Tadek’s Blog

Coming back home for Christmas I forgot to bring my power supply for my Thinkpad, which made me very unhappy. Hesitating between not switching my computer on at all (BTW: I forgot my books as well ) and getting an expensive power supply, I come up with a home-grown solution.

Thinkpads are quite power-demanding beasts: the power supply has to deliver as much as 16V DC at 4.5A, which rules out most of the non-impulse power supplies you can get. Also 16V is a bit uncommon for any supplies. Fortunately, I noticed that our hallogen lamp uses a 50W transformer, which was almost ideal for my purposes. So I built a simple rectifier and… voila

BTW: 4Amps is quite a current so need to make sure that you use proper diodes, large capacitor and thick cables (there’s about 0.5V voltage loss on my cables).

Recently, I found out that Java the program I wrote ages ago has been alive and kicking and, even more, distributed as a single EXE with an install program. I was a bit surprised, as the last stage I left it it, was only a JAR file (with no sources available)

Looking a bit into it I found out how it can be easily done, which may be useful one day. Not that I want to write Windows programs, but…

* The installation can be done using [Install Creator](http://www.clickteam.com/English/install_creator.htm). The freeware version displays a small ad at the end of the process, but otherwise is free and looks ok.
* For the Java-to-EXE conversion there’s a nice [comparison and discussion](http://www.excelsior-usa.com/articles/java-to-exe.html). In this particular case they used [exe4j](http://www.ej-technologies.com/products/exe4j/overview.html), which is commercial, but there’s a number of other free tools around.

All in all, I must admit they did a good job making my program more user friendly and easier to use. It’s probably a good idea if your target users use a Windows platform (my original program is portable, but I’ve never seen anyone use it on anything but Windows)…

While connecting to PostgreSQL using UnixODBC (from R, but this doesn’t matter) I got the following error:

[unixODBC]client encoding mismatch

It seems that there is some problem with PostgreSQL 8.1 and the encoding names: see [this post](http://archives.postgresql.org/pgsql-odbc/2005-09/msg00161.php) or [google](http://www.google.com/search?q=%22client+encoding+mismatch%22+postgres). It looks that UTF8 used by default with the new Postgres is not compatible with old ODBC drivers. I am not sure where the problem really is, but a _quick fix_ is to change default encoding for the user connecting to the database:

alter user SET client_encoding to LATIN1;

Here’s my list of pointers:

* [Power PostgreSQL](http://www.powerpostgresql.com/Docs/) – really detailed and up-to-date information on setting PostgreSQL runtime parameters. Don’t forget to check the annotated [postgresql.conf](http://www.powerpostgresql.com/Downloads/annotated_conf_80.pdf) with comments. BTW: Looking forward to reading the forthcoming book.
* [Collection of PostgreSQL performance tips](http://archives.postgresql.org/pgsql-sql/2002-04/msg00318.php) – a shopping lists of tips (both configuration as well as application design). The posts is a bit old, but many things (ecpesially the more general ones are still very relevant).
* [Performance Tuning PostgreSQL](http://www.revsys.com/writings/postgresql-performance.html) – a decent link, explaining both runtime settings (some of this might be obsolete) and the general concepts: “EXPLAIN“, “ANALYZE“, indices.
* [Postgres 8.x docs](http://developer.postgresql.org/docs/postgres/runtime-config.html) – explains runtime parameters in some detail.