Package org.datanucleus.store.rdbms.valuegenerator

Class TableGenerator

  • All Implemented Interfaces:
    org.datanucleus.store.valuegenerator.ValueGenerator<Long>
    public final class TableGenerator
extends org.datanucleus.store.valuegenerator.AbstractConnectedGenerator<Long>
    Identity generator for RDBMS databases that generates ids using a table in the database. This generator is coupled to core and can't be used in standalone mode.

    The following properties define the name of the sequence being generated. If "sequence-name" is specified then it is used. Otherwise the name of the sequence will either be based on the table name or the class name (for what we are generating the ids).

    • sequence-name - Name for the sequence
    • sequence-table-basis - Basic for the sequence name (if "sequence-name" not provided). This can be "table" or "class".

    The following properties define the table where the identities are generated.

    • sequence-catalog-name - the catalog name for the table (defaults to the default catalog)
    • sequence-schema-name - the schema name for the table (defaults to the default schema)
    • sequence-table-name - the table name for the table (defaults to SEQUENCE_TABLE)
    • sequence-name-column-name - the name for the column that represent sequence names
    • sequence-nextval-column-name - the name for the column that represent incrementing sequence values

    The following properties control the initial value, and the number of ids that are cached (generated) in each call.

    • key-initial-value - start value (if we have no current value). If not specified and we have no current value then we do a "SELECT max(column-name) FROM table-name" for the column being incremented
    • key-cache-size - number of unique identifiers to cache (defaults to 5)

    The following properties are used when finding the starting point for the identities generated.

    • table-name - name of the table whose column we are generating the value for
    • column-name - name of the column that we are generating the value for
    TODO Change structure to not override obtainGenerationBlock so we can follow the superclass process and commonise more code.

    • Nested Class Summary

      • Nested classes/interfaces inherited from class org.datanucleus.store.valuegenerator.AbstractConnectedGenerator

        org.datanucleus.store.valuegenerator.AbstractConnectedGenerator.ConnectionPreference

    • Field Summary

      Fields 
      Modifier and Type Field Description
      protected org.datanucleus.store.connection.ManagedConnection connection
      Connection to the datastore.
      static String DEFAULT_NEXTVALUE_COLUMN_NAME
      Default name for the column storing the next value of the sequence.
      static String DEFAULT_SEQUENCE_COLUMN_NAME
      Default name for the column storing the name of the sequence.
      static String DEFAULT_TABLE_NAME
      Default name for the datastore table storing the sequence values.
      protected boolean repositoryExists
      Flag for whether we know that the repository exists.

      • Fields inherited from class org.datanucleus.store.valuegenerator.AbstractConnectedGenerator

        connectionProvider, properties

      • Fields inherited from class org.datanucleus.store.valuegenerator.AbstractGenerator

        allocationSize, block, initialValue, name, storeMgr

      • Fields inherited from interface org.datanucleus.store.valuegenerator.ValueGenerator

        PROPERTY_CATALOG_NAME, PROPERTY_CLASS_NAME, PROPERTY_COLUMN_NAME, PROPERTY_FIELD_NAME, PROPERTY_KEY_CACHE_SIZE, PROPERTY_KEY_DATABASE_CACHE_SIZE, PROPERTY_KEY_INITIAL_VALUE, PROPERTY_KEY_MAX_VALUE, PROPERTY_KEY_MIN_VALUE, PROPERTY_ROOT_CLASS_NAME, PROPERTY_SCHEMA_NAME, PROPERTY_SEQUENCE_NAME, PROPERTY_SEQUENCETABLE_CATALOG, PROPERTY_SEQUENCETABLE_NAME_COLUMN, PROPERTY_SEQUENCETABLE_NEXTVAL_COLUMN, PROPERTY_SEQUENCETABLE_SCHEMA, PROPERTY_SEQUENCETABLE_TABLE, PROPERTY_TABLE_NAME

    • Constructor Summary

      Constructors 
      Constructor Description
      TableGenerator​(org.datanucleus.store.StoreManager storeMgr, String name, Properties props)
      Constructor.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      protected boolean createRepository()
      Method to create the repository for ids to be stored.
      static Class getStorageClass()
      Accessor for the storage class for values generated with this generator.
      SequenceTable getTable()
      Convenience accessor for the table being used.
      protected void initialiseSequenceTable()
      Method to initialise the sequence table used for storing the sequence values.
      protected org.datanucleus.store.valuegenerator.ValueGenerationBlock<Long> obtainGenerationBlock​(int number)
      Get a new ValueGenerationBlock with the specified number of ids.
      protected boolean repositoryExists()
      Method to return if the repository already exists.
      org.datanucleus.store.valuegenerator.ValueGenerationBlock<Long> reserveBlock​(long size)
      Method to reserve a block of "size" identities.

      • Methods inherited from class org.datanucleus.store.valuegenerator.AbstractConnectedGenerator

        getConnectionPreference, setConnectionProvider

      • Methods inherited from class org.datanucleus.store.valuegenerator.AbstractGenerator

        allocate, current, currentValue, getName, next, nextValue, obtainGenerationBlock, reserveBlock

    • Field Detail

      • connection

        protected org.datanucleus.store.connection.ManagedConnection connection
        Connection to the datastore.

      • repositoryExists

        protected boolean repositoryExists
        Flag for whether we know that the repository exists.

      • DEFAULT_TABLE_NAME

        public static final String DEFAULT_TABLE_NAME
        Default name for the datastore table storing the sequence values. Defaults to SEQUENCE_TABLE
        See Also:
        Constant Field Values

      • DEFAULT_SEQUENCE_COLUMN_NAME

        public static final String DEFAULT_SEQUENCE_COLUMN_NAME
        Default name for the column storing the name of the sequence.
        See Also:
        Constant Field Values

      • DEFAULT_NEXTVALUE_COLUMN_NAME

        public static final String DEFAULT_NEXTVALUE_COLUMN_NAME
        Default name for the column storing the next value of the sequence.
        See Also:
        Constant Field Values

    • Constructor Detail

      • TableGenerator

        public TableGenerator​(org.datanucleus.store.StoreManager storeMgr,
                      String name,
                      Properties props)
        Constructor.
        Parameters:
        storeMgr - StoreManager
        name - Symbolic name for this generator
        props - Properties defining the behaviour of this generator

    • Method Detail

      • getStorageClass

        public static Class getStorageClass()
        Accessor for the storage class for values generated with this generator.
        Returns:
        Storage class (in this case Long.class)

      • getTable

        public SequenceTable getTable()
        Convenience accessor for the table being used.
        Returns:
        The table

      • reserveBlock

        public org.datanucleus.store.valuegenerator.ValueGenerationBlock<Long> reserveBlock​(long size)
        Method to reserve a block of "size" identities.
        Specified by:
        reserveBlock in class org.datanucleus.store.valuegenerator.AbstractGenerator<Long>
        Parameters:
        size - Block size
        Returns:
        The reserved block

      • repositoryExists

        protected boolean repositoryExists()
        Method to return if the repository already exists.
        Returns:
        Whether the repository exists

      • createRepository

        protected boolean createRepository()
        Method to create the repository for ids to be stored.
        Returns:
        Whether it was created successfully.

      • initialiseSequenceTable

        protected void initialiseSequenceTable()
        Method to initialise the sequence table used for storing the sequence values.

      • obtainGenerationBlock

        protected org.datanucleus.store.valuegenerator.ValueGenerationBlock<Long> obtainGenerationBlock​(int number)
        Get a new ValueGenerationBlock with the specified number of ids.
        Overrides:
        obtainGenerationBlock in class org.datanucleus.store.valuegenerator.AbstractGenerator<Long>
        Parameters:
        number - The number of additional ids required
        Returns:
        the ValueGenerationBlock