That’s right… Just completed one month working at USA…
So far, so good… Let’s check if I’ll survive this cold here and of course,
the home sick… 
Tag Archives: enUS
scott/tiger
Almost every Oracle database has had an account called SCOTT with password TIGER. It is named after Bruce Scott (one of the original Oracle employees) and the password is the name of his daughter’s cat. This schema contains the EMP and DEPT tables used in innumerable demos. In recent versions of the database, this account is locked by default and must be unlocked with
SQL> ALTER USER SCOTT ACCOUNT UNLOCK;
Oracle XE inexplicably doesn’t have this classic account, but you can add the user yourself and fill it using the demobld script.
Later versions has an additional demo schema called HR with password HR. This schema contains many additional database objects to allow demonstration of newer database features.
The following links discuss the new sample schemas in more detail.
To drop Scott you need to run the demodrop.sql script
Source: http://wiki.oracle.com/page/scott%2Ftiger
This is one is quick but very helpful
ls -laR | wc -l
With that, you will count all files under the current and subdirectories.
Well, I heard (read to be honest) somewhere that ext4, the evolution of ext3 linux file system, is coming out from development to stable tree (Kernel 2.6.28). However, I was not so sure about the benefits and how this can improve my life and my performance in daily tasks using my 80gb HD laptop. Here is the features I found in my search:
- Large filesystem: It can support volumes with sizes up to 1 exabyte (1024 GB == 1 Tera. 1024 Tera == 1 Peta. 1024 Peta == 1 Exa). Since Linux kernel version 2.6.25, it also supports files as large as the file system.
- Backward and forward compatibility: It has backward compatible with ext3, making it possible to mount an ext3 filesystem as ext4 and vice-versa, but the ext4 to ext3 is only possible if extents is not enabled.
- Delayed allocation: With this feature, ext4 can delay block allocation as long as possible, improving performance and reducing fragmentation, since it will only allocate space with the real file size.
- Expand the subdirectory limit up to 64000: Shame on you Window$
- Faster file system checking: The data structures used in ext4 allows fsck to skip unused blocks of data, which will reduce the time fsck may spend.
- Undelete: It’s not yet implemented but this feature will also be supported and it’s very handy in many situations.
- Other fixes…
But the discussion here: is it really for you ? Do you need a filesystem with 1 exabyte limit ? Create more than 32,000 subdirectories ? I mean, of course that there are other performance improvements and they are very important and welcome, thanks. But I’m not so sure about experiment ext4 now, since I’m only with one machine and using it for work. 
Maybe in few months or with the next Ubuntu release I’ll have it. At least, I’m already aware of what I can expect about ext4.
For those who want’s to migrate from ext3 to ext4 now, I found this step-by-step article at IBM developerWorks and looks very helpful.
Sources:– http://ext4.wiki.kernel.org/index.php/Main_Page
- http://en.wikipedia.org/wiki/Ext4
For those who needs to look at some huge log files (usually generated by Java servers such as weblogic, tomcat or jboss…) or needs to check thread dumps (stuck thread sucks) here goes a great tool: TDA (Thread Dump Analyzer).
In a JEE architecture we have a daily work with multi-thread environments. All applications (or most of them) needs to run in cluster and share the load between many machines, domains, work managers or threads. In such scenarios, it’s important to identify which class made a thread stuck ? What’s going on in the JVM in the moment the application stops working and freeze. In such situations, you can take a look at the thread dump. But what is a thread dump ? In few words: a textual dump of all active threads and monitors of Java apps running in a Virtual Machine.
Of course there are much more to say about thread dumps, but today I’m just posting about a tool that can helps working thread dumps and some server side logs… TDA! (not a sound)
Here are the new features listed from TDA home:
- Tool now is available as VisualVM plugin.
- Skip broken thread dumps.
- Custom Thread Categories.
- New Welcome Screen.
- Small Adjustments to support SAP JVM Dumps (slightly modified from SUN Dumps).
- Small Adjustments to support HP JVM DUmps (slightly modified from SUN Dumps).
