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

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