Precise fractional arithmetic for PostgreSQL

 pg_rational implements precise fractional arithmetic for PostgreSQL. Perfect
 for exact arithmetic or user-specified table row ordering. Holds values as big
 as an integer, with matching precision in the denominator.
 .
 Features:
  * Stores fractions in exactly 64 bits (same size as float)
  * Written in C for high performance
  * Detects and halts arithmetic overflow for correctness
  * Uses native CPU instructions for fast overflow detection
  * Defers GCD calculation until requested or absolutely required
  * Supports btree and hash indices
  * Implements Stern-Brocot trees for finding intermediate points
  * Coercion from integer/bigint/tuple
  * Custom aggregate