pbzip2: parallel bzipping

Probably this software existed for a quite long time but I didn’t know its existence ’til now: pbzip2
it’s basically a bzip2 algorithm implementation with pthreads support. This mean, in a always more SMP world, that you can greatly improve your bzipping perfomances (divide the zipping time by the number of cores you have et voilà!)

Compression syntax is totally compatible:

$ pbzip2 big.file


while to unzip you have to do

$ pbzip2 -d big.file.bz2


Use with caution (or with -l and -p switches) cause you can easily saturate your 4xSix-cores monster.

HOWTO: Ethernet bonding in Debian Lenny

In an older post I explained how to create a bond interface in Debian Etch… now, this doesn’t work anymore due to some changes in Lenny.

So, long story short, first of all, install ifenslave

# apt-get install ifenslave-2.6


edit /etc/network/interfaces and add the bond0 config:

auto bond0
iface bond0 inet static
address 192.168.1.2
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.1
# dns-* options are implemented by the resolvconf package, if installed
dns-nameservers 192.168.1.1
up /sbin/ifenslave bond0 eth0 eth1
down /sbin/ifenslave -d bond0 eth0 eth1


now edit /etc/modprobe.d/arch/x86_64 (change the filename depending on your architecture) and add these lines


alias bond0 bonding
options bonding mode=1 miimon=100 downdelay=200 updelay=200


Brief explanation:

• miimon N: check if the active interface(s) is alive every N milliseconds
• downdelay N: wait N milliseconds after a detected link failure to consider the link down
• updelay N: wait N milliseconds after a detected link restoration to consider the link up
• mode N: 1 means master/slave configuration, so there’s only one active master. If this link fails, then slave is used.

For a more complete description of all the possible parameters, refer to Linux Documentation/networking/bonding.txt

After this, you can restart networking or reboot if you are working remotely and it should work without a problem. It did for me :)

Column names with trailing spaces in tables and views

Just found out a bizarre feature of MySQL: you simply cannot create a table with a trailing space in a column name. Something like this, doesn’t work:

create table a (`a ` int);
ERROR 1166 (42000): Incorrect column name 'a '


There’s a thread in MySQL’s lists explaining it

Ok, it seems there’s a technical limitation but this solution seems like a lazy workaround to me.
The problem is with CREATE VIEW. In recent MySQL builds you cannot either create a view with a trailing space in a column name. But recent means, at least, greater than 5.0.51a, cause this version DOES let you create a view with a trailing space.

# mysql --version
mysql Ver 14.12 Distrib 5.0.51a, for debian-linux-gnu (x86_64) using readline 5.2

mysql> create view b as select a `a ` from a;
Query OK, 0 rows affected (0.00 sec)


There’s a big problem here: 5.0.51a is the default and supported version in Debian Lenny! So, if you have Lenny as a master of a more recent MySQL installation, be careful cause a CREATE VIEW with a trailing space in a column name will break your replication. Grrrr. MySQL, I hate you, really.