Exporting Data from PostgreSQL Database to Matlab

To use the PostgreSQL database under Windows, you must select the package from the cygwin installation.
To link a database with Matlab, you need the Database toolbox distributed with Matlab.*

Instructions

(derived from Matlab's Help files on Database Toolbox and Logger.java written by Terence Tong)

Edit the classpath used by MATLAB such that you load the JDBC drivers (they are used for connecting to the database).

In UNIX, find the location of any files named *jdbc*.jar (* stands for wildcards)

You will likely use the one in tinyos-1.x/tools/java/jars/pgjdbc2.jar
You probably should NOT use /usr/share/postgresql/java/postgresql.jar ... at least I haven't had any luck with it

In MATLAB, type in edit classpath.txt to open up the MATLAB editor and add the path to the JAR file containing the JDBC drivers to the top of the list.

The file should look something like this.

Close and restart MATLAB.

copy the file importDB.m to your matlab working directory. Use this as a sample of how to access the database. You should modify this file to suit your purposes.
Remember to start up the database using startdb at the UNIX prompt before trying to connect to it through MATLAB.

Miscellaneous Help:

Simple PostgreSQL commands

If you get annoyed by the error messages from disconnecting the database abruptly:

LOG: could not receive data from client: Connection reset by peer
LOG: unexpected EOF on client connection

and you dislike the screen scrolling by blank spaces every time a packet is received, copy the new Logger.java into the RSC dircectory and compile it with javac. This version prompts you to close the database connection by typing in 'quit' and uses x's instead of blank lines to signify that a packet was received.
To stop the old logger.sh from logging, just hit Ctrl-C.
To stop the database which is started by startdb, you need to type 'ps' to find the process id for postgres and explicitly kill the process called 'postgres' using kill process_id. This is basically how it's done in the postgres manual.
Currently, MATLAB does not handle selecting the "time" column of the tables in the database very well - It gives an error, probably because the format of the data is incorrect. Currently, I do not know a quick hack for the problem.

* People have also written their own Matlab interfaces to Postgres and posted them online. I have not tested any of these.
Potentially useful sites for interfacing without the Database Toolbox:

http://www.dertech.com/pgmex/pgmex.html
http://www.math.toronto.edu/almgren/mysql/
On MatlabCentral's File Exchange, the project named "postgres to MATLAB" by Rodrigo Oliveira