, altered or dropped stored procedure “ANBOB.P_INSERT”

SQL> alter database default tablespace test;

Database altered.

EXP-00008: 遇到 ORACLE 错误 904
ORA-00904: “MAXSIZE”: invalid identifier

今天 有人提起了这个异常，未能将审计记录写入Windows 事件日志，这是WINDOWS平台的一个通病，如果开启了审计，如果应用软件再有频繁操作，一会儿功夫可能就会写满日志最大容量。

sys@ORCL> DESC DBA_ROLLBACK_SEGS;
SP2-0749: Cannot resolve circular path of synonym “DBA_ROLLBACK_SEGS”