This is an proposal for a little improved partitioning function create_zbx_partitions() shown on:
http://www.zabbix.com/wiki/howto/db/postgres/partition

The attached function has fewer lines of code and allows to create partitions beyond the next one

Usage:
– Create next partition
SELECT create_zbx_partitions();
SELECT create_zbx_partitions(1);

– Create current partition
SELECT create_zbx_partitions(0);

– Create the next but one partition
SELECT create_zbx_partitions(2);