Package org.apache.druid.query.extraction

Class MapLookupExtractor

java.lang.Object

org.apache.druid.query.lookup.LookupExtractor

org.apache.druid.query.extraction.MapLookupExtractor

public class MapLookupExtractor
extends LookupExtractor

Lookup extractor backed by any kind of map. When the map is immutable, use ImmutableLookupMap instead.

Constructor Summary

Constructors

Constructor	Description
MapLookupExtractor(Map<String,String> map, boolean isOneToOne)

Method Summary

Modifier and Type	Method	Description
String	apply(String key)	Apply a particular lookup methodology to the input string
Map<String,String>	asMap()	Returns a Map view of this lookup extractor.
boolean	equals(Object o)
long	estimateHeapFootprint()	Estimated heap footprint of this object.
static <K,V> long	estimateHeapFootprint(Iterable<Map.Entry<K,V>> entries)	Estimate the heap footprint of a Map.
byte[]	getCacheKey()	Create a cache key for use in results caching
Map<String,String>	getMap()
int	hashCode()
boolean	isOneToOne()
boolean	supportsAsMap()	Returns whether this lookup extractor's LookupExtractor.asMap() will return a valid map.
List<String>	unapply(String value)	Reverse lookup from a given value.
Iterator<String>	unapplyAll(Set<String> values)	Reverse lookup from a given set of values.

Methods inherited from class org.apache.druid.query.lookup.LookupExtractor

applyAll

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MapLookupExtractor

public MapLookupExtractor(Map<String,String> map,
                          boolean isOneToOne)

Method Detail

estimateHeapFootprint

public static <K,V> long estimateHeapFootprint(Iterable<Map.Entry<K,V>> entries)

Estimate the heap footprint of a Map. Important note: the implementation accepts any kind of map entries, but estimates zero footprint for keys and values of types other than String.

getMap

public Map<String,String> getMap()

apply

@Nullable
public String apply(@Nullable
                    String key)

Description copied from class: LookupExtractor

Apply a particular lookup methodology to the input string

Specified by:

apply in class LookupExtractor

Parameters:

key - The value to apply the lookup to.

Returns:

The value for this key, or null when key is `null` in NullHandling.sqlCompatible() mode, or when key cannot have the lookup applied to it and should be treated as missing.

unapply

public List<String> unapply(@Nullable
                            String value)

Description copied from class: LookupExtractor

Reverse lookup from a given value. Used by the default implementation of LookupExtractor.unapplyAll(Set). Otherwise unused. Implementations that override LookupExtractor.unapplyAll(Set) may throw UnsupportedOperationException from this method.

Specified by:

unapply in class LookupExtractor

Parameters:

value - the value to apply the reverse lookup. NullHandling.emptyToNullIfNeeded(String) will have been applied to the value.

Returns:

the list of keys that maps to the provided value. In SQL-compatible null handling mode, null keys are omitted.

unapplyAll

@Nullable
public Iterator<String> unapplyAll(Set<String> values)

Description copied from class: LookupExtractor

Reverse lookup from a given set of values.

Overrides:

unapplyAll in class LookupExtractor

Parameters:

values - set of values to reverse lookup. NullHandling.emptyToNullIfNeeded(String) will have been applied to each value.

Returns:

iterator of keys that map to to the provided set of values. May contain duplicate keys. Returns null if this lookup instance does not support reverse lookups. In SQL-compatible null handling mode, null keys are omitted.

isOneToOne

public boolean isOneToOne()

Overrides:

isOneToOne in class LookupExtractor

getCacheKey

public byte[] getCacheKey()

Description copied from class: LookupExtractor

Create a cache key for use in results caching

Specified by:

getCacheKey in class LookupExtractor

Returns:

A byte array that can be used to uniquely identify if results of a prior lookup can use the cached values

supportsAsMap

public boolean supportsAsMap()

Description copied from class: LookupExtractor

Returns whether this lookup extractor's LookupExtractor.asMap() will return a valid map.

Specified by:

supportsAsMap in class LookupExtractor

asMap

public Map<String,String> asMap()

Description copied from class: LookupExtractor

Returns a Map view of this lookup extractor. The map may change along with the underlying lookup data.

Specified by:

asMap in class LookupExtractor

estimateHeapFootprint

public long estimateHeapFootprint()

Description copied from class: LookupExtractor

Estimated heap footprint of this object. Not guaranteed to be accurate. For example, some implementations return zero even though they do use on-heap structures. However, the most common classes, MapLookupExtractor and ImmutableLookupMap, do have reasonable implementations. This API is provided for best-effort memory management and monitoring.

Overrides:

estimateHeapFootprint in class LookupExtractor

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object