seg

Overview

Version

Install

Note: This is a built-in contrib extension of PostgreSQL

CREATE EXTENSION seg;

Usage

seg: line segment / floating-point interval data type

The seg extension provides a data type for representing line segments or floating-point intervals, useful for representing measurements with uncertainty.

CREATE EXTENSION seg;

Input Formats

SELECT '5.0'::seg;           -- zero-length interval (point)
SELECT '5.0 .. 7.0'::seg;    -- interval from 5.0 to 7.0
SELECT '5(+-)0.3'::seg;      -- interval 4.7 .. 5.3
SELECT '50 ..'::seg;          -- open interval >= 50
SELECT '.. 0'::seg;           -- open interval <= 0

Certainty indicators (<, >, ~) can be prepended but are treated as comments and ignored by operators.

Operators

Spatial operators (GiST-indexed):

Comparison operators (<, <=, >, >=) are available for sorting.

Index Support

CREATE INDEX idx ON measurements USING gist (reading);

Precision

Values are stored as 32-bit floating-point pairs, retaining up to 7 significant digits. Trailing zeroes are preserved.