org.datanucleus.store.rdbms.valuegenerator

Class TableGenerator

java.lang.Object

org.datanucleus.store.valuegenerator.AbstractGenerator<T>

org.datanucleus.store.valuegenerator.AbstractConnectedGenerator<Long>

org.datanucleus.store.rdbms.valuegenerator.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 and 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 and Description
TableGenerator(org.datanucleus.store.StoreManager storeMgr, String name, Properties props) Constructor.

Method Summary

Modifier and Type	Method and 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

Methods inherited from class java.lang.Object

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

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