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