Examples of com.sleepycat.je.SecondaryKeyCreator

com.sleepycat.je.SecondaryKeyCreator

O HERE: Extract the secondary key from the primary key and // data, and set the secondary key into the result parameter. // return true; } } ... SecondaryConfig secConfig = new SecondaryConfig(); secConfig.setKeyCreator(new MyKeyCreator()); // Now pass secConfig to Environment.openSecondaryDatabase

Use this interface when zero or one secondary key is present in a single primary record, in other words, for many-to-one and one-to-one relationships. When more than one secondary key may be present (for many-to-many and one-to-many relationships), use the {@link SecondaryMultiKeyCreator} interface instead. The table below summarizes howto create all four variations of relationships.

Relationship	Interface	Duplicates	Example
One-to-one	{@link SecondaryKeyCreator}	No	A person record with a unique social security number key.
Many-to-one	{@link SecondaryKeyCreator}	Yes	A person record with a non-unique employer key.
One-to-many	{@link SecondaryMultiKeyCreator}	No	A person record with multiple unique email address keys.
Many-to-many	{@link SecondaryMultiKeyCreator}	Yes	A person record with multiple non-unique organization keys.

To configure a database for duplicates. pass true to {@link DatabaseConfig#setSortedDuplicates}.

WARNING: Key creator instances are shared by multiple threads and key creator methods are called without any special synchronization. Therefore, key creators must be thread safe. In general no shared state should be used and any caching of computed values must be done with proper synchronization.

    // 单个关键字索引表允许重复的记录
    SecondaryConfig config = new SecondaryConfig();
    config.setAllowCreate(true);
    config.setTransactional(true);
    config.setSortedDuplicates(true);
    config.setKeyCreator(new SecondaryKeyCreator() {


      public boolean createSecondaryKey(SecondaryDatabase secondary,
          DatabaseEntry key, DatabaseEntry data, DatabaseEntry result)
          throws DatabaseException {
        String name = secondary.getDatabaseName();

    mySecConfig.setSortedDuplicates(true);


    /*
     * Get a secondary object and set the key creator on it.
     */
    SecondaryKeyCreator firstKeyCreator = new MyFirstKeyCreator();
    mySecConfig.setKeyCreator(firstKeyCreator);
    


    firstKeyIndex = BerkeleyDBFactory.getEnv().openSecondaryDatabase(null,
        "matrix_first_key", db, mySecConfig);
    
    /*
     * Get a secondary object and set the key creator on it.
     */
    SecondaryKeyCreator secondKeyCreator = new MySecondaryKeyCreator();
    mySecConfig.setKeyCreator(secondKeyCreator);
    
    secondKeyIndex = BerkeleyDBFactory.getEnv().openSecondaryDatabase(null,
        "matrix_second_key", db, mySecConfig);

Related Classes of com.sleepycat.je.SecondaryKeyCreator

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