Package org.apache.sis.storage.aggregate

Class JoinFeatureSet

java.lang.Object
org.apache.sis.storage.AbstractResource
org.apache.sis.storage.AbstractFeatureSet
org.apache.sis.storage.aggregate.JoinFeatureSet
All Implemented Interfaces:
DataSet, FeatureSet, Resource
public class JoinFeatureSet extends AbstractFeatureSet
Features containing association to features from two different sources, joined by a SQL-like JOIN condition. Each feature in this FeatureSet contains two or three properties:
  • An optional identifier created from the identifiers of the left and right features.
  • Zero or one association to a "left" feature.
  • Zero or one association to a "right" feature.
The left and right features appear together in an JoinFeatureSet instance when a value from leftProperty in the first feature is equal to a value from rightProperty in the second feature.

Implementation note

If iterations in one feature set is cheaper than iterations in the other feature set, then the "costly" or larger FeatureSet should be on the left side and the "cheap" FeatureSet should be on the right side.

This implementation is read-only.

Since:
1.0
Version:
1.1
Author:
Johann Sorel (Geomatys), Martin Desruisseaux (Geomatys)

  • Field Details

  • Constructor Details

    • JoinFeatureSet

      public JoinFeatureSet(StoreListeners parent, FeatureSet left, String leftAlias, FeatureSet right, String rightAlias, JoinFeatureSet.Type joinType, BinaryComparisonOperator<? super AbstractFeature> condition, Map<String,?> featureInfo) throws DataStoreException
      Creates a new feature set joining the two given sets. The featureInfo map defines the name, description or other information for the FeatureType created by this method. It can contain all the properties described in DefaultFeatureType plus the following ones:
      • "identifierDelimiter" — string to insert between left and right identifiers in the identifiers generated by the join operation. If this property is not specified, then no identifier will be generated.
      • "identifierPrefix" — string to insert at the beginning of join identifiers (optional).
      • "identifierSuffix" — string to insert at the end of join identifiers (optional).
      Parameters:
      parent - listeners of the parent resource, or null if none.
      left - the first source of features. This is often (but not necessarily) the largest set.
      leftAlias - name of the associations to the left features, or null for a default name.
      right - the second source of features. Should be the set in which iterations are cheapest.
      rightAlias - name of the associations to the right features, or null for a default name.
      joinType - whether values on both sides are required (inner join), or only one side (outer join).
      condition - join condition as property from left feature = property from right feature.
      featureInfo - information about the FeatureType of this feature set.
      Throws:
      DataStoreException - if an error occurred while creating the feature set.

  • Method Details

    • getJoinType

      public JoinFeatureSet.Type getJoinType()
      Specifies whether values on both sides are required (inner join), or only one side (outer join).
      Returns:
      whether values on both sides are required (inner join), or only one side (outer join).

    • getType

      public DefaultFeatureType getType()
      Returns a description of properties that are common to all features in this dataset. This type may contain one identifier and always contains two associations, to the left and right set of features respectively.
      Returns:
      a description of properties that are common to all features in this dataset.

    • features

      public Stream<AbstractFeature> features(boolean parallel) throws DataStoreException
      Returns a stream of all features contained in this dataset.
      Parameters:
      parallel - true for a parallel stream (if supported), or false for a sequential stream.
      Returns:
      all features contained in this dataset.
      Throws:
      DataStoreException - if an error occurred while creating the stream.

    • getEnvelope

      public final Optional<org.opengis.geometry.Envelope> getEnvelope() throws DataStoreException
      Returns the union of the envelopes in all aggregated feature sets. This method tries to find a CRS common to all feature sets. If no common CRS can be found, then the envelope is absent.
      Implementation note: this method is final because overriding it would invalidate the unwrapping of other AggregatedFeatureSet instances. If we wish to allow overrides in a future version, we would need to revisit getEnvelopes(List) first.
      Specified by:
      getEnvelope in interface DataSet
      Overrides:
      getEnvelope in class AbstractResource
      Returns:
      union of envelopes from all dependencies.
      Throws:
      DataStoreException - if an error occurred while computing the envelope.

    • createMetadata

      protected org.opengis.metadata.Metadata createMetadata() throws DataStoreException
      Invoked in a synchronized block the first time that getMetadata() is invoked. The default implementation adds the information documented in the parent class, then adds the dependencies as lineages.
      Overrides:
      createMetadata in class AbstractFeatureSet
      Returns:
      the newly created metadata, or null if unknown.
      Throws:
      DataStoreException - if an error occurred while reading metadata from the data stores.

    • clearCache

      protected void clearCache()
      Clears any cache in this resource, forcing the data to be recomputed when needed again. This method should be invoked if the data in underlying data store changed.
      Overrides:
      clearCache in class AbstractResource