org.hibernate.id.enhanced
Class SequenceStyleGenerator

java.lang.Object
  org.hibernate.id.enhanced.SequenceStyleGenerator

All Implemented Interfaces:

Configurable, IdentifierGenerator, PersistentIdentifierGenerator

public class SequenceStyleGenerator
extends Object
implements PersistentIdentifierGenerator, Configurable

Generates identifier values based on an sequence-style database structure. Variations range from actually using a sequence to using a table to mimic a sequence. These variations are encapsulated by the DatabaseStructure interface internally.

General configuration parameters:

NAME	DEFAULT	DESCRIPTION
SEQUENCE_PARAM	DEF_SEQUENCE_NAME	The name of the sequence/table to use to store/retrieve values
INITIAL_PARAM	DEFAULT_INITIAL_VALUE	The initial value to be stored for the given segment; the effect in terms of storage varies based on Optimizer and DatabaseStructure
INCREMENT_PARAM	DEFAULT_INCREMENT_SIZE	The increment size for the underlying segment; the effect in terms of storage varies based on Optimizer and DatabaseStructure
OPT_PARAM	depends on defined increment size	Allows explicit definition of which optimization strategy to use
FORCE_TBL_PARAM	false	Allows explicit definition of which optimization strategy to use

Configuration parameters used specifically when the underlying structure is a table:

NAME	DEFAULT	DESCRIPTION
VALUE_COLUMN_PARAM	DEF_VALUE_COLUMN	The name of column which holds the sequence value for the given segment

Author:

Steve Ebersole

Field Summary

static String	DEF_SEQUENCE_NAME
static String	DEF_VALUE_COLUMN
static int	DEFAULT_INCREMENT_SIZE
static int	DEFAULT_INITIAL_VALUE
static String	FORCE_TBL_PARAM
static String	INCREMENT_PARAM
static String	INITIAL_PARAM
static String	OPT_PARAM
static String	SEQUENCE_PARAM
static String	VALUE_COLUMN_PARAM

Fields inherited from interface org.hibernate.id.PersistentIdentifierGenerator

CATALOG, IDENTIFIER_NORMALIZER, PK, SCHEMA, SQL_STATEMENT_LOGGER, TABLE, TABLES

Fields inherited from interface org.hibernate.id.IdentifierGenerator

ENTITY_NAME

Constructor Summary

SequenceStyleGenerator()

Method Summary

protected DatabaseStructure	buildDatabaseStructure(Type type, Properties params, Dialect dialect, boolean forceTableUse, String sequenceName, int initialValue, int incrementSize) Build the database structure.
void	configure(Type type, Properties params, Dialect dialect) Configure this instance, given the value of parameters specified by the user as <param> elements.
protected int	determineAdjustedIncrementSize(String optimizationStrategy, int incrementSize) In certain cases we need to adjust the increment size based on the selected optimizer.
protected int	determineIncrementSize(Properties params) Determine the increment size to be applied.
protected int	determineInitialValue(Properties params) Determine the initial sequence value to use.
protected String	determineOptimizationStrategy(Properties params, int incrementSize) Determine the optimizer to use.
protected String	determineSequenceName(Properties params, Dialect dialect) Determine the name of the sequence (or table if this resolves to a physical table) to use.
protected String	determineValueColumnName(Properties params, Dialect dialect) Determine the name of the column used to store the generator value in the db.
Serializable	generate(SessionImplementor session, Object object) Generate a new identifier.
Object	generatorKey() Return a key unique to the underlying database objects.
DatabaseStructure	getDatabaseStructure() Getter for property 'databaseStructure'.
Type	getIdentifierType() Getter for property 'identifierType'.
Optimizer	getOptimizer() Getter for property 'optimizer'.
String[]	sqlCreateStrings(Dialect dialect) The SQL required to create the underlying database objects.
String[]	sqlDropStrings(Dialect dialect) The SQL required to remove the underlying database objects.

Methods inherited from class java.lang.Object

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

Field Detail

SEQUENCE_PARAM

public static final String SEQUENCE_PARAM

See Also:

Constant Field Values

DEF_SEQUENCE_NAME

public static final String DEF_SEQUENCE_NAME

See Also:

Constant Field Values

INITIAL_PARAM

public static final String INITIAL_PARAM

See Also:

Constant Field Values

DEFAULT_INITIAL_VALUE

public static final int DEFAULT_INITIAL_VALUE

See Also:

Constant Field Values

INCREMENT_PARAM

public static final String INCREMENT_PARAM

See Also:

Constant Field Values

DEFAULT_INCREMENT_SIZE

public static final int DEFAULT_INCREMENT_SIZE

See Also:

Constant Field Values

OPT_PARAM

public static final String OPT_PARAM

See Also:

Constant Field Values

FORCE_TBL_PARAM

public static final String FORCE_TBL_PARAM

See Also:

Constant Field Values

VALUE_COLUMN_PARAM

public static final String VALUE_COLUMN_PARAM

See Also:

Constant Field Values

DEF_VALUE_COLUMN

public static final String DEF_VALUE_COLUMN

See Also:

Constant Field Values

Constructor Detail

SequenceStyleGenerator

public SequenceStyleGenerator()

Method Detail

getDatabaseStructure

public DatabaseStructure getDatabaseStructure()

Getter for property 'databaseStructure'.

Returns:

Value for property 'databaseStructure'.

getOptimizer

public Optimizer getOptimizer()

Getter for property 'optimizer'.

Returns:

Value for property 'optimizer'.

getIdentifierType

public Type getIdentifierType()

Getter for property 'identifierType'.

Returns:

Value for property 'identifierType'.

configure

public void configure(Type type,
                      Properties params,
                      Dialect dialect)
               throws MappingException

Configure this instance, given the value of parameters specified by the user as <param> elements. This method is called just once, following instantiation.

Specified by:

configure in interface Configurable

params - param values, keyed by parameter name

Throws:

MappingException

determineSequenceName

protected String determineSequenceName(Properties params,
                                       Dialect dialect)

Determine the name of the sequence (or table if this resolves to a physical table) to use.

Called during configuration.

Parameters:

params - The params supplied in the generator config (plus some standard useful extras).

dialect - The dialect in effect

Returns:

The sequence name

determineValueColumnName

protected String determineValueColumnName(Properties params,
                                          Dialect dialect)

Determine the name of the column used to store the generator value in the db.

Called during configuration when resolving to a physical table.

Parameters:

params - The params supplied in the generator config (plus some standard useful extras).

dialect - The dialect in effect.

Returns:

The value column name

determineInitialValue

protected int determineInitialValue(Properties params)

Determine the initial sequence value to use. This value is used when initializing the database structure (i.e. sequence/table).

Called during configuration.

Parameters:

params - The params supplied in the generator config (plus some standard useful extras).

Returns:

The initial value

determineIncrementSize

protected int determineIncrementSize(Properties params)

Determine the increment size to be applied. The exact implications of this value depends on the optimizer being used.

Called during configuration.

Parameters:

params - The params supplied in the generator config (plus some standard useful extras).

Returns:

The increment size

determineOptimizationStrategy

protected String determineOptimizationStrategy(Properties params,
                                               int incrementSize)

Determine the optimizer to use.

Called during configuration.

Parameters:

params - The params supplied in the generator config (plus some standard useful extras).

incrementSize - The determined increment size

Returns:

The optimizer strategy (name)

determineAdjustedIncrementSize

protected int determineAdjustedIncrementSize(String optimizationStrategy,
                                             int incrementSize)

In certain cases we need to adjust the increment size based on the selected optimizer. This is the hook to achieve that.

Parameters:

optimizationStrategy - The optimizer strategy (name)

incrementSize - The determined increment size

Returns:

The adjusted increment size.

buildDatabaseStructure

protected DatabaseStructure buildDatabaseStructure(Type type,
                                                   Properties params,
                                                   Dialect dialect,
                                                   boolean forceTableUse,
                                                   String sequenceName,
                                                   int initialValue,
                                                   int incrementSize)

Build the database structure.

Parameters:

type - The Hibernate type of the identifier property

params - The params supplied in the generator config (plus some standard useful extras).

dialect - The dialect being used.

forceTableUse - Should a table be used even if the dialect supports sequences?

sequenceName - The name to use for the sequence or table.

initialValue - The initial value.

incrementSize - the increment size to use (after any adjustments).

Returns:

An abstraction for the actual database structure in use (table vs. sequence).

generate

public Serializable generate(SessionImplementor session,
                             Object object)
                      throws HibernateException

Generate a new identifier.

Specified by:

generate in interface IdentifierGenerator

object - the entity or toplevel collection for which the id is being generated

Returns:

a new identifier

Throws:

HibernateException

generatorKey

public Object generatorKey()

Return a key unique to the underlying database objects. Prevents us from trying to create/remove them multiple times.

Specified by:

generatorKey in interface PersistentIdentifierGenerator

Returns:

Object an identifying key for this generator

sqlCreateStrings

public String[] sqlCreateStrings(Dialect dialect)
                          throws HibernateException

The SQL required to create the underlying database objects.

Specified by:

sqlCreateStrings in interface PersistentIdentifierGenerator

Parameters:

dialect - The dialect against which to generate the create command(s)

Returns:

The create command(s)

Throws:

HibernateException - problem creating the create command(s)

sqlDropStrings

public String[] sqlDropStrings(Dialect dialect)
                        throws HibernateException

The SQL required to remove the underlying database objects.

Specified by:

sqlDropStrings in interface PersistentIdentifierGenerator

Parameters:

dialect - The dialect against which to generate the drop command(s)

Returns:

The drop command(s)

Throws:

HibernateException - problem creating the drop command(s)