pgLatLon
changeset 11:7c1c76e7d341
Updated README.html file (from README.mkd)
| author | jbe |
|---|---|
| date | Fri Sep 02 14:08:17 2016 +0200 (2016-09-02) |
| parents | 684a78d2f9f0 |
| children | b4ec52e7e888 |
| files | README.html |
line diff
1.1 --- a/README.html Fri Sep 02 14:08:01 2016 +0200 1.2 +++ b/README.html Fri Sep 02 14:08:17 2016 +0200 1.3 @@ -1,17 +1,20 @@ 1.4 -<html><head><title>pgLatLon v0.1 documentation</title></head><body> 1.5 -<h1>pgLatLon v0.1 documentation</h1> 1.6 +<html><head><title>pgLatLon v0.3 documentation</title></head><body> 1.7 +<h1>pgLatLon v0.3 documentation</h1> 1.8 1.9 <p>pgLatLon is a spatial database extension for the PostgreSQL object-relational 1.10 database management system providing geographic data types and spatial indexing 1.11 for the WGS-84 spheroid.</p> 1.12 1.13 <p>While many other spatial databases still use imprecise bounding boxes for many 1.14 -operations, pgLatLon supports more precise geometric calculations for all 1.15 -implemented operators. Efficient indexing of geometric objects is provided 1.16 +operations, pgLatLon aims to support more precise geometric calculations for 1.17 +all implemented operators. Efficient indexing of geometric objects is provided 1.18 using space-filling fractal curves. Optimizations on bit level (including 1.19 logarithmic compression) allow for a highly memory-efficient non-overlapping 1.20 index suitable for huge datasets.</p> 1.21 1.22 +<p>pgLatLon is a lightweight solution as it only depends on PostgreSQL itself (and 1.23 +a C compiler for building).</p> 1.24 + 1.25 <p>Unlike competing spatial extensions for PostgreSQL, pgLatLon is available under 1.26 the permissive MIT/X11 license to avoid problems with viral licenses like the 1.27 GPLv2/v3.</p> 1.28 @@ -249,6 +252,26 @@ 1.29 <p>The <code>&&</code> operator is commutative, i.e. <code>a && b</code> is the same as <code>b && a</code>. Each 1.30 commutation is supported as well.</p> 1.31 1.32 +<h4>Lossy overlap operator <code>&&+</code></h4> 1.33 + 1.34 +<p>Tests if two geographic objects may have at least one point in common. Opposed 1.35 +to the <code>&&</code> operator, the <code>&&+</code> operator may return false positives and is 1.36 +currently implemented for:</p> 1.37 + 1.38 +<ul> 1.39 +<li><code>epoint &&+ ecluster</code></li> 1.40 +<li><code>ebox &&+ ecircle</code></li> 1.41 +<li><code>ebox &&+ ecluster</code></li> 1.42 +<li><code>ecircle &&+ ecluster</code></li> 1.43 +<li><code>ecluster &&+ ecluster</code></li> 1.44 +</ul> 1.45 + 1.46 +<p>The <code>&&+</code> operator is commutative, i.e. <code>a &&+ b</code> is the same as <code>b &&+ a</code>. Each 1.47 +commutation is supported as well.</p> 1.48 + 1.49 +<p>Where two data types support both the <code>&&</code> and the <code>&&+</code> operator, the <code>&&+</code> 1.50 +operator computes faster.</p> 1.51 + 1.52 <h4>Distance operator <code><-></code></h4> 1.53 1.54 <p>Calculates the shortest distance between two geographic objects in meters (zero