Last year, I spent some time researching redo log related performance problems, which resulted in a mini-series, including one post devoted specifically to one previously unknown scenario of excessive log file sync waits.
I am happy to announce that a service request opened on the back of this research resulted in the MOS note on “log file parallel write” wait event (Doc ID 34583.1) having been updated with a general description of this scenario (more...)
Travel time is writing time and I have the perfect setting for a techie post. Actually I got quite excited about the subject causing the article to get a bit longer than initially anticipated. In this part you can read about block cleanouts when using buffered I/O. The next part will show how this works using direct path reads and Smart Scans.
The article ultimately aims at describing the enhancements Exadata brings to the table (more...)
In just under a month I’ll be off to Dublin for the 2015 OUG Ireland conference. It takes place on Thursday the 19th of March. I’m doing my favorite presentation to present, on I.T. disasters I have witnessed and what you can learn from them (so now the title of this blog makes sense and maybe is not as exciting as it suggested).
I used to do this talk once or twice a year (more...)
Two posts from me on the same day. The other one about Datapatch is about a brand new utility in 12c and is probably new to most people. This post caused mixed reactions when I mentioned it at work last week. Some people laughed at my naivety in not knowing about it, others took the same view as me and were interested to hear about it as it may prove useful one day.
A colleague (more...)
There have been a few changes in the way patches are managed and monitored in 12c and whilst looking at this I found a potential problem that might occur when you clone or copy databases around, or even build them from a template file.
Firstly when you apply a PSU and run an opatch lsinventory command you now see a description of the patch rather than just a patch number – here showing that PSU (more...)
Yet again, it was a fantastic time at the RMOUG Training Days 2015 conference, as it has been every other year I have attended it. That is in no small measure due to the incredible work of the organizing committee, and in particular the Training Days Director, my colleague Kellyn Pot’Vin Gorman of dbakevlar.com fame. For me personally, the travel to get to Denver Colorado was somewhat more daunting than in previous years (see (more...)
Here is a link (Final version presentation and supporting files ) to zip file containing the final version of the presentation as well the script and sql file shown at the end of the presentation. Please let me know if (more...)
If you are running Oracle EE, there are many books on Data Guard. However, for Oracle SE and manual standby, have fun searching.
I wanted to get a better understanding of registering logfile.
Depending on how the standby environment is monitored, not registering logfile may yield incorrect results when checking standby lag.
When logfile is not registered, v$archived_log is not updated.
STANDBY: check status
[oracle@armor:hawk:/home/oracle] $ sqlplus / as sysdba @stby.sql SQL*Plus: Release 11. (more...)
With Data Guard, you have the choice between Physical and Logical Standby databases. Let’s see the differences! My demo starts with a Physical Standby, that is then converted into a Logical Standby (therefore the name of the database):
[oracle@uhesse1 ~]$ dgmgrl sys/oracle@prima DGMGRL for Linux: Version 18.104.22.168.0 - 64bit Production Copyright (c) 2000, 2009, Oracle. All rights reserved. Welcome to DGMGRL, type "help" for information. Connected. DGMGRL> show configuration; Configuration - (more...)
This is the fourth article of a series that focuses on database security. In my introduction, I provide an overview of the database protection process and what is to be discussed in future installments. In last month’s article, we finished our discussion of the most common threats and vulnerabilities. In this latest installment, we’ll review the database vulnerability assessment process. We’ll begin by learning how to perform an initial database vulnerability (more...)
There are a few user group meetings coming up in the UK over the next week or two.
Note, you need to register to attend any of these, follow the links.
First is Club Oracle London, which are evening sessions held in London with 3 talks plus free beer and pizza. The next meeting is Thursday Feb 26th at 103a Oxford Street, kicking off at 18:30. You can register for this free event here and (more...)
2. Hybrid Distribution For Skewed Join ExpressionsThe HYBRID HASH distribution allows to some degree addressing data distribution skew in case of HASH distributions, which I've described in detail already in the past. A summary post that links to all other relevant articles regarding Parallel Execution Skew can be found here (more...)
This is a small article telling how to move a innoDB table from one MySQL server to another.
Moving MyISAM table from one server to another is very straight forward process. MyISAM table generates 3 files at file system level.
- .frm file contains table structure/definition
- .MYD file contains table data
- .MYI file contains index data
We can simply copy these 3 files to another MySQL server installation under desired database and it will show up (more...)
I noticed the error message when running lsinventory against a 22.214.171.124 Oracle_Home. As the command worked I didn’t think anymore of it until on the same server against an 126.96.36.199 home I got the same error message.
opatch lsinventory tr: extra operand `y' Try `tr --help' for more information. /app/oracle/product/188.8.131.52/dbhome_1/OPatch/opatch: line 384: [: =: unary operator expected
There is a Mos note which provides a solution (more...)