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Dynamic server tracing allows for tracing at a per-process level and can be enabled ad hoc on any running server process. This is useful for tracing individual server side processes of a specific client connection or for tracing background server processes.
上周也就是2013年的最后一天，突然客户反应有些WEB应用页面报错只提到了ora-28002, 我立即用sqlplus 登录提示是ora-28001,显然密码已经过期, 我清清楚记的才因为一起类似问题, 前不久把所有的oracle 数据库应用用户profile PASSWORD_LIFE_TIME改为unlimited，怎么还会这样呢?
Large objects (LOBs) are not supported in comparison conditions. However, you can use PL/SQL programs for comparisons on CLOB data.
skgpspawn failed:category = 27143, depinfo = 24, op = pipe, loc = skgpspawn2
…
oracle 12c release 1版本引入新功能可隐藏列(invisible columns),这个特性有很多的争议，不明白为什么ORACLE会推出这个特性，因为这个特性可能会带来很多麻烦..
今天开发的同事找我说是一个报表系统的SQL执行第一次很快，再执行就慢的几乎查询无响应，找他要来了SQL，也是常见的表关连LIFT JOIN 、GROUP BY的统计报表, 出于篇幅原因不再贴SQL， 把SQL放到TOAD 中问题依然可以再现，..
Adaptive Log File sync was introduced in 11.2. the feature is exactly enabled since release 11.2.0.3 , It’s enabled through an underscore parameter called _use_adaptive_log_file_sync and the description of this parameter is: adaptively switch between post/wait and polling. Oracle can switches between the 2 methods: Post/wait, traditional method for posting completion of writes to redo … Read more
Sometimes we need to enable sql*net trace to diagnose sqlplus connection problems such as ora-125*
Below are the steps to configure Sql*Net verbose Client side tracing:
Each time your program performs a function call, information about the call is generated. That information includes the location of the call in your program, the arguments of the call, and the local variables ..
This script displays the top 50 longest idle times and list distribution of sessions on the instance..
高parse calls表示这些SQL不可以re-used 并且每次执行都要重新解析，理想的最佳状态是一次解析多次执行，你也知道频繁的解析会给library cache带来沉重的负担， 一个sql的执行必须先parse，解析过程包含sql 加载到shared pool, 语法检查…
When multiple connection created will insert a lot of rows in aud$ table, there may be contention in the segment header for the table. This contention can manifest itself as a buffer busy wait or a freelist wait.
alter system set memory_max_target=0 scope=spfile;
shutdown immediate
startup
SQL> show parameter target
…
memory_max_target big integer 3824M
Exception [type: SIGSEGV, Address not mapped to object] [ADDR:0x10] [PC:0x938E8C5, dbgtrReserveSpace()+99] [flags: 0x0, count: 1]
Errors in file /oracle/diag/rdbms/ora11g/ora11g/trace/ora11g_ora_13864.trc (incident=60801):
ORA-07445: exception encountered: core dump [dbgtrReserveSpace()+99] [SIGSEGV] [ADDR:0x10] [PC:0x938E8C5] [Address not mapped to object] []
Incident details in: /oracle/diag/rdbms/ora11g/ora11g/incident/incdir_60801/ora11g_ora_13864_i60801.trc
Use ADRCI or Support Workbench to package the incident.
scn(system change number) 结构主要维护 oracle数据库内部的数据一致性，SCN 有两部分组成: Base and wrap，wrap 是16bit的数字，base是32bit的数字,这样其实就可以算scn的有效范围，它的格式(redo dump trace)是wrap.base，当base超过了2的32次方,然后wrap 就会加1，其实用sql 很好验证。
Why SQL Test Case Builder? For most SQL problems, the single most important factor for a speedy bug resolution is to obtain a reproducible test case. However, this is normally the longest and most painful step for customers. The goal of the SQL Test Case Builder (TCB) is to automatically gather as much information as … Read more
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
DDE: Problem Key ‘ORA 312’ was flood controlled (0x5) (no incident)
ORA-00312: online log 2 thread 1: ‘/oracle/oradata/icme/redo02.log’
Error 19527 creating/clearing online redo logfile 2
ORA-24247: network access denied by access control list (ACL)
ORA-06512: at “SYS.UTL_TCP”, line 17
ORA-06512: at “SYS.UTL_TCP”, line 267
DEMO 1,How to use oradebug to call OS commands via the database
DEMO 2,Disable sys audit
ORA-39083: Object type JOB failed to create with error:
ORA-00001: unique constraint (SYS.I_JOB_JOB) violated