Maclean’s Oracle Database Tech Blog Archives

以下罗列一些Oracle中的Top-N与分页匹配查询优化写法： CREATE INDEX i_pop ON cities(population); TOP-N SELECT * FROM ( SELECT name, population FROM cities ORDER BY population DESC ) WHERE rownum

oracle 11g r2 on windows platform released today , we can test it now.

升级到FF3.6的朋友肯定发现了现在使用火狐浏览器访问my oracle support 时许多页面打开为空白页，譬如这篇介绍FF3.6与目前oracle support site兼容性的文章： Firefox 3.6 Not Officially Supported by My Oracle Support Although much of the functionality of My Oracle Support is accessible via Firefox 3.6, please be aware that Firefox 3.6 is not officially supported by My Oracle Support at this time. Please review the My Oracle Support FAQ (Knowledge Document…

The status of buffer locks can be checked through the table X$KJBL; it is not necessary to dump the locks with the ORADEBUG command, in order to get to this information. The table contains the client and shadow locks.     Column name            Data type            Description KJBLLOCKP              RAW,kjbl*            Lock pointer. Can be joined with X$LE.LE_KJBL.…

X$KJMSDP The table X$KJMSDP has entries for each LMS process that is configured for the instance. The default number of LMS processes is the number of CPU’s divided by 4, but 2 as a minimum. The LMS processes are responsible for the delivery of the GCS messages and blocks to the other instances.    …

有网友反映在11.2的RAC中有一个名如*_preconnect.svc的资源一直处于OFFLINE状态，而其TARGET则为ONLINE状态，无法通过重启CRS或者手动start该资源来使之ONLINE。我们来具体看一下什么情况下回产生这种资源?: [oracle@rh2 ~]$ srvctl add service -h Adds a service configuration to the Oracle Clusterware. Usage: srvctl add service -d -s {-r “” [-a “”] [-P {BASIC | NONE | PRECONNECT}] | -g [-c {UNIFORM | SINGLETON}] } [-k ] [-l [PRIMARY][,PHYSICAL_STANDBY] [,LOGICAL_STANDBY][,SNAPSHOT_STANDBY]] [-y {AUTOMATIC | MANUAL}] [-q {TRUE|FALSE}] [-x {TRUE|FALSE}] [-j {SHORT|LONG}] [-B {NONE|SERVICE_TIME|THROUGHPUT}]…

  [gview file=”https://www.askmac.cn/wp-content/uploads/2010/03/Diff-Hidden-Parameter-between-10g-and-11g.pdf”]

运行在操作系统上的进程存在2种系统时序优先级模式:即 实时模式 Real Time(RT) mode, 与分时模式 Time Sharing(TS) mode. 绝大多数Oracle进程运行在TS模式下： [oracle@rh1 ~]$ ps -efc|grep ora_|grep -v grep oracle 8510 1 TS 23 Mar27 ? 00:00:02 ora_pmon_PROD oracle 8512 1 TS 23 Mar27 ? 00:00:00 ora_psp0_PROD oracle 8514 1 TS 23 Mar27 ? 00:00:00 ora_mman_PROD oracle 8516 1 TS 23 Mar27 ? 00:00:02 ora_dbw0_PROD oracle 8518…

1. Goal and mission: A System Engineer has excellent and in-depth knowledge of a family of products (e.g. NagraVision CAS, iDTV & SMS, MediaGuard CAS). He is the recognised expert on that range of systems and is able to analyse and resolve complex problems under severe pressure. He recognises the importance of excellent customer relationships…

今天没有外出(似乎人不到现场就特别容易出问题),早上10点左右接到电话被告知crm11实例上出现了7445错误，准备用web vpn拨上去查看一下，赫然发觉windows 7 不支持这种vpn(准确说ie8和firefox都不支持)；无奈无奈只好用拨号。 发现alert log中出现大量 7445错误记录： Fri Mar 26 09:24:53 2010 Errors in file /oravl01/oracle/admin/CRMDB1/udump/crmdb11_ora_6754320.trc: ORA-07445: exception encountered: core dump [kghalp+0500] [SIGSEGV] [Invalid permissions for mapped object] [0x00000003B] [] [] Fri Mar 26 09:24:55 2010 Trace dumping is performing id=[cdmp_20100326092455] Fri Mar 26 09:31:16 2010 Errors in file /oravl01/oracle/admin/CRMDB1/udump/crmdb11_ora_2994552.trc: ORA-07445: exception encountered: core dump…