Bejegyzések

Bejegyzések megjelenítése ebből a hónapból: január, 2013

ERROR: "Problem with InfiniDB process PrimProc, should be a single version running"

InfiniDB Infinibd is a column-oriented database (actually a MySQL storage engine, or to be more precise, a MySQL distribution with this special storage engine). It can handle analytical / reporting queries very well. ERROR I installed it on my laptop to form a nice data warehouse / reporting development environment together with Pentaho's tools. It did OK for a while, but it seized to work about a week ago. Upon startup, the /etc/init.d/infinidb script gave this error message: Problem with InfiniDB process PrimProc, should be a single version running

Implementing a Hilbert (90 degree shift) filter in Python

Why? A digital 90° phase shift filter is an important building block of the so-called Software Defined Radios (SDRs). And SDR is a radio that has (relatively) minimal hardware, and most of the features are implemented in software. There are no fancy buttons and displays, but there is a UI application that controls the box. The box is a direct conversion receiver. It just converts part of the radio frequency spectrum to the audio spectrum (the reality is a bit more complicated, but you got the idea). An SDR usually provides two signals that are almost the same, except one signal's frequency components are shifted 90 degrees in one direction. Given these two audio signals, the software can do anything a conventional receiver can achieve with bulky components or expensive integrated circuits. Plus, the software can be changed easily. Actually this is the greatest thing in SDRs. The software can demodulate AM signals by LW-MW-SW broadcast stations, or FM usually encountered

Converting a dual-boot MBR partitioned disk to GPT

Background story I always liked computer games. My first PC was a Pentium 100 MHz machine with very little RAM, which was dedicated almost entirely to a RAM disk. My first precious PC was lacking a hard drive. Every time I wanted to use it, I had to boot up from a floppy and copy software from a few other floppies to the RAM disk. One of my favourite games was UFO: Enemy Unknown. It took a lot of time to boot and copy everything in place, so my machine was on most of the time, and I played a lot on it :) This kinda shows my commitment to PC games. The famous game was recently rebooted by Firaxis as "XCOM: Enemy Unkown". The game was kinda sluggish on my current setup, so I decided to buy new hardware.

ERROR: Pentaho Data Integration (Kettle) process runs twice

The Problem I work a lot with Pentaho Data Integration a.k.a Kettle toolkit. For those who don't known: Kettle allows you to build processes with a GUI that can be run in the IDE or from the command line, and reads data, converts and transforms it, then spits it out. It can deal with a lot of databases and various file formats, can invoke shell scripts, can run JavaScript snippets, and perform various conversions and transformations. Very handy when you have to load large, broken CSV files into relational databases just to mention an example. I recently re-designed one of our processes (or "jobs" in Kettle) when something really strange showed up during testing. Part of the process run twice. It seemed like I'd duplicated the whole process from some point. The IDE is basicly allows you to build a graph, the nodes are the process steps, the edges are telling what to do when a node was finished. Clearly, beside error handling edges, I only draw a single edge