https://db-blog.web.cern.ch/blog/luca-canali/2014-12-life-oracle-io-tracing-logical-and-physical-io-systemtap Luca Canali on 01 Dec 2014 Topic: This post is about tracing logical and physical reads in Oracle using SystemTap. You find here a few examp…

开启dblink的 oracle net trace/tracing --对dblink进行跟踪的方法. 參考原文: DBLINK: How to Enable Oracle Net Tracing for Database links (Doc ID 746917.1) 适用于: Oracle Net Services - Version 9.2.0.1.0 to 11.2.0.3 [Release 9.2 to 11.2] Information in this document appli…

Logical vs physical address  1) An address generated by the CPU is a logical address. Whereas, an address seen by the memory unit, that is, the one loaded into the memory-address register of the memory, is a physical address. 2) The user program neve…

Oracle的DATAGUARD环境,有PHYSICAL STANDBY和LOGICAL STANDBY两种.PHYSICAL STANDBY是传输REDO传到Standby端,然后由Standby端的MRP进程应用该Redo,以达到同期效果.LOGICAL STANDBY是传输REDO传到Standby端,然后由Standby端的LSP进程调用LogMiner来抽取SQL文,然后执行该SQL文以达到同期效果.这里介绍一个简单的确认同期状况的方法: ODM TEST CASE==========…

在查询性能优化时,Logical Read非常重要,它的计数一般与查询出来的结果集数量成正比,与数据读取的速度也成正比. 1,SET STATISTICS IO 显式Disk IO的信息 Syntax SET STATISTICS IO { ON | OFF } Output item                           Meaning             Table Name of the table. Scan count Number of scans performe…

Luca Canali on 26 May 2016 Topic: In this post you will find a short discussion and pointers to the code of a few sample scripts that I have written using Linux BPF/bcc and uprobes for Oracle tracing. Previous work and motivations Tools for dynamic t…

Luca Canali on 28 Jul 2015 Topic: this post is about some simple tools and techniques that can be used to drill down high-latency I/O events using SystemTap probes. The problem: Operations with high latency on a filesystem and/or a storage volume can…

Luca Canali on 21 Jan 2016 Topic: this post is about Linux perf and uprobes for tracing and profiling Oracle workloads for advanced troubleshooting. Context The recent progress and maturity of some of the Linux dynamic tracing tools has raised intere…

  Definitions A trace file is a file that contains diagnostic data used to investigate problems. Also, trace files can provide guidance for tuning applications or an instance.   Types of Trace Files Each server and background process can periodically…

最近一直想用sql来生成oracle的健康检查报告,这样看起来一目了然,经过网上搜资料加自己整理终于算是成型了,部分结果如下图所示, 具体参考附件,恳请广大网友看看是否还有需要添加的地方. DB_healthcheck_by_lhr_ORADG11G_20150826160539.zip ORADG11G 数据库巡检报告 Copyright (c) 2015-2100 (http://blog.itpub.net/26736162) lhrbest. All rights reserved. 巡…