Package org.apache.druid.query.extraction

Class IdentityExtractionFn

java.lang.Object
org.apache.druid.query.extraction.IdentityExtractionFn
All Implemented Interfaces:
Cacheable, ExtractionFn
public class IdentityExtractionFn extends Object implements ExtractionFn

  • Method Details

    • getCacheKey

      public byte[] getCacheKey()
      Description copied from interface: Cacheable
      Get a byte array used as a cache key.
      Specified by:
      getCacheKey in interface Cacheable
      Returns:
      bytes to be used as cache key - or null if this object should not be cached.

    • apply

      @Nullable public String apply(@Nullable Object value)
      Description copied from interface: ExtractionFn
      The "extraction" function. This should map an Object into some String value.

      In order to maintain the "null and empty string are equivalent" semantics that Druid provides, the empty string is considered invalid output for this method and should instead return null. This is a contract on the method rather than enforced at a lower level in order to eliminate a global check for extraction functions that do not already need one.

      Specified by:
      apply in interface ExtractionFn
      Parameters:
      value - the original value of the dimension
      Returns:
      a value that should be used instead of the original

    • apply

      @Nullable public String apply(@Nullable String value)
      Description copied from interface: ExtractionFn
      The "extraction" function. This should map a String value into some other String value.

      Like ExtractionFn.apply(Object), the empty string is considered invalid output for this method and it should instead return null.

      Specified by:
      apply in interface ExtractionFn
      Parameters:
      value - the original value of the dimension
      Returns:
      a value that should be used instead of the original

    • apply

      public String apply(long value)
      Description copied from interface: ExtractionFn
      The "extraction" function. This should map a long value into some String value.

      Like ExtractionFn.apply(Object), the empty string is considered invalid output for this method and it should instead return null.

      Specified by:
      apply in interface ExtractionFn
      Parameters:
      value - the original value of the dimension
      Returns:
      a value that should be used instead of the original

    • preservesOrdering

      public boolean preservesOrdering()
      Description copied from interface: ExtractionFn
      Offers information on whether the extraction will preserve the original ordering of the values.

      Some optimizations of queries is possible if ordering is preserved. Null values *do* count towards ordering.

      Specified by:
      preservesOrdering in interface ExtractionFn
      Returns:
      true if ordering is preserved, false otherwise

    • getExtractionType

      public ExtractionFn.ExtractionType getExtractionType()
      Description copied from interface: ExtractionFn
      A dim extraction can be of one of two types, renaming or rebucketing. In the `ONE_TO_ONE` case, a unique values is modified into another unique value. In the `MANY_TO_ONE` case, there is no longer a 1:1 relation between old dimension value and new dimension value
      Specified by:
      getExtractionType in interface ExtractionFn
      Returns:
      ExtractionFn.ExtractionType declaring what kind of manipulation this function does

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • equals

      public boolean equals(Object o)
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • getInstance

      public static IdentityExtractionFn getInstance()