Artem Russakovskii's programming and technology blog

The Problem

If you use VNC to remotely connect to your machines and are having problems with certain applications not showing changes (redrawing), this will, hopefully, solve the problem for you.

The symptoms are simple: you load a program but only the program outline and maybe the first frame would show up. After that, nothing would update, even though the user in front of the remote computer can see everything updating fine. For me, it is happening with all Java based programs (SmartSVN, Charles – amazing program btw!, etc). Here's what's happening to my Charles application – it never even sent the first frame, simply showing the desktop and not updating:

The problem may be confined to RealVNC …

The Problem

I use a lot of extensions. A LOT. They slow down my Firefox while giving something useful in return. Most of them are harmless and do not affect the speed too much but there are select few that are just CPU, memory, and performance hogs.

Until Firefox gets an extension manager that can show what the impact from each extension on time/CPU/memory is, one can resort to guessing, disabling, testing, and looking for clues to find these conniving little bastards.

Anyway, so where was I? Recently, my Firefox became increasingly unresponsive, especially when switching tabs. After some time, it was a pain to switch tabs altogether, so I had to resort to restarting the browser, only to …

Introduction

A question I recently saw on Stack Overflow titled Faster way to delete matching [database] rows? prompted me to organize my thoughts and observations on the subject and quickly jot them down here.

Here is the brief description of the task: say, you have 2 MySQL tables a and b. The tables contain the same type of data, for example log entries. Now you want to delete all or a subset of the entries in table a that exist in table b.

Solutions Suggested By Others

DELETE FROM a WHERE EXISTS (SELECT b.id FROM b WHERE b.id = a.id);

DELETE a