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MongoDB 2.4 Introduces Geospatial Indexing and Search for GeoJSON Geometries Point, LineString and Polygon

March 6, 2013 by

In case you are unfamiliar with the geospatial stuff, have a look at this introduction to geospatial indexing and searching with MongoDB.

In version 2.4 MongoDB introduces support for a subset of GeoJSON geometries. These geometries can be used both as data and query expressions.

GeoJSON

GeoJSON is a specification for describing geometrical shapes with the help of the JSON (JavaScript Object Notation) format. The basic shapes are points, line strings, polygons and compositions of these shapes. Here are some examples:

// a Point object
{ type: "Point", coordinates: [0.5, 0.5] }
 
// a LineString object
{ type: "LineString", coordinates: [ [100.0, 0.0], [101.0, 1.0] ] }
 
// a simple Polygon object, a box
{ "type": "Polygon",
  "coordinates": [
    [ [0.0, 0.0], [1.0, 0.0], [1.0, 1.0], [0.0, 1.0], [0.0, 0.0] ]
    ]
}

GeoJSON Support in MongoDB

Prior to version 2.4 geospatial data in MongoDB was solely points. You were able to index points denoted by a two-dimensional array ( [1,2] ) or an embedded document with two fields ( {x:1, y:2} ). By using GeoJSON geometries you …
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Tobias Trelle

* category: Big Data, NoSQL | * 4 Comments so far
This post is written on March 6, 2013 by

 

MongoDB Text Search Tutorial

January 10, 2013 by

In my introduction to text search in MongoDB, we had a look at the basic features. Today we’ll have a closer look at the details.

API

You may have noticed that a text search is not executed with a find() command. Instead you call

db.foo.runCommand( "text", {search: "bar"} )

Remember it’s an experimental feature still. Adding it to the implementation of the find() command would have mixed critical production code with the new text search feature. When executed via a runCommand() call, text search can be run and tested in isolation.

I expect to see a new query operator like $text or $textsearch as soon as text search is integrated with the standard find() command.

Text Query Syntax

In the previous examples we just searched for a single word. We can do more than that. Let’s have a look at the following example:

db.foo.drop()
db.foo.ensureIndex( {txt: "text"} )
db.foo.insert( {txt: "Robots are superior to humans"} )
db.foo.insert( {txt: "Humans are weak"} )
db.foo.insert( {txt: "I, Robot - by Isaac Asimov"} )

(read more…)

Tobias Trelle

* category: Big Data, NoSQL, Open Source | * 2 Comments so far
This post is written on January 10, 2013 by

 

MongoDB Text Search Explained

January 7, 2013 by

The upcoming release 2.4 of MongoDB will include a first, experimental support for full text search (FTS). This feature was requested early in the history of MongoDB as you can see from this JIRA ticket: SERVER-380. FTS is first available with the developer release 2.3.2.

Full Text Search 101

Before looking at how MongoDB implemented its initial full text search, we need to learn a little bit about the basics. There are (at least) two important concepts in order to unterstand full text search:

Stop Words

Stop words are used to filter words that are irrelevant for searching. Examples are is, at, the etc. Let’s have a look at the following sentence …

I am your father, Luke

… and these stop words: am, I, your. After applying the stop words, that’s what’s left of our sentence:

father Luke

The remains are processed in the next step. Please note that stop words are langugage dependent and may also vary from domain to domain.
(read more…)

Tobias Trelle

* category: Big Data, NoSQL, Open Source | * 3 Comments so far
This post is written on January 7, 2013 by

 



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