In-Memory Indexing

The geomesa-memory module provides a in-memory cache of SimpleFeatures that supports indexing and filtering, using the CQEngine collection query engine. This is implemented by the GeoCQEngine class.

Index Configuration

When creating a GeoCQEngine, the attributes to index are passed in as a list of tuples in the form (name, type), where name corresponds to the attribute name, and type corresponds to the CQEngine index type:

Index Type	Attribute Types	Description
default	Any	Choose index type based on the attribute type being indexed
navigable	Date and numeric types	Supports equality, greater than and less than
radix	String	Supports string matching operations
unique	String, integer or long	Supports unique values. The presence of duplicate values will cause an exception
hash	String, integer or long	Supports equality
geometry	Geometries	Custom index for geometry types

If there is no appropriate index to use for a query, the whole data set will be searched.

Sample usage

import org.geotools.filter.text.ecql.ECQL
import org.locationtech.geomesa.memory.cqengine.GeoCQEngine
import org.locationtech.geomesa.memory.cqengine.utils.CQIndexType
import org.locationtech.geomesa.utils.geotools.SimpleFeatureTypes

// setup
val spec = "Who:String,*Where:Point:srid=4326"
val sft = SimpleFeatureTypes.createType("test", spec)

def buildFeature(sft: SimpleFeatureType, fid: Int): SimpleFeature = ???

// create a new cache
val cq = new GeoCQEngine(sft, Seq(("Who", CQIndexType.DEFAULT), ("Where", CQIndexType.GEOMETRY)))

// add a collection of features
cq.insert(Seq.tabulate(1000)(i => buildFeature(sft, i)))

// add a single feature
val feature = buildFeature(sft, 1001)
cq.insert(feature)

// remove a single feature
cq.remove(feature.getID)

// get an iterator with all features that match a filter
val filter = ECQL.toFilter("Who = 'foo' AND BBOX(Where, 0, 0, 180, 90)")
val reader = cq.query(filter)

// clear the cache
cq.clear()