org.datanucleus.store.rdbms.valuegenerator
Class TableGenerator

java.lang.Object
  org.datanucleus.store.valuegenerator.AbstractGenerator
      org.datanucleus.store.valuegenerator.AbstractDatastoreGenerator
          org.datanucleus.store.rdbms.valuegenerator.AbstractRDBMSGenerator
              org.datanucleus.store.rdbms.valuegenerator.TableGenerator

All Implemented Interfaces:

org.datanucleus.store.valuegenerator.ValueGenerator

public final class TableGenerator
extends AbstractRDBMSGenerator

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

Field Summary

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.

Fields inherited from class org.datanucleus.store.rdbms.valuegenerator.AbstractRDBMSGenerator

connection, LOCALISER_RDBMS

Fields inherited from class org.datanucleus.store.valuegenerator.AbstractDatastoreGenerator

connectionProvider, storeMgr

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

allocationSize, block, initialValue, LOCALISER, name, properties, repositoryExists

Constructor Summary

TableGenerator(String name, Properties props)
Constructor.

Method Summary

protected boolean	createRepository() Method to create the repository for ids to be stored.
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 boolean	repositoryExists() Method to return if the repository already exists.
protected boolean	requiresRepository() Indicator for whether the generator requires its own repository.
org.datanucleus.store.valuegenerator.ValueGenerationBlock	reserveBlock(long size) Method to reserve a block of "size" identities.

Methods inherited from class org.datanucleus.store.rdbms.valuegenerator.AbstractRDBMSGenerator

obtainGenerationBlock, requiresConnection

Methods inherited from class org.datanucleus.store.valuegenerator.AbstractDatastoreGenerator

setConnectionProvider, setStoreManager

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

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

Methods inherited from class java.lang.Object

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

Field Detail

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(String name,
                      Properties props)

Constructor.

Parameters:

name - Symbolic name for this generator

props - Properties defining the behaviour of this generator

Method Detail

getTable

public SequenceTable getTable()

Convenience accessor for the table being used.

Returns:

The table

reserveBlock

public org.datanucleus.store.valuegenerator.ValueGenerationBlock reserveBlock(long size)

Method to reserve a block of "size" identities.

Specified by:

reserveBlock in class org.datanucleus.store.valuegenerator.AbstractGenerator

Parameters:

size - Block size

Returns:

The reserved block

requiresRepository

protected boolean requiresRepository()

Indicator for whether the generator requires its own repository. This class needs a repository so returns true.

Overrides:

requiresRepository in class org.datanucleus.store.valuegenerator.AbstractGenerator

Returns:

Whether a repository is required.

repositoryExists

protected boolean repositoryExists()

Method to return if the repository already exists.

Overrides:

repositoryExists in class org.datanucleus.store.valuegenerator.AbstractGenerator

Returns:

Whether the repository exists

createRepository

protected boolean createRepository()

Method to create the repository for ids to be stored.

Overrides:

createRepository in class org.datanucleus.store.valuegenerator.AbstractGenerator

Returns:

Whether it was created successfully.

initialiseSequenceTable

protected void initialiseSequenceTable()

Method to initialise the sequence table used for storing the sequence values.