pgLatLon
diff README.mkd @ 10:684a78d2f9f0
Introduced lossy overlap operator (&&+) and fixed ecircle overlap searches on GiST-indexed ecluster columns
author | jbe |
---|---|
date | Fri Sep 02 14:08:01 2016 +0200 (2016-09-02) |
parents | 2b7aea022117 |
children | 4489b4d7d9c8 |
line diff
1.1 --- a/README.mkd Fri Sep 02 14:04:04 2016 +0200 1.2 +++ b/README.mkd Fri Sep 02 14:08:01 2016 +0200 1.3 @@ -1,4 +1,4 @@ 1.4 -pgLatLon v0.1 documentation 1.5 +pgLatLon v0.3 documentation 1.6 =========================== 1.7 1.8 pgLatLon is a spatial database extension for the PostgreSQL object-relational 1.9 @@ -6,12 +6,15 @@ 1.10 for the WGS-84 spheroid. 1.11 1.12 While many other spatial databases still use imprecise bounding boxes for many 1.13 -operations, pgLatLon supports more precise geometric calculations for all 1.14 -implemented operators. Efficient indexing of geometric objects is provided 1.15 +operations, pgLatLon aims to support more precise geometric calculations for 1.16 +all implemented operators. Efficient indexing of geometric objects is provided 1.17 using space-filling fractal curves. Optimizations on bit level (including 1.18 logarithmic compression) allow for a highly memory-efficient non-overlapping 1.19 index suitable for huge datasets. 1.20 1.21 +pgLatLon is a lightweight solution as it only depends on PostgreSQL itself (and 1.22 +a C compiler for building). 1.23 + 1.24 Unlike competing spatial extensions for PostgreSQL, pgLatLon is available under 1.25 the permissive MIT/X11 license to avoid problems with viral licenses like the 1.26 GPLv2/v3. 1.27 @@ -239,6 +242,24 @@ 1.28 The `&&` operator is commutative, i.e. `a && b` is the same as `b && a`. Each 1.29 commutation is supported as well. 1.30 1.31 +#### Lossy overlap operator `&&+` 1.32 + 1.33 +Tests if two geographic objects may have at least one point in common. Opposed 1.34 +to the `&&` operator, the `&&+` operator may return false positives and is 1.35 +currently implemented for: 1.36 + 1.37 +* `epoint &&+ ecluster` 1.38 +* `ebox &&+ ecircle` 1.39 +* `ebox &&+ ecluster` 1.40 +* `ecircle &&+ ecluster` 1.41 +* `ecluster &&+ ecluster` 1.42 + 1.43 +The `&&+` operator is commutative, i.e. `a &&+ b` is the same as `b &&+ a`. Each 1.44 +commutation is supported as well. 1.45 + 1.46 +Where two data types support both the `&&` and the `&&+` operator, the `&&+` 1.47 +operator computes faster. 1.48 + 1.49 #### Distance operator `<->` 1.50 1.51 Calculates the shortest distance between two geographic objects in meters (zero