On Thu, Mar 15, 2007 at 07:41:18AM +0100, Peter Eisentraut <peter_e@xxxxxxx> wrote a message of 22 lines which said: > His goal may be to store and compute rational numbers exactly. The > answer is that there is no data type in PostgreSQL that supports > this. But he can write one in PostgreSQL quite easily. Rational numbers are always the first exercice in CS courses about Abstract Data Types :-) http://www.postgresql.org/docs/8.0/interactive/xtypes.html