Oracle Knowledge Summary (Part I)
Oracle is a vast system with numerous knowledge points. While studying, whenever I come across some key points, I jot them down. Before I realized it, I had accumulated so much information that I decided to make a small summary. Some of these knowledge points have already been written into individual blog posts (http://blog.csdn.net/tianlesoftware), while others have yet to be organized. As the saying goes, "A good memory is not as reliable as a bad pen," but instead of using a pen, I use digital tools. ^_^ ...
Most of this content was compiled during my time on the CSDN forum. Now, with other commitments, I rarely visit it. The period when I was active on the forums was the time I improved the fastest. Therefore, for those who wish to develop their skills in Oracle, I recommend spending time on forums. When you see topics within your expertise, help others by answering their questions, and if you don't know, take the opportunity to research and learn. Over time, you will see significant improvement and also make many friends. It's truly a win-win situation.
1. A JOB that executes an SQL statement every 5 minutes from 8:00 AM to 11:00 PM daily
-- Create a stored procedure
CREATE OR REPLACE PROCEDURE p_jobtest IS
v_hh VARCHAR...
Published @ May 25, 2010, 11:30:00 | Comments (2) | Edit | Report | Collect
How to Set Up a Database Server Platform
Having worked with Oracle for two years now, I have never stopped learning. There is so much to learn, and even now, after starting out, I still feel the same way. Sometimes, I wonder how long it will take before I feel confident about my abilities. Many friends want to become DBAs because they perceive it as a high-paying industry. However, not everyone understands why DBAs are highly compensated. High pay means high pressure and great responsibility. The more modernized a system is, the greater its reliance on databases becomes. Consequently, data security and system security become increasingly important. For example, in a company's business system, the database is the direct storage location, and its importance cannot be overstated. Downtime can result in losses calculated per minute or even per second, and who is responsible for these databases? - The DBA. Therefore, many companies seek experienced DBAs to ensure the reliability of their systems. This is also why enterprises are hesitant to hire DBAs without practical experience to manage their databases. Imagine if a provincial mobile database encountered issues, leading to data loss, or if a bank's database went down. The resulting losses would not only disrupt normal business operations but could also lead to data errors. For instance, if you deposited 1 million yuan in a bank, and due to a mistake in the database, several zeros were missing. This is something no one wants to see. ...
Published @ May 17, 2010, 23:16:00 | Comments (5) | Edit | Report | Collect
Web Stress Testing Tool -- WebBench
Webbench is a website stress testing tool for Linux that can simulate up to 30,000 concurrent connections to test a website's load capacity. It was developed by Lionbridge.
Previously, I organized an introduction to the Apache AB testing tool, which you can find in my Blog:
Web Stress Testing Tool -- Apache AB
http://blog.csdn.net/tianlesoftware/archive/2010/11/23/6028577.aspx
Webbech can test the performance of different services on the same hardware or the same service on different hardware. Standard tests with Webbench can show us two aspects of server performance: the number of requests responded to per second and the amount of data transmitted per second.
Webbench not only has the ability to test standard static pages but also dynamic pages (ASP, PHP, J***A, CGI). Additionally, it supports static or dynamic performance testing for secure websites with SSL, such as e-commerce sites.
Published @ November 23, 2010, 12:36:00 | Comments (0) | Edit | Report | Collect
Web Stress Testing Tool -- Apache AB
AB (ApacheBench) is a HyperText Transfer Protocol (HTTP) performance testing tool that comes with Apache. Its design purpose is to depict the execution performance of the currently installed Apache, mainly showing how many requests Apache can handle per second.
This tool is included with Apache. After installing Apache Http Server, you will have access to the ap program. You can download Apache Server directly from the Apache official website:
http://httpd.apache.org/download.cgi#apache22
After installation, the ab.exe program will be located in the Bin directory of Apache. This is our AB tool.
Usage method for AB tool:
C: >cd C:\Program Files (x86)\Apache Software Foundation\Apache2.2\bin
C:\Program Files (x86)\Apache Software Foundation\Apache2. ...
Published @ November 23, 2010, 00:41:00 | Comments (1) | Edit | Report | Collect
RAC Connection Redirected To Wrong Host-IP ORA-12545 [ID 364855.1]
Modified 16-APR-2010 Type PROBLEM Status PUBLISHED
In this Document
Symptoms
Cause
Solution
References
Applies to:
Oracle Net Services - Version: 9.2.0.8.0 to 11.1.0.7.0 - Release: 9.2 to 11.1
Information in this document applies to any platform.
Checked for relevance on 9-APR-2010. Symptoms
When we try to connect to a RAC service name, we...
Published @ November 22, 2010, 17:13:00 | Comments (0) | Edit | Report | Collect
Let the Years Turn Gray
On a night in my senior year of high school at 12 o'clock, I listened to Wang Xi telling stories on Anhui Music Radio. That day, the story was about the novel: "Let the Years Turn Gray." Many years have passed, and I still remember the situation back then...
The background music of the story was very moving, it was the Scottish bagpipe, "the level plain." At the end of the story, Chen Sheng's "Leave the Sadness for Yourself" was played. Part of the recording is available online, but it's incomplete, and my own recordings were even less clear. Back then, I recorded it using a tape recorder.
Later, I heard that the program time was reduced from 2 hours, to 1.5 hours, to 1 hour, and finally canceled...
The novel follows:
One
During my fourth year of college in the first semester, the courses were no longer heavy. Like all seniors, I lived a carefree life. I spent all my free time reviewing Jin Yong, Gu Long, and Wen Rui'an novels. Lying in bed or on the grass, I wandered in my thoughts, thinking that such days could last for three hundred years. Until one day, the peaceful days came to an abrupt end, and in the following years...
Published @ November 22, 2010, 13:50:00 | Comments (0) | Edit | Report | Collect
Functions of Various Folders in Linux
1. Linux Directory Structure
Under normal circumstances, the root file system should occupy relatively little space since most files do not need frequent changes, and including strict files and a small infrequently changing file system makes it less prone to damage.
Except possibly for a standard system boot image called /vmlinuz, the root directory generally contains no files. All other files are in subdirectories of the root file system.
Under the root directory in Linux, there are the following directories:
[root@racnode1 /]# ll
drwxr-xr-x 2 root root 4096 10-28 21:22 bin
drwxr-xr-x 4 root root 1024 11-10 23:17 boot
drwxr-xr-x 15 root root 5120 11-12 22:24 dev
drwxr-xr-x 100 root root 12288 11-13 16:17 etc
drwxr-xr-x ...
Published @ November 19, 2010, 16:39:00 | Comments (0) | Edit | Report | Collect
ORA-16032 Can not Start Instance via srvctl but via sqlplus is fine [ID 1062071.1]
Modified 07-OCT-2010 Type PROBLEM Status PUBLISHED
In this Document
Symptoms
Changes
Cause
Solution
Applies to:
Oracle Server - Enterprise Edition - Version: 10.1.0.2 to 11.2.0.1 - Release: 10.1 to 11.2
Information in this document applies to any platform.Symptoms
Using 11.2 Grid Infrastructure, the database instances cannot be...
Published @ November 19, 2010, 00:15:00 | Comments (0) | Edit | Report | Collect
Oracle RAC CRS-0184 -- Cannot Communicate with the CRS Daemon
After installing Oracle 11gR2 RAC and starting CRS, the following error occurred:
[root@rac1 bin]# ./crsctl check crs
CRS-4638: Oracle High Availability Services is online
CRS-4535: Cannot communicate with Cluster Ready Services
CRS-4529: Cluster Synchronization Services is online
CRS-4533: Event Manager is online
From this error message, it can be seen that CRS failed to start. CRS is a critical process. If it fails, the Clusterware will also fail to start. There are many reasons for this issue.
Log as follows:
[root@rac1 rac1]# tail -50 /u01/app/11.2.0/grid/log/rac1/crsd/crsd.log
ORA...
Published @ November 18, 2010, 17:10:00 | Comments (0) | Edit | Report | Collect
Explanation of "Private Strand Flush Not Complete"
A few days ago, a friend asked me a question. She said she saw the following information in the alert log:
Thread 1 cannot allocate new log, sequence 415
Private strand flush not complete
Current log# 4 seq# 414 mem# 0: /dev/rora_redotb04
Thread 1 advanced to log sequence 415
Current log# 5 seq# 415 mem# 0: /dev/rora_redotb05
Thu Nov 11 16:01:51 2010
I encountered "Checkpoint not complete." For explanations regarding this, refer to my Blog:
Redo Log and Checkpoint not complete
ht...
Published @ November 17, 2010, 17:39:00 | Comments (0) | Edit | Report | Collect
Oracle Redo Parallel Mechanism
Redo log is used for recovery and an advanced feature, containing all the information about the changes caused by corresponding operations. All redo entries eventually need to be written into the redo files. The Redo log buffer is a block of memory allocated in the SGA to avoid performance bottlenecks caused by Redo file IO. A redo entry is first generated in user memory (PGA), then copied to the log buffer by the Oracle server process, and subsequently written to the redo file by the LGWR process when certain conditions are met.
Since the log buffer is a "shared" memory area, it is protected by the redo allocation latch to avoid conflicts. Each server process must acquire this latch before allocating the redo buffer. Therefore, in high-concurrency OLTP systems with frequent data modifications, we often observe waits for the redo allocation latch. The entire process of writing redo entries to the redo buffer is as follows:
Generate Redo Entry in PGA -> Server Process Acquires Redo Copy Latch -> Write Redo Entry to Redo Buffer...
Published @ November 17, 2010, 15:05:00 | Comments (0) | Edit | Report | Collect
Solution for Oracle 11gR2 RAC ORA-00845 MEMORY_TARGET not supported on this system
Our company recently launched a set of Oracle 11gR2 RAC. After setting the MEMORY_TARGET memory to 12G, an error occurred during startup:
ORA-00845: MEMORY_TARGET not supported on this system
00845, 00000, "MEMORY_TARGET not supported on this system"
// *Cause: The MEMORY_TARGET parameter was not supported on this operating system or /dev/shm was not sized correctly on Linux.
// *Action: Refer to documentation for a list of supported operating systems. Or, size /dev/shm to be at least the SGA_MAX_SIZE on each Oracle instance...