acogitosis

Solution to Postgres JDBC driver ignoring charSet directive with SQL_ASCII database

Grzegorz — Fri, 18 Nov 2011 17:10:21 +0000

“New” Postgres JDBC drivers check database engine version and if it’s not below 7.3 they will ignore charSet declaration. It breaks encoding of 8-bit characters if database has SQL_ASCII encoding (which basically means DONT_CARE_ANYTHING_GOES). If your database is set to SQL_ASCII and in reality it stores e.g. Windows-1250 (CP1250) characters, JDBC driver will assume incorrect encoding and diacritical characters will be broken.

Even though I understand the reasons given by Postgres developers for this (SQL_ASCII is NOT supposed to be used with anything other than 7-bit characters and it is obsolete), the solution they’re suggesting (to dump the db, and convert it to UTF-8) is not always possible. For instance, I would have a hard time telling my customer to do it, especially because their old software might break.

So I’ve patched the JDBC driver to accept charSet directive in JDBC URLs and also added a method setCharset to PGSimpleDataSource.

Here you can download it: Postgres JDBC driver - charSet patched

[en] Java: File.renameTo() doesn’t work on Linux between partitions

Grzegorz — Wed, 11 May 2011 15:50:20 +0000

I have /tmp and /home on different partitions. When trying to move a file from /tmp to /home using File.renameTo() — it fails. Turns out one has to copy and delete the file himself, renameTo works only inside single partition.

Notka dla siebie - układanie okienek w Ubuntu

Grzegorz — Mon, 20 Dec 2010 17:28:30 +0000

http://www.giuspen.com/x-tile/

Dużo RAMu na Ubuntu i sysctl.conf

Grzegorz — Fri, 17 Dec 2010 00:24:24 +0000

Notka dla siebie - czy takie zmiany w /etc/sysctl.conf faktycznie przyspieszą działanie Ubuntu na komputerze z mnóstwem ramu?

vm.swappiness=10 vm.vfs_cache_pressure=50

Hmmm

Grzegorz — Sat, 11 Dec 2010 10:46:34 +0000

[en] Fix jQuery’s $.get() not working in IE (Internet Explorer)

Grzegorz — Fri, 10 Dec 2010 21:11:42 +0000

It turns out that Internet Explorer caches AJAX requests (how clever). If you’re using $.ajax(), you can pass cache: false option to it, but if - like me - you’re using $.get() and $.post(), just use

$.ajaxSetup({cache: false});

somewhere at the start of your script.

[en] Using ffmpeg to convert AVI video to FLV using H.264 and reasonable bitrates

Grzegorz — Wed, 08 Dec 2010 20:33:33 +0000

Mostly for my future reference. -threads 8 should be changed to the number of CPU cores (my i7 has 4 with HT, thus I set it to 8).

ffmpeg -i input.avi -acodec libfaac -ab 48k -vcodec libx264 -vpre fast -vb 500k -threads 8 -f flv output.flv

[en] Fixing Ubuntu boot process after restoring tar backups to newly formatted disk (with UUID changed)

Grzegorz — Wed, 28 Jul 2010 17:40:19 +0000

Mostly note to my self for future reference.

What they don’t tell You in the tar backup tutorial is that it’s not enough to edit /etc/fstab (and their instructions for grub are for grub-legacy).

Because after restoring you probably have new partition UUIDs, you must:

boot livecd
mount your root fs
mount -B /dev /rootfs/dev, etc. (with proc and sys at least) to be able to chroot from livecd to your root fs
chroot /rootfs
edit /etc/fstab and change UUIDs there (new ones you can get using blkid
do sudo dpkg-reconfigure -plow grub-pc to automatically upgrade grub config files, just let it install to the drive(s) it was on
do update-initramfs -u so UUID stored inside initramfs get updated, too

Then you should be able to boot it.

[en] Fixing VirtualBox 3.1, 3.2 (and others?) slowness for Ubuntu host and Windows XP guest

Grzegorz — Thu, 08 Jul 2010 19:30:44 +0000

Install VirtualBox Guest Additions in Windows’ safe-mode so system file protection doesn’t interfere with the installation, it’s that simple and fixed all my VirtualBox performance problems.

[en] Fix PNG images dark in IE

Grzegorz — Fri, 26 Jun 2009 10:29:14 +0000

IE can’t do anything right. If you save some graphical elements to PNG, and try to put them on an area with CSS-defined color, there will be a difference even if you used the same color in the PNG — IE renders PNGs darker than it should. The reason for this is misinterpretation of gAMA frame saved in PNGs that makes it possible to better color-match pictures. The fix is to remove this frame, and doing it on Ubuntu is as easy as:

aptitude install pngcrush cd your-graphics-directory mkdir fixed find . -type f -exec pngcrush -d fixed -rem cHRM -rem gAMA -rem iCCP -rem sRGB {} \;

Now you have a “fixed” directory where you have PNGs that will work properly in IE (and are a bit smaller which is a nice side effect). If you’re sure they’re ok, just do

mv fixed/* ./ rmdir fixed

That’s all.