com.sleepycat.client

Interface SSecondaryKeyCreator

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface SSecondaryKeyCreator

The interface implemented for extracting single-valued secondary keys from primary records.

The key creator object is specified by calling SSecondaryConfig.setKeyCreator(com.sleepycat.client.SSecondaryKeyCreator). The secondary database configuration is specified when calling SEnvironment.openSecondaryDatabase(com.sleepycat.client.STransaction, java.lang.String, java.lang.String, com.sleepycat.client.SDatabase, com.sleepycat.client.SSecondaryConfig).

For example:

  class MyKeyCreator implements SSecondaryKeyCreator {
      public boolean createSecondaryKey(SSecondaryDatabase secondary,
              SDatabaseEntry key,
              SDatabaseEntry data,
              SDatabaseEntry result) throws SDatabaseException {
          //
          // DO HERE: Extract the secondary key from the primary key and
          // data, and set the secondary key into the result parameter.
          //
          return true;
      }
  }
  ...
  SSecondaryConfig secConfig = new SSecondaryConfig();
  secConfig.setKeyCreator(new MyKeyCreator());
  // Now pass secConfig to SEnvironment.openSecondaryDatabase
 

Method Summary

Modifier and Type	Method and Description
boolean	createSecondaryKey(SSecondaryDatabase secondary, SDatabaseEntry key, SDatabaseEntry data, SDatabaseEntry result) Creates a secondary key entry, given a primary key and data entry.

Method Detail

createSecondaryKey

boolean createSecondaryKey(SSecondaryDatabase secondary,
                           SDatabaseEntry key,
                           SDatabaseEntry data,
                           SDatabaseEntry result)
                    throws SDatabaseException

Creates a secondary key entry, given a primary key and data entry.

A secondary key may be derived from the primary key, primary data, or a combination of the primary key and data. For secondary keys that are optional, the key creator method may return false and the key/data pair will not be indexed. To ensure the integrity of a secondary database the key creator method must always return the same result for a given set of input parameters.

Parameters:

secondary - the database to which the secondary key will be added. This parameter is passed for informational purposes but is not commonly used.

key - the primary key entry. This parameter must not be modified by this method.

data - the primary data entry. This parameter must not be modified by this method.

result - the secondary key created by this method.

Returns:

true if a key was created, or false to indicate that the key is not present.

Throws:

SDatabaseException - if an error occurs attempting to create the secondary key.