oracle 11g BaseLine(基线)指定application中不可修改sql的执行计划
11G前有sql profile、outline可以稳定执行计划，但有些文档中指出有时outline指定了但也有要能走新的执行计划，所以11g的BASELINE是OUTLINE的改进版。一般应用在版本升级或稳定特定SQL的执行计划，也可以修改指定SQL的执行计划，当OUTLINE与BASELINE有同时指定时BASELINE有优先权。
weejar zhang
noarchive model,迁tablespace从ASM到Local files fs
利用rman 可以方便的把datafile,tablespace,database在本地文件系统和ASM之间转换
10gGridControl failed to start a managed process after the maximum retry limit
[oracle@dbserver1 bin]$ ./opmnctl startall
failed to start a managed process after the maximum retry limit
[error 13079] [ecid: -] No matching CACHE element found in
sqlserver 游标小例
总忘，小记 declare @c int declare @seq int set @seq=54000101 declare cur cursor for SELECT sectionid FROM StudySection WHERE (yearSemesterID = 2012001) open cur fetch next from cur into @c WHILE @@fetch_status=0 begin set @seq=@seq+1 print @seq update StudySection set oracleid=@seq where sectionid=@c fetch next from cur into @c end close cur deallocate cur
materialized view query rewrite and ORA-30353
启用物化视图的重写有两个条件QUERY_REWRITE_ENABLED=true and materialized view enable query rewrite.
在CBO对查询sql 重写后估算cast后直接查询mv
after OS reboot ,11g RAC asm not automatic startup ORA-27102
[ohasd(4507)]CRS-2807:Resource ‘ora.asm’ failed to start automatically.
SQL> startup nomount
ORA-27102: out of memory
OEL5.8 Install RAC Grid 11203 PRVF-5184 : Check of following Udev attributes failed
PRVF-5184 : Check of following Udev attributes of “rac2:/dev/asm-diskc” failed: “[Owner: Found=’root’ Expected=’grid’, Group: Found=’root’ Expected=’asmadmin’, Permissions: Found=’0600′ Expected=’0660′]”
11gr2 install database加大AMM内存时INS-35171
Oracle Error :: INS-35171
Target database memory (stringMB) exceeds at least one of the selected nodes available shared memory (string MB).
rac 11203 grid 安装PRVF-5636 : The DNS response time for an unreachable node exceeded “15000” ms
OUI默认是带域名的名称如znode1.anbob.com/znode1-vip.anbob.com,去掉改为了znode1/znode1-vip 新增加的znode2/znode2-vip，再下一步到检查的时，检查通过。
Never bind peeking or Wrong execution plan?
注意当用veriable变量绑定时sqlplus autotrace有可能显示的执行计划不是实际的，用dbms_xplan.display_cursor查看
RHEL/OEL 5启用xmanager 远程桌面x
For XDMCP connection to Red Hat 5 EL or CentOS 5 or OEL5
1. Change runlevel to 5
Open /etc/inittab and set the initial runlevel to 5 as following:
id:5:initdefault:
11gr2安装Grid 时 node2 root.sh失败Start of resource “ora.asm -init” failed
Start of resource “ora.asm -init” failed
Failed to start ASM
Failed to start Oracle Clusterware stack
11gr2安装Grid 时 ins-40719 ins-40912
ins-40719 ipaddress configured for single client access name(scan):
rac-scan.anbob.com is already assigned to another system
ORA-00600: internal error code, arguments: [Skgmfail] 案例
数据库在运行一段时间后crash,遭遇ORA-00600: internal error code, arguments: [SKGMFAIL], [2], [4], [4], [1]，重启后又可以正常运行。
Why not use index oracle? 为什么不用索引？ 检查列表
sys_op_descend – Returns value as it would be used in a descending index. This is essentially
reverse() function with output in hex.
rdate 配置时间同步
[root@rac2 ~]# rdate -s 192.168.168.178
RAC那些事，概念
rac 全名Real Application Clusters，是ORACLE DATABASE 上的一个组件， 用共享存储的结构可以把1个数据库运行在多个分别计算的节点instance中 ，来提高了数据库的可用性，可以安装在企业版或标准版中，rac 出生于2001年的9I release 1, 以它的前身是oracle parallel server,rac 引入cache fusion机制提高实例间的资源同步。
Utilities-rlwarp, how to clear history command? do it
RLWRAP_HOME:
directory in which the history and completion files are kept.
RedHat LINUX el 安装UEK内核并安装ORACLE Validated RPM
Oracle为Linux推出了坚不可摧的企业级内核Unbreakable Enterprise Kernel， UEK是一个高速的、新式的、可靠的Linux内核，它们自己的Exadata Database Machine就是基于该内核，也是为oracle自己的软、硬个件优化过的内核
BITMAP CONVERSION FROM/TO ROWIDS
sql就是根据条件一走btree索引把rowid转换为BITMAP,条件二也是走另一个btree索引把rowid转换为另一个BITMAP,然后两个BITMAP 再做and 合并，合并后的结果再转换为ROWID，表再根据rowid取会行记录过滤没有在索引上的其它条件