Using HQL Console for JPA facet in Intellij

You got a complicated HQL or JPAQL in your code that has some problems, you need to verify what exactly the query is doing, how should you go ahead to test run it in your database? One option is that you can read the HQL or JPAQL and manually translate it to SQL statement and run the sql statement in your Database, however, this method is error prone and tedious. Another option is use the HQL Console came with Intellij, I found this method is easy and more accurate comparing to the previous options. Here is how I did it:

• Create a DataSource in Intellij, let's name it datasource_1
• Go to the Project->View:J2EE structure->right click the module your pojos are located in, edit the JPA facet properties to set datasource_1 maps to the desired Persistent Unit, and set the default JPA provider to: Hibernate.
• Project->View:J2EE structure->right click the Persistent Unit, you should be able to start HQL Console.
  
• You can paste your HQL or JPAQL in the HQL Console and try it out, or you can generate SQL for it and run the SQL in your DB.

Update: In Intellj 9, there is a little bit change where you can find the Persistent Unit to start HQL Console, you should click the Persistence tab on the left corner of Intellij 9.

Unable to access jarfile on Cygwin

Today I ran into a strange problem on Cygwin: I give the full path to the jar file for the java command, but strangely, the java runtime shows me the error message: Unable to access jarfile /cygdrive/c/pathtojar/.yuicompressor.jar. What is going on? did I have a typo? No. Then Why? After scratch my head enough, I figure out that the java in Cygwin does not like Unix format path to specify the jar file. You can use cygpath to do the trick to convert the Unix format path to mixed(-m) or windows format(-w) path, the java command will happily take it and use the jar file. Here are the two commands that works for me:

• java -jar `cygpath -m /cygdrive/c/pathtojar/.yuicompressor.jar`
• java -jar `cygpath -w /cygdrive/c/pathtojar/.yuicompressor.jar`
  

pip install python packages makes it easy

pip is easy_install replacement, and it is easy to use. Here are some features I recently used:

1. To install something from Python Package Index, for example, Django 1.1, you just issue: pip install django, it will download it and install it.
2. To see what Python Packages were installed by pip, you can use command: pip freeze, of course, you can redirect the output to a file and pass around.
3. To uninstall a Python Package, for example, Django 1.1 installed in step 1, the command is: pip uninstall django.
4. To install some Python Package you may run into error: No distributions at all found for xxxxx, you can supply the package file url to the pip install command, for example, if you want to install Django 0.96.5, here is the command: pip install http://www.djangoproject.com/download/0.96.5/tarball/, this one is pretty cool, if you can find the package gz file, then you can install it by using pip.
   

Install MySQL-python on Cygwin

After pulling my hairs and scavenging the Google, finally I succeeded installed the MySQL-python on Cygwin.

• Build MySQL on Cygwin

• Download MySQL source package from here. I was using mysql-5.0.76.tar.gz
• configure && make && make install

• Install MySQL-python on Cygwin
• Download MySQL-python . I was using 1.2.2. Unzip it.
• ./setup.py install, if you run into any problem, please have look on the readme file of the MySQL-python package. You may need to update threadSafe=False in the site.cfg file.
  

PIL error: IOError: decoder jpeg not available

After installing PIL on Cygwin, I ran into the following error while I am trying to load data from a JPEG file.
IOError: decoder jpeg not available
To solve this problem I did the following steps:
Remove the installed PIL from Cygwin:
rm -rf /usr/lib/python2.5/site-packages/PIL
rm /usr/lib/python2.5/site-packages/PIL.pth

Install libjpeg by using Cygwin setup.exe

Rerun PIL setup.py install.

unable to remap C:\cygwin\bin\tk84.dll

While installing PIL(Python Imaging Libary) on Cygwin, I ran into the following error:
5 [main] python 4388 C:\cygwin\bin\python.exe: *** fatal error - unable to remap C:\cygwin\bin\tk84.dll to same address as parent(0x410000) != 0
x700000
22 [main] python 4636 fork: child 4388 - died waiting for dll loading, errno 11
error: Resource temporarily unavailable

Fortunately, with the help of Google, it is easy to find an existing solution from Datahammer's blog:
c:\cygwin\bin\ash
cd /bin
./rebase -b 0x100000000 tk84.dll

Rerun the PIL setup.py install in Cygwin shell.

Update: If you run into remap error on Cygwin, you could try rebaseall
c:\cygwin\bin\ash
cd /bin
./rebaseall

Unix commands help on diagnosing Weblogic problems

While working on diagnosing the Weblogic problems, I found the unix commands help me a lot, here they are:

• Apache error_log files BackEnd errors: grep -r -h --include=error_log Backend . | awk '{print $2 " " $3}'| sort | uniq -c
  
  
• Oracle connections: while true; do netstat -an|grep 1521; netstat -an|grep 1521|wc -l; echo "+++++++++++++++++++"; sleep 4; done;