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关于Partial write for all MySQL and Oracle

Posted by admin on 2nd September 2014

很久之前看过这个帖子,当时没有细究,这几天看了下mysql相关的internal 突然想起这个问题,跟三四个朋友讨论了下 想把这个问题展开讲一讲。

源帖子内容见:https://community.oracle.com/thread/1087650?start=0&tstart=0

这个[……]

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Posted in MYSQL | No Comments »

How to control CF calculation

Posted by admin on 14th May 2013

根据Richard Foote的文章,做了如下验证:

RefClustering Factor Calculation Improvement and provide some control over DBMS_STATS index clustering factor computat[……]

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Active dataguard tips

Posted by admin on 23rd January 2013

11g ADG 给了大家更多的灾备选择,包括之前美国飓风,给了ADG大放光彩的机会,但是ADG并没有想象中的那么完美,以下是最近的一个CASE,具体过程不详写了,目前这个case还在跟进中,记录之:

[oracle@dcb-srv-0174 trace]$ cat itemstd02_ora_[......]

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Capture binds always actually ?

Posted by admin on 28th August 2012

我们可以通过v$sql_bind_capture 捕获到 bind values 这篇文章主要阐述v$sql_bind_capture与v$sql_plan的一些联系

SQL*Plus: Release 11.2.0.3.0 Production on Tue Aug 28 14:07[......]

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some change in cache buffer handle

Posted by admin on 7th June 2012

今天开发因为连接数不够 强烈要求加大processes值,突然想到了processes对_cursor_db_buffers_pinned的影响,,小记之:

当会话需要pin住buffer header时它首先要获去buffer handle,实例所存在的buffer handle总数由(ea[……]

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Oracle latch internals

Posted by admin on 6th June 2012

Oracle latch internals

Server latch implementation called KSL, e.g. every table with name starting with x$ksl... is latch
related and every SGA has ksl... structure as well.  In order to get complete list of x$ksl table,
connect with sysdba permissions to oracle and run query:
 
SELECT kqftanam
FROM x$kqfta
WHERE  kqftanam  LIKE 'X$KSL%'

eg:

[oracle@testdb ~]$ ora si
 
SQL*Plus: Release 11.2.0.3.0 Production on Thu Jun 6 15:37:53 2013
 
Copyright (c) 1982, 2011, OracleAll rights reserved.
 
 
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
 
SQL> SELECT kqftanam
FROM x$kqfta
WHERE  kqftanam  LIKE 'X$KSL%'      2    3  ;
 
KQFTANAM
----------------------------
--
X$KSLLTR

X$KSLHOT
X$KSLLCLASS
X$KSLECLASS
X$KSLEMAP
X$KSLLD
X$KSLED
X$KSLCS
X$KSLSCS
X$KSLES
X$KSLSESHIST
 
KQFTANAM
----------------------------
--
X$KSLEI

X$KSLLW
X$KSLPO
X$KSLWSC
X$KSLWH
X$KSLWT
 
17 rows selected.

There are two structures associated with a latch in KSL – ksl[……]

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Posted in system | 4 Comments »