Installing Oracle XE on Ubuntu

Oracle XE is available for 32-bit architecture (i386) Linux only, although it may be possible to force installation on a 64-bit host. It will run in 512KB RAM but requires a 1GB swap space. Add:

deb http://oss.oracle.com/debian unstable main non-free

to /etc/apt/sources.list and then as root: 

wget http://oss.oracle.com/el4/RPM-GPG-KEY-oracle  -O- | sudo apt-key add - 
apt-get update
apt-get install oracle-xe

‘libaio’ and ‘bc’ are in the repository, so dependencies will pull them in if the user doesn’t have them.

Incanto

After months of delay I’ve finally switched all my database creation scripts to Incanto. The most obvious benefit is that my Ant build scripts are now more portable, as I am no longer exec’ing a shell script wrapper to sqlplus, and I no longer need Cygwin to run the build scripts on my Windows workstation. One of the nice features about Incanto is that it allows you to pass in an Ant propertyset which is used to define SQL*Plus variables for the invoked scripts. I find this useful for overriding schema names and allowing multiple sets of application schemas to be created in the same developer database, for example when researching support issues alongside new development. The Incanto website has a page of best practices including a <macrodef> which I placed in a shared build file and <import>ed into my various Ant scripts.

Incanto requires sqlplus to be on the PATH, so I handle that and setting login parameters in .antrc. One strange issue I encountered on SLES while making this transition was that even although sqlplus was on my PATH and executable from my shell scripts, when I used Incanto I got

java.io.IOException: java.io.IOException: sqlplus: not found

Changing the permissions on sqlplus from 750 to 755 resolved the issue, even though the executable already belonged to a secondary group of which I was a member. Note that if you don’t need the advanced features of sqlplus you can still execute PL/SQL with Ant’s sql task.

Subversion on Ubuntu – Multiple Repositories

Eighteen months have passed since I setup Subversion on Ubuntu and I’ve found multiple repositories are valuable for providing finer grained access control and easier storage management. Here is a revised incantation:

su -
adduser --system --home /srv/svnrepos --gecos "System account to run svnserve" svn
apt-get install subversion xinetd
cat >> /etc/xinetd.d/svn << "EOF"
service svn
{
        port                    = 3690
        socket_type             = stream
        protocol                = tcp
        wait                    = no
        user                    = svn
        server                  = /usr/bin/svnserve
        server_args             = -i -r /srv/svnrepos
}
EOF
/etc/init.d/xinetd restart

# for each repository, eg. myrepo1
$repo=myrepo1
svnadmin create /srv/svnrepos/$repo
chown -R svn:nogroup /srv/svnrepos

# uncomment line to use default password file
vi ~svn/$repo/conf/svnserve.conf

cat >> ~svn/$repo/conf/passwd << "EOF"
[users]
fred = *****
...

Windows 7 Backup & Restore

I had my first disk failure this week of my Windows 7 laptop hard drive. Fortunately I’ve been using Windows 7 Backup, and all I had to do was plug in the external USB drive with my backups to another machine, boot off the Windows 7 installation CD, and select ‘Repair…’ using the latest system image from the USB drive. Even restoring a system image from a Dell Latitude to a Toshiba Tecra (with the same sized drive and dual core x64 CPU) was painless, all the necessary drivers were changed automatically with no fuss. The only problem was reestablishing trust with a Windows domain, which was worked around by changing the computer name and re-adding to the domain. The default Windows 7 Backup configuration is to create a system image and backup all files in Libraries, which works just fine for me.

Google Trends – Databases & Languages

Google Trends is a great tool for graphing search term popularity over time. Here is a comparison of searches for several makes of database.

ScreenShot001 

Perhaps it’s a quirk of the phrases I used, but I was surprised to see Oracle so dominant, and even MySQL more popular than SQL Server.  PostgreSQL languishes in obscurity compared to MySQL, and Ingres barely registers at all.

Here’s some languages that I’m interested in.  Java is hugely dominant.

ScreenShot003

Let’s take out Java and zoom in.  I was surprised to see Ruby’s recent decline relative to Python.  Books on Scala have come out only recently.

ScreenShot001

Looking more specifically at JVM language dialects I’m surprised to see Jython competing so strongly with JRuby.  I’m not sure if I picked the right phrase for Groovy.

ScreenShot002

Choosing tools solely on the basis of popularity is obviously not a great idea, but I do feel better now about continuing to use Oracle, Java and Python.

P.S. See also the TIOBE Programming Community Index

Oracle tablespace utilization

I stole this from VS Babu

  SELECT   a.TABLESPACE_NAME,
           a.BYTES bytes_used,
           b.BYTES bytes_free,
           b.largest,
           round( ( ( a.BYTES - b.BYTES ) / a.BYTES ) * 100, 2 ) percent_used
    FROM   (   SELECT   TABLESPACE_NAME, sum( BYTES ) BYTES
                 FROM   dba_data_files
             GROUP BY   TABLESPACE_NAME ) a,
           (   SELECT   TABLESPACE_NAME, sum( BYTES ) BYTES, max( BYTES ) largest
                 FROM   dba_free_space
             GROUP BY   TABLESPACE_NAME ) b
   WHERE   a.TABLESPACE_NAME = b.TABLESPACE_NAME
ORDER BY   ( ( a.BYTES - b.BYTES ) / a.BYTES ) DESC

Thunderbird and Lightning, DavMail & Exchange

Thunderbird is a cross platform email client, Lightning is a calendering add-on.  Lightning will be integrated into Thunderbird 3.  Thunderbird installation is straightforward, Lightning is installed from Thunderbird’s ‘Tools/Add-ons’ menu.

DavMail is an Exchange gateway that wraps standard protocols like IMAP around the proprietary interfaces to Exchange.  DavMail setup is straightforward, following the instructions on it’s website, all I had to provide was the OWA URL.

To configure IMAP in Thunderbird all I had to do was specify a server name of localhost and port of 1143, not 143.  To configure CalDAV I specified a CalDAV location of http://localhost:1080/users/[email protected]/calendar   To configure SMTP for outgoing mail I specified localhost port 1025, not 25.

I couldn’t figure out how to use DavMail LDAP, the documentation is too cryptic. Instead I configured a Thunderbird address book to directly access Active Directory, which works only locally on the LAN.  With the address book available autocompletion works also. 

Trying to replicate the directory for offline access did not work for me, however.  This is supposed to be fixed in a later release.  To work around not having the Exchange address book offline I installed Email Address Crawler which instantly scooped every to or from address from my existing mails into an address book.   I took this home and it worked as expected: I could send and receive mails and had a limited address book.

Having proven this configuration under Windows I installed Ubuntu in a VM and used Synaptic to install Thunderbird. Lightning and DavMail are downloaded and installed the same way as on Windows.  I did, however, run into a defect and workaround installing Lightning.

This solution seems to work OK, but I noticed some issues with the HTML email editor. This is improved in Thunderbird 3, which went into its fourth beta release a few days ago.

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